Found 73 papers in cond-mat
Date of feed: Tue, 31 Oct 2023 00:30:00 GMT

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Comparison of grain growth mean-field models regarding predicted grain size distributions. (arXiv:2310.18317v1 [cond-mat.mtrl-sci])
Marion Roth, Baptiste Flipon, Nathalie Bozzolo, Marc Bernacki

Mean-field models have the ability to predict grain size distribution evolution occurring through thermomechanical solicitations. This article focuses on a comparison of mean-field models under grain growth conditions. Different microstructure representations are considered and discussed, especially regarding the consideration of topology in the neighborhood construction. Experimental data obtained with a heat treatment campaign on a 316L austenitic stainless steel are used for material parameters identification and as a reference for model comparisons. Mean-field models are also confronted to both mono- and bimodal initial grain size distributions to investigate the interest of introducing neighborhood topology in microstructure predictions models. This article exposes that improvements in the predictions are obtained in monomodal cases for topological models. In bimodal test, no comparison with experimental data were performed as no data were available. But relative comparisons between models indicate few differences in predictions. The interest of neighborhood topology in grain growth mean-field models gives overall small improvements compared to classical mean-field models when comparing implementation complexity.

Photonic lattices of coaxial cables: flat bands and artificial magnetic fields. (arXiv:2310.18325v1 [physics.optics])
Christopher Oliver, Denis Nabari, Hannah M. Price, Leonardo Ricci, Iacopo Carusotto

We propose the use of networks of standard, commercially-available coaxial cables as a platform to realize photonic lattice models. As a specific example, we consider a brick wall lattice formed from coaxial cables and T-shaped connectors. We calculate the dispersion of photonic Bloch waves in the lattice: we find a repeated family of three bands, which include a flat band and two Dirac points. We then demonstrate a method to displace the Dirac points, leading to an induced artificial gauge field, and a method to energetically isolate the flat band. Our results readily suggest that the interplay of nonlinearities and non-trivial topology are a natural avenue to explore in order to unlock the full power of this proposed platform.

Translation-invariant relativistic Langevin equation derived from first principles. (arXiv:2310.18327v1 [cond-mat.stat-mech])
Filippo Emanuele Zadra, Aleksandr Petrosyan, Alessio Zaccone

The relativistic Langevin equation poses a number of technical and conceptual problems related to its derivation and underlying physical assumptions. Recently, a method has been proposed in [A. Petrosyan and A. Zaccone, J. Phys. A: Math. Theor. 55 015001 (2022)] to derive the relativistic Langevin equation from a first-principles particle-bath Lagrangian. As a result of the particle-bath coupling, a new ``restoring force'' term appeared, which breaks translation symmetry. Here we revisit this problem aiming at deriving a fully translation-invariant relativistic Langevin equation. We successfully do this by adopting the renormalization potential protocol originally suggested by Caldeira and Leggett. The relativistic renormalization potential is derived here and shown to reduce to Caldeira and Leggett's form in the non-relativistic limit. The introduction of this renormalization potential successfully removes the restoring force and a fully translation-invariant relativistic Langevin equation is derived for the first time. The physically necessary character of the renormalization potential is discussed in analogy with non-relativistic systems, where it emerges due to the renormalization of the tagged particle dynamics due to its interaction with the bath oscillators (a phenomenon akin to level-repulsion or avoided-crossing in condensed matter). We discuss the properties that the corresponding non-Markovian friction kernel has to satisfy, with implications ranging from transport models of the quark-gluon plasma, to relativistic viscous hydrodynamic simulations, and to electrons in graphene.

Exciton-exciton interactions in van der Waals heterobilayers. (arXiv:2310.18328v1 [cond-mat.mes-hall])
Alexander Steinhoff, Edith Wietek, Matthias Florian, Tommy Schulz, Takashi Taniguchi, Kenji Watanabe, Shen Zhao, Alexander Högele, Frank Jahnke, Alexey Chernikov

Exciton-exciton interactions are key to understanding non-linear optical and transport phenomena in van der Waals heterobilayers, which emerged as versatile platforms to study correlated electronic states. We present a combined theory-experiment study of excitonic many-body effects based on first-principle band structures and Coulomb interaction matrix elements. Key to our approach is the explicit treatment of the fermionic substructure of excitons and dynamical screening effects for density-induced energy renormalization and dissipation. We demonstrate that dipolar blue shifts are almost perfectly compensated by many-body effects, mainly by screening-induced self-energy corrections. Moreover, we identify a crossover between attractive and repulsive behavior at elevated exciton densities. Theoretical findings are supported by experimental studies of spectrally-narrow interlayer excitons in atomically-reconstructed, hBN-encapsulated MoSe$_2$/WSe$_2$ heterobilayers. Both theory and experiment show energy renormalization on a scale of a few meV even for high injection densities in the vicinity of the Mott transition. Our results revise the established picture of dipolar repulsion dominating exciton-exciton interactions in van der Waals heterostructures and open up opportunities for their external design.

The fundamental unit of quantum conductance and quantum diffusion for a gas of massive particles. (arXiv:2310.18372v1 [cond-mat.mes-hall])
Lino Reggiani, Eleonora Alfinito, Federico Intini

By analogy with the fundamental quantum units of electrical conductance $G_0^e=\frac{2 e^2}{h}$ and thermal conductance $K_0^t=\frac{2 K_B^2 T}{h}$ we define a fundamental quantum unit of conductance, $G_0^m$, and diffusion of a massive gas of atomic particles, respectively given by $$ G_0^m=\frac{m^2}{h} \ , \ D_0=\frac{h}{m}$$ with $h$ the Planck constant, $K_B$ the Boltzmann constant, $T$ the absolute temperature, $e$ the unit charge and $m$ the mass of the atomic gas particle that move balistically in a one dimensional medium of length $L$. The effect of scattering can be accounted for by introducing an appropriate transmission probability in analogy with the quantum electrical conductance model introduced by Landauer in 1957. For an electron gas $G_0^m=1.25 \times 10^{-27} \ Kg^2/(J s)$ and $D_0 = 7.3 \times 10^{-3} \ m^2/s$, and we found a quantum expression for the generalized Einstein relation that writes $$G_0^e = \frac{2e^2m}{h^2} D_0 $$

Engineering the Kitaev spin liquid in a quantum dot system. (arXiv:2310.18393v1 [cond-mat.mes-hall])
Tessa Cookmeyer, Sankar Das Sarma

The Kitaev model on a honeycomb lattice may provide a robust topological quantum memory platform, but finding a material that realizes the unique spin liquid phase remains a considerable challenge. We demonstrate that an effective Kitaev Hamiltonian can arise from a half-filled Fermi-Hubbard Hamiltonian where each site can experience a magnetic field in a different direction. As such, we provide a method for realizing the Kitaev spin liquid on a single hexagonal plaquette made up of twelve quantum dots. Despite the small system size, there are clear signatures of the Kitaev spin-liquid ground state, and there is a range of parameters where these signatures are predicted, allowing a potential platform where Kitaev spin-liquid physics can be explored experimentally in quantum dot plaquettes.

Isotropic 3D topological phases with broken time reversal symmetry. (arXiv:2310.18400v1 [cond-mat.mes-hall])
Helene Spring, Anton R. Akhmerov, Daniel Varjas

Axial vectors, such as current or magnetization, are commonly used order parameters in time-reversal symmetry breaking systems. These vectors also break isotropy in three dimensional systems, lowering the spatial symmetry. We demonstrate that it is possible to construct a fully isotropic and inversion-symmetric three-dimensional medium where time-reversal symmetry is systematically broken. We devise a cubic crystal with scalar time-reversal symmetry breaking, implemented by hopping through chiral magnetic clusters along the crystal bonds. The presence of only the spatial symmetries of the crystal -- finite rotation and inversion symmetry -- is sufficient to protect a topological phase. The realization of this phase in amorphous systems with average continuous rotation symmetry yields a statistical topological insulator phase. We demonstrate the topological nature of our model by constructing a bulk integer topological invariant, which guarantees gapless surface spectrum on any surface with several overlapping Dirac nodes, analogous to crystalline mirror Chern insulators. We also show the expected transport properties of a three-dimensional statistical topological insulator, which remains critical on the surface for odd values of the invariant.

Machine learning detecting Majorana Zero Mode from Zero Bias Peak measurements. (arXiv:2310.18439v1 [cond-mat.mes-hall])
Mouyang Cheng, Ryotaro Okabe, Abhijatmedhi Chotrattanapituk, Mingda Li

Majorana zero modes (MZMs), emerging as exotic quasiparticles that carry non-Abelian statistics, hold great promise for achieving fault-tolerant topological quantum computation. A key signature of the presence of MZMs is the zero-bias peaks (ZBPs) from tunneling differential conductance. However, the identification of MZMs from ZBPs has faced tremendous challenges, due to the presence of topological trivial states that generate spurious ZBP signals. In this work, we introduce a machine-learning framework that can discern MZM from other signals using ZBP data. Quantum transport simulation from tight-binding models is used to generate the training data, while persistent cohomology analysis confirms the feasibility of classification via machine learning. In particular, even with added data noise, XGBoost classifier reaches $85\%$ accuracy for 1D tunneling conductance data and $94\%$ for 2D data incorporating Zeeman splitting. Tests on prior ZBP experiments show that some data are more likely to originate from MZM than others. Our model offers a quantitative approach to assess MZMs using ZBP data. Furthermore, our results shed light on the use of machine learning on exotic quantum systems with experimental-computational integration.

Weyl points on non-orientable manifolds. (arXiv:2310.18485v1 [cond-mat.mes-hall])
André Grossi e Fonseca, Sachin Vaidya, Thomas Christensen, Mikael C. Rechtsman, Taylor L. Hughes, Marin Soljačić

Weyl fermions are hypothetical chiral particles that can also manifest as excitations near three-dimensional band crossing points in lattice systems. These quasiparticles are subject to the Nielsen-Ninomiya "no-go" theorem when placed on a lattice, requiring the total chirality across the Brillouin zone to vanish. This constraint results from the topology of the (orientable) manifold on which they exist. Here, we ask to what extent the concepts of topology and chirality of Weyl points remain well-defined when the underlying manifold is non-orientable. We show that the usual notion of chirality becomes ambiguous in this setting, allowing for systems with a non-zero total chirality. Furthermore, we discover that Weyl points on non-orientable manifolds carry an additional $\mathbb{Z}_2$ topological invariant which satisfies a different no-go theorem. We implement such Weyl points by imposing a non-symmorphic symmetry in the momentum space of lattice models. Finally, we experimentally realize all aspects of their phenomenology in a photonic platform with synthetic momenta. Our work highlights the subtle but crucial interplay between the topology of quasiparticles and of their underlying manifold.

Einstein-de Haas torque as a discrete spectroscopic probe allows nanomechanical measurement of a magnetic resonance. (arXiv:2310.18546v1 [cond-mat.mes-hall])
K.R. Fast, J.E. Losby, G. Hajisalem, P.E. Barclay, M.R. Freeman

The Einstein-de Haas (EdH) effect is a fundamental, mechanical consequence of any temporal change of magnetism in an object. EdH torque results from conserving the object's total angular momentum: the angular momenta of all the specimen's magnetic moments, together with its mechanical angular momentum. Although the EdH effect is usually small and difficult to observe, it increases in magnitude with detection frequency. We explore the frequency-dependence of EdH torque for a thin film permalloy microstructure by employing a ladder of flexural beam modes (with five distinct resonance frequencies spanning from 3 to 208 MHz) within a nanocavity optomechanical torque sensor via magnetic hysteresis curves measured at mechanical resonances. At low DC fields the gyrotropic resonance of a magnetic vortex spin texture overlaps the 208 MHz mechanical mode. The massive EdH mechanical torques arising from this co-resonance yield a fingerprint of vortex core pinning and depinning in the sample. The experimental results are discussed in relation to mechanical torques predicted from both macrospin (at high DC magnetic field) and finite-difference solutions to the Landau-Lifshitz-Gilbert (LLG) equation. A global fit of the LLG solutions to the frequency-dependent data reveals a statistically significant discrepancy between the experimentally observed and simulated torque phase behaviours at spin texture transitions that can be reduced through the addition of a time constant to the conversion between magnetic cross-product torque and mechanical torque, constrained by experiment to be in the range of 0.5 - 4 ns.

Quantum Interactions in Topological R166 Kagome Magnet. (arXiv:2310.18559v1 [cond-mat.str-el])
Xitong Xu, Jia-Xin Yin, Zhe Qu, Shuang Jia

Kagome magnet has been found to be a fertile ground for the search of exotic quantum states in condensed matter. Arising from the unusual geometry, the quantum interactions in the kagome lattice give rise to various quantum states, including the Chern-gapped Dirac fermion, Weyl fermion, flat band and van Hove singularity. Here we review recent advances in the study of the R166 kagome magnet (RT6E6, R = rare earths; T = transition metals; and E = Sn, Ge, etc.) whose crystal structure highlights the transition-metal-based kagome lattice and rare-earth sublattice. Compared with other kagome magnets, the R166 family owns the particularly strong interplays between the d electrons on the kagome site and the localized f electrons on the rare-earth site. In the form of spin-orbital coupling, exchange interaction and many-body effect, the quantum interactions play an essential role in the Berry curvature field in both the reciprocal and real spaces of R166 family. We discuss the spectroscopic and transport visualization of the topological electrons hosted in the Mn kagome layer of RMn6Sn6 and the various topological effects due to the quantum interactions, including the Chern-gap opening, the exchange-biased effect, the topological Hall effect and the emergent inductance. We hope this work serves as a guide for future explorations of quantum magnets.

Varying magnetism in the lattice distorted Y2NiIrO6 and La2NiIrO6. (arXiv:2310.18641v1 [cond-mat.mtrl-sci])
Lu Liu, Ke Yang, Di Lu, Yaozhenghang Ma, Yuxuan Zhou, Hua Wu

We investigate the electronic and magnetic properties of the newly synthesized double perovskites Y$_{2}$NiIrO$_{6}$ and La$_{2}$NiIrO$_{6}$, using density functional calculations, crystal field theory, superexchange pictures, and Monte Carlo simulations. We find that both systems are antiferromagnetic (AFM) Mott insulators, with the high-spin Ni$^{2+}$ $t_{2g}$$^{6}e_{g}$$^{2}$ ($S=1$) and the low-spin Ir$^{4+}$ $t_{2g}$$^{5}$ ($S=1/2$) configurations. We address that their lattice distortion induces $t_{2g}$-$e_{g}$ orbital mixing and thus enables the normal Ni$^{+}$-Ir$^{5+}$ charge excitation with the electron hopping from the Ir `$t_{2g}$' to Ni `$e_g$' orbitals, which promotes the AFM Ni$^{2+}$-Ir$^{4+}$ coupling. Therefore, the increasing $t_{2g}$-$e_{g}$ mixing accounts for the enhanced $T_{\rm N}$ from the less distorted La$_{2}$NiIrO$_{6}$ to the more distorted Y$_{2}$NiIrO$_{6}$. Moreover, our test calculations find that in the otherwise ideally cubic Y$_{2}$NiIrO$_{6}$, the Ni$^{+}$-Ir$^{5+}$ charge excitation is forbidden, and only the abnormal Ni$^{3+}$-Ir$^{3+}$ excitation gives a weakly ferromagnetic (FM) behavior. Furthermore, we find that owing to the crystal field splitting, Hund exchange, and broad band formation in the highly coordinated fcc sublattice, Ir$^{4+}$ ions are not in the $j_{\rm eff}=1/2$ state but in the $S=1/2$ state carrying a finite orbital moment by spin-orbit coupling (SOC). This work clarifies the varying magnetism in Y$_{2}$NiIrO$_{6}$ and La$_{2}$NiIrO$_{6}$ associated with the lattice distortions.

Defect-influenced particle advection in highly confined liquid crystal flows. (arXiv:2310.18667v1 [cond-mat.soft])
Magdalena Lesniewska, Nigel Mottram, Oliver Henrich

We study the morphology of the Saturn ring defect and director structure around a colloidal particle with normal anchoring conditions and within the flow of the nematic host phase through a rectangular duct of comparable size to the particle. The changes in the defect structures and director profile influence the advection behaviour of the particle, which we compare to that in a simple Newtonian host phase. These effects lead to a non-monotonous dependence of the differential velocity of particle and fluid, also known as retardation ratio, on the Ericksen number.

Simultaneous embedding of multiple attractor manifolds in a recurrent neural network using constrained gradient optimization. (arXiv:2310.18708v1 [q-bio.NC])
Haggai Agmon, Yoram Burak

The storage of continuous variables in working memory is hypothesized to be sustained in the brain by the dynamics of recurrent neural networks (RNNs) whose steady states form continuous manifolds. In some cases, it is thought that the synaptic connectivity supports multiple attractor manifolds, each mapped to a different context or task. For example, in hippocampal area CA3, positions in distinct environments are represented by distinct sets of population activity patterns, each forming a continuum. It has been argued that the embedding of multiple continuous attractors in a single RNN inevitably causes detrimental interference: quenched noise in the synaptic connectivity disrupts the continuity of each attractor, replacing it by a discrete set of steady states that can be conceptualized as lying on local minima of an abstract energy landscape. Consequently, population activity patterns exhibit systematic drifts towards one of these discrete minima, thereby degrading the stored memory over time. Here we show that it is possible to dramatically attenuate these detrimental interference effects by adjusting the synaptic weights. Synaptic weight adjustments are derived from a loss function that quantifies the roughness of the energy landscape along each of the embedded attractor manifolds. By minimizing this loss function, the stability of states can be dramatically improved, without compromising the capacity.

Ultrafast Electron Diffuse Scattering as a Tool for Studying Phonon Transport: Phonon Hydrodynamics and Second Sound Oscillations. (arXiv:2310.18793v1 [cond-mat.mes-hall])
Laurenz Kremeyer, Tristan L. Britt, Bradley J. Siwick, Samuel C. Huberman

Hydrodynamic phonon transport phenomena, like second sound, have been observed in liquid Helium temperatures more than 50 years ago. More recently second sound has been observed in graphite at over 200\,K using transient thermal grating techniques. In this work we explore the signatures of second sound in ultrafast electron diffuse scattering (UEDS) patterns. We use density functional theory and solve the Boltzmann transport equation to determine time-resolved non-equilibrium phonon populations and subsequently calculate one-phonon structure factors and diffuse scattering patterns to simulate experimental data covering the regimes of ballistic, diffusive, and hydrodynamic phonon transport. For systems like graphite, UEDS is capable of extracting time-dependent phonon occupancies across the entire Brillouin zone and ultimately lead to a more fundamental understanding of the hydrodynamic phonon transport regime.

Donor-acceptor recombination emission in hydrogen-terminated nanodiamond: Novel single-photon source for room-temperature quantum photonics. (arXiv:2310.18822v1 [quant-ph])
D. G. Pasternak, A. M. Romshin, R. H. Bagramov, A. I. Galimov, A. A. Toropov, D. A. Kalashnikov, V. Leong, A. M. Satanin, O. S. Kudryavtsev, A. L. Chernev, V. P. Filonenko, I. I. Vlasov

In fluorescence spectra of nanodiamonds (NDs) synthesized at high pressure from adamantane and other organic compounds, very narrow (~1 nm) lines of unknown origin are observed in a wide spectroscopic range from ~500 to 800 nm. Here, we propose and experimentally substantiate the hypothesis that these mysterious lines arise from radiative recombination of donor-acceptor pairs (DAPs). To confirm our hypothesis, we study the fluorescence spectra of undoped and nitrogen-doped NDs of different sizes, before and after thermal oxidation of their surface. The results obtained with a high degree of confidence allowed us to conclude that the DAPs are formed through the interaction of donor-like substitutional nitrogen present in the diamond lattice, and a 2D layer of acceptors resulting from the transfer doping effect on the surface of hydrogen-terminated NDs. A specific behavior of the DAP-induced lines was discovered in the temperature range of 100-10 K: their energy increases and most lines are split into 2 or more components with decreasing temperature. It is shown that the majority of the studied DAP emitters are sources of single photons, with an emission rate of up to >1 million counts/s at room temperature, which significantly surpasses that of nitrogen-vacancy and silicon-vacancy centers under the same detection conditions. Despite an observed temporal instability in the emission, the DAP emitters of H-terminated NDs represent a powerful room-temperature single-photon source for quantum optical technologies.

Topological, or Non-topological? A Deep Learning Based Prediction. (arXiv:2310.18907v1 [cond-mat.mtrl-sci])
Ashiqur Rasul, Md Shafayat Hossain, Ankan Ghosh Dastider, Himaddri Roy, M. Zahid Hasan, Quazi D. M. Khosru

Prediction and discovery of new materials with desired properties are at the forefront of quantum science and technology research. A major bottleneck in this field is the computational resources and time complexity related to finding new materials from ab initio calculations. In this work, an effective and robust deep learning-based model is proposed by incorporating persistent homology and graph neural network which offers an accuracy of 91.4% and an F1 score of 88.5% in classifying topological vs. non-topological materials, outperforming the other state-of-the-art classifier models. The incorporation of the graph neural network encodes the underlying relation between the atoms into the model based on their own crystalline structures and thus proved to be an effective method to represent and process non-euclidean data like molecules with a relatively shallow network. The persistent homology pipeline in the suggested neural network is capable of integrating the atom-specific topological information into the deep learning model, increasing robustness, and gain in performance. It is believed that the presented work will be an efficacious tool for predicting the topological class and therefore enable the high-throughput search for novel materials in this field.

Band Structure of Topological Insulator BiSbTe1.25Se1.75. (arXiv:2310.18922v1 [cond-mat.mtrl-sci])
H. Lohani, P. Mishra, A. Banerjee, K. Majhi, R. Ganesan, U. Manju, D. Topwal, P. S. Anil Kumar, B. R. Sekhar

We present our angle resolved photoelectron spectroscopy (ARPES) and density functional theory results on quaternary topological insulator (TI) BiSbTe1.25Se1.75 (BSTS) confirming the non-trivial topology of the surface state bands (SSBs) in this compound. We find that the SSBs, which are are sensitive to the atomic composition of the terminating surface have a partial 3D character. Our detailed study of the band bending (BB) effects shows that in BSTS the Dirac point (DP) shifts by more than two times compared to that in Bi2Se3 to reach the saturation. The stronger BB in BSTS could be due to the difference in screening of the surface charges. From momentum density curves (MDCs) of the ARPES data we obtained an energy dispersion relation showing the warping strength of the Fermi surface in BSTS to be intermediate between those found in Bi2Se3 and Bi2Te3 and also to be tunable by controlling the ratio of chalcogen/pnictogen atoms. Our experiments also reveal that the nature of the BB effects are highly sensitive to the exposure of the fresh surface to various gas species. These findings have important implications in the tuning of DP in TIs for technological applications.

Investigation of correlation effects in FeSe and FeTe by LDA + U method. (arXiv:2310.18994v1 [cond-mat.supr-con])
H. Lohani, P. Mishra, B.R. Sekhar

Correlation effects are observed strong in Iron chalcogenides superconductors by experimental and theoretical investigations. We present a comparative study of the influence of Coulomb interaction and Hund's coupling in the electronic structure of FeSe and FeTe. The calculation is based on density functional theory (DFT) with local density approximation(LDA+U) framework employed in TB-LMTO ASA code. We found the correlation effects were orbital selective due to the strength of interorbital hybridization among different Fe-3d orbitals mediated via chalcogen (Se/Te-p) orbitals is different in both the compounds, however Coulomb interaction is screened significantly by Te-p bands in FeTe. Similarly the orbital section is different in both the compounds because of the difference in the chalcogen height.

Higher-order topological corner and bond-localized modes in magnonic insulators. (arXiv:2310.19010v1 [cond-mat.mes-hall])
Sayak Bhowmik, Saikat Banerjee, Arijit Saha

We theoretically investigate a novel two-dimensional decorated honeycomb lattice framework to realize a second-order topological magnon insulator (SOTMI) phase featuring distinct corner-localized modes. Our study emphasizes the pivotal role of spin-magnon mapping in characterizing bosonic topological properties, which exhibit differences from their fermionic counterparts. We employ a symmetry indicator topological invariant to identify and characterize this SOTMI phase, particularly for systems respecting time-reversal and ${\sf{C}}_6$ rotational symmetry. Using a spin model defined on a honeycomb lattice geometry, we demonstrate that introducing "kekule" type distortions yields a topological phase. In contrast, anti-kekule" distortions result in a non-topological magnonic phase. The presence of kekule distortions manifests in two distinct topologically protected bosonic corner modes - an "intrinsic" and a "pseudo", based on the specific edge terminations. On the other hand, anti-kekule distortions give rise to bond-localized boundary modes, which are non-topological and reliant on particular edge termination. We further investigate the effects of random out-of-plane exchange anisotropy disorder on the robustness of these bosonic corner modes. The distinction between SOTMIs and their fermionic counterparts arises due to the system-specific magnonic onsite energies, a crucial feature often overlooked in prior literature. Our study unveils exciting prospects for engineering higher-order topological phases in magnon systems and enhances our understanding of their unique behavior within decorated honeycomb lattices.

Valence band electronic structure of Pd based ternary chalcogenide superconductors. (arXiv:2310.19016v1 [cond-mat.supr-con])
H. Lohani, P. Mishra, R. Goyal, V.P.S. Awana, B.R. Sekhar

We present a comparative study of the valence band electronic structure of Pd based ternary chalcogenide superconductors Nb2Pd0.95S5, Ta2Pd0.97S6 and Ta2Pd0.97Te6 using experimental photoemission spectroscopy and density functional based theoretical calculations. We observe a qualitatively similarity between valence band (VB) spectra of Nb2Pd0.95S5 and Ta2Pd0.97S6. Further, we find a pseudogap feature in Nb2Pd0.95S5 at low temperature, unlike other two compounds. We have correlated the structural geometry with the differences in VB spectra of these compounds. The different atomic packing in these compounds could vary the strength of inter-orbital hybridization among various atoms which leads to difference in their electronic structure as clearly observed in our DOS calculations.

Stacking Group Structure of Fermionic Symmetry-Protected Topological Phases. (arXiv:2310.19058v1 [cond-mat.str-el])
Xing-Yu Ren, Shang-Qiang Ning, Yang Qi, Qing-Rui Wang, Zheng-Cheng Gu

In the past decade, there has been a systematic investigation of symmetry-protected topological (SPT) phases in interacting fermion systems. Specifically, by utilizing the concept of equivalence classes of finite-depth fermionic symmetric local unitary (FSLU) transformations and the decorating symmetry domain wall picture, a large class of fixed-point wave functions have been constructed for fermionic SPT (FSPT) phases. Remarkably, this construction coincides with the Atiyah-Hirzebruch spectral sequence, enabling a complete classification of FSPT phases. However, unlike bosonic SPT phases, the stacking group structure in fermion systems proves to be much more intricate. The construction of fixed-point wave functions does not explicitly provide this information. In this paper, we employ FSLU transformations to investigate the stacking group structure of FSPT phases. Specifically, we demonstrate how to compute stacking FSPT data from the input FSPT data in each layer, considering both unitary and anti-unitary symmetry, up to 2+1 dimensions. As concrete examples, we explictly compute the stacking group structure for crystalline FSPT phases in all 17 wallpaper groups using the fermionic crystalline equivalence principle. Importantly, our approach can be readily extended to higher dimensions, offering a versatile method for exploring the stacking group structure of FSPT phases.

Intrinsic Third Order Nonlinear Transport Responses. (arXiv:2310.19092v1 [cond-mat.mes-hall])
Debottam Mandal, Sanjay Sarkar, Kamal Das, Amit Agarwal

Nonlinear transport phenomena offer an exciting probe into the topology and band geometry of the system. Here, we investigate the intrinsic third-order nonlinear responses, independent of the scattering time, using the density matrix-based quantum kinetic formalism. We predict a new intrinsic third-order response that is dissipative and identify a novel intrinsic contribution to the dissipationless Hall response. We demonstrate that these previously unexplored contributions originate from the band geometric quantities such as the Berry curvature and symplectic connection, which are finite in systems that break time-reversal symmetry. We prescribe the symmetry dictionary for these fundamental transport coefficients and unify our quantum kinetic results with results from semiclassical wave-packet formalism. We illustrate our results in antiferromagnetic monolayer SrMnBi$_2$. Our study significantly advances the fundamental understanding of third-order responses.

Observation of Dirac-like surface state bands on the top surface of BiSe. (arXiv:2310.19150v1 [cond-mat.mtrl-sci])
H. Lohani, K. Majhi, R. Ganesan, S. Gonzalez, G. Di Santo, L. Petaccia, P. S. Anil Kumar, B. R. Sekhar

Two quintuple layers of strong topological insulator Bi2Se3 are coupled by a Bi bilayer in BiSe crystal. We investigated its electronic structure using angle resolved photoelectron spectroscopy to study its topological nature. Dirac like linearly dispersive surface state bands are observed on the 001 surface of BiSe and Sb doped BiSe, similar to Bi2Se3. Moreover, the lower part of the SSBs buries deep in the bulk valence band. Overlap region between the SSBs and BVB is large in Sb doped system and the SSBs deviate from the Dirac like linear dispersion in this region.

These results highlight the role of interlayer coupling between the Bi bilayer and the Bi2Se3 QLs.

Furthermore, we observed a large intensity imbalance in the SSBs located at the positive and negative k parallel directions. This asymmetry pattern gradually reverses as the excitation energy scans from low 14eV to high 34eV value. However, we did not observe signal of surface magnetization resulting from the intensity imbalance in SSBs due to hole-generated uncompensated spin accumulation in the photoexcitation process. The main reason for this could be the faster relaxation process for photo hole due to the presence of the Bi bilayer between the adjacent Bi2Se3 QLs. The observed photon energy dependent intensity variation could be a signature of the mixing between the spin and the orbit texture of the SSBs.

Strain control of band topology and surface states in antiferromagnetic EuCd$_2$As$_2$. (arXiv:2310.19186v1 [cond-mat.str-el])
Nayra A. Álvarez Pari, V. K. Bharadwaj, R. Jaeschke-Ubiergo, A. Valadkhani, Roser Valentí, L. Šmejkal, Jairo Sinova

Topological semimetal antiferromagnets provide a rich source of exotic topological states which can be controlled by manipulating the orientation of the N\'eel vector, or by modulating the lattice parameters through strain. We investigate via ${ab\ initio}$ density functional theory calculations, the effects of shear strain on the bulk and surface states n two antiferromagnetic EuCd$_2$As$_2$ phases with out-of-plane and in-plane spin configurations. When magnetic moments are along the $\textit{c}$-axis, a $3\%$ longitudinal or diagonal shear strain can tune the Dirac semimetal phase to an axion insulator phase, characterized by the parity-based invariant $\eta_{4I} = 2$. For an in-plane magnetic order, the axion insulator phase remains robust under all shear strains. We further find that for both magnetic orders, the bulk gap increases and a surface gap opens on the (001) surface up to 16 meV. Because of a nonzero $\eta_{4I}$ index and gapped states on the (001) surface, hinge modes are expected to happen on the side surface states between those gapped surface states. This result can provide a valuable insight in the realization of the long-sought axion states.

Trions in monolayer transition metal dichalcogenides within the hyperspherical harmonics method. (arXiv:2310.19196v1 [cond-mat.mes-hall])
Roman Ya. Kezerashvili, Shalva M.Tsiklauri, Andrew Dublin

We develop the theoretical formalism and study the formation of valley trions in transition metal dichalcogenide (TMDC) monolayers within the framework of a non-relativistic potential model using the method of hyperspherical harmonics (HH) in four-dimensional space. We present the solution of the three-body Schr\"{o}dinger equation with the Rytova-Keldysh (RK) potential by expanding the wave function of a trion in terms of the HH. The antisymmetrization of trions wave function is based on the electron and hole spin and valley indices.

We consider a long-range approximation when the RK potential is approximated by the Coulomb potential and a short-range limit when this potential is approximated by the logarithmic potential. In a diagonal approximation, the coupled system of differential equations for the hyperradial functions is decoupled in both limits. Our approach yields the analytical solution for binding energy and wave function of trions in the diagonal approximation for these two limiting cases - the Coulomb and logarithmic potentials. We obtain exact analytical expressions for eigenvalues and eigenfunctions for negatively and positively charged trions. The corresponding energy eigenvalues can be considered as the lower and upper limits for the trions binding energies.

The proposed theoretical approach can describe trions in TMDCs and address the energy difference between the binding energies of $X^{-}$ and $X^{+}$ in TMDC. Results of numerical calculations for the ground state energies with the RK potential are in good agreement with similar calculations and in reasonable agreement with experimental measurements of trion binding energies.

Tunable Atomically Wide Electrostatic Barriers Embedded in a Graphene WSe2 Heterostructure. (arXiv:2310.19238v1 [cond-mat.mes-hall])
Hui-Ying Ren, Yue Mao, Ya-Ning Ren, Qing-Feng Sun, Lin He

Inducing and controlling electrostatic barriers in two-dimensional (2D) quantum materials has shown extraordinary promise to enable control of charge carriers, and is key for the realization of nanoscale electronic and optoelectronic devices1-10. Because of their atomically thin nature, the 2D materials have a congenital advantage to construct the thinnest possible p-n junctions1,3,7,9,10. To realize the ultimate functional unit for future nanoscale devices, creating atomically wide electrostatic barriers embedded in 2D materials is desired and remains an extremely challenge. Here we report the creation and manipulation of atomically wide electrostatic barriers embedded in graphene WSe2 heterostructures. By using a STM tip, we demonstrate the ability to generate a one-dimensional (1D) atomically wide boundary between 1T-WSe2 domains and continuously tune positions of the boundary because of ferroelasticity of the 1T-WSe2. Our experiment indicates that the 1D boundary introduces atomically wide electrostatic barriers in graphene above it. Then the 1D electrostatic barrier changes a single graphene WSe2 heterostructure quantum dot from a relativistic artificial atom to a relativistic artificial molecule.

Anomalous boundary correspondence of topological phases. (arXiv:2310.19266v1 [cond-mat.str-el])
Jian-Hao Zhang, Shang-Qiang Ning

Topological phases protected by crystalline symmetries and internal symmetries are shown to enjoy fascinating one-to-one correspondence in classification. Here we investigate the physics content behind the abstract correspondence in three or higher-dimensional systems. We show correspondence between anomalous boundary states, which provides a new way to explore the quantum anomaly of symmetry from its crystalline equivalent counterpart. We show such correspondence directly in two scenarios, including the anomalous symmetry-enriched topological orders (SET) and critical surface states. (1) First of all, for the surface SET correspondence, we demonstrate it by considering examples involving time-reversal symmetry and mirror symmetry. We show that one 2D topological order can carry the time reversal anomaly as long as it can carry the mirror anomaly and vice versa, by directly establishing the mapping of the time reversal anomaly indicators and mirror anomaly indicators. Besides, we also consider other cases involving continuous symmetry, which leads us to introduce some new anomaly indicators for symmetry from its counterpart. (2) Furthermore, we also build up direct correspondence for (near) critical boundaries. Again taking topological phases protected by time reversal and mirror symmetry as examples, the direct correspondence of their (near) critical boundaries can be built up by coupled chain construction that was first proposed by Senthil and Fisher. The examples of critical boundary correspondence we consider in this paper can be understood in a unified framework that is related to \textit{hierarchy structure} of topological $O(n)$ nonlinear sigma model, that generalizes the Haldane's derivation of $O(3)$ sigma model from spin one-half system.

A Planning-and-Exploring Approach to Extreme-Mechanics Force Fields. (arXiv:2310.19306v1 [cond-mat.mtrl-sci])
Pengjie Shi, Zhiping Xu

Extreme mechanical processes such as strong lattice distortion and bond breakage during fracture are ubiquitous in nature and engineering, which often lead to catastrophic failure of structures. However, understanding the nucleation and growth of cracks is challenged by their multiscale characteristics spanning from atomic-level structures at the crack tip to the structural features where the load is applied. Molecular simulations offer an important tool to resolve the progressive microstructural changes at crack fronts and are widely used to explore processes therein, such as mechanical energy dissipation, crack path selection, and dynamic instabilities (e.g., kinking, branching). Empirical force fields developed based on local descriptors based on atomic positions and the bond orders do not yield satisfying predictions of fracture, even for the nonlinear, anisotropic stress-strain relations and the energy densities of edges. High-fidelity force fields thus should include the tensorial nature of strain and the energetics of rare events during fracture, which, unfortunately, have not been taken into account in both the state-of-the-art empirical and machine-learning force fields. Based on data generated by first-principles calculations, we develop a neural network-based force field for fracture, NN-F$^3$, by combining pre-sampling of the space of strain states and active-learning techniques to explore the transition states at critical bonding distances. The capability of NN-F$^3$ is demonstrated by studying the rupture of h-BN and twisted bilayer graphene as model problems. The simulation results confirm recent experimental findings and highlight the necessity to include the knowledge of electronic structures from first-principles calculations in predicting extreme mechanical processes.

Work statistics and generalized Loschmidt echo for the Hatano-Nelson model. (arXiv:2310.19310v1 [cond-mat.stat-mech])
Balázs Dóra, Cătălin Paşcu Moca

We focus on the biorthogonal work statistics of the interacting many-body Hatano-Nelson model after switching on the imaginary vector potential. We introduce a generalized Loschmidt echo $G(t)$ utilizing the biorthogonal metric operator. It is well suited for numerical analysis and its Fourier transform yields the probability distribution of work done. The statistics of work displays several universal features, including an exponential decay with the square of both the system size and imaginary vector potential for the probability to stay in the ground state. Additionally, its high energy tail follows a universal power law with exponent $-3$. This originates from the peculiar temporal power law decay of $G(t)$ with a time dependent exponent. The mean and the variance of work scale linearly and logarithmically with system size while all higher cumulants are non-extensive. Our results are relevant for non-unitary field theories as well.

Interlayer Conductance in the Armchair Nanotube -- Zigzag Graphene Ribbon Parallel Contact: Theoretical Proposal of Detection of Wavefunction Growing from the Edge to the Center in the Graphene Ribbon. (arXiv:2310.19361v1 [cond-mat.mes-hall])
Ryo Tamura

Sublattices A and B are opposite in the decay direction of the edge state of the zigzag graphene ribbon (ZGR). Detecting exponential growth from the zigzag edges to the ZGR center remains challenging. The tight-binding model calculations in this letter reveal that interlayer conductance manifests this growth in parallel contact with the armchair nanotube. The transfer integrals of oblique interlayer bonds are comparable to those of vertical interlayer bonds. However, the phase of the ZGR wave function strongly suppresses the contribution of oblique bonds, allowing the selective detection of the growing component.

Observation of the sliding phason mode of the incommensurate magnetic texture in Fe/Ir(111). (arXiv:2310.19484v1 [cond-mat.mtrl-sci])
Hung-Hsiang Yang, Louise Desplat, Volodymyr P. Kravchuk, Marie Hervé, Timofey Balashov, Simon Gerber, Markus Garst, Bertrand Dupé, Wulf Wulfhekel

The nanoscopic magnetic texture forming in a monolayer of iron on the (111) surface of iridium, Fe/Ir(111), is spatially modulated and uniaxially incommensurate with respect to the crystallographic periodicities. As a consequence, a low-energy magnetic excitation is expected that corresponds to the sliding of the texture along the incommensurate direction, i.e., a phason mode, which we explicitly confirm with atomistic spin simulations. Using scanning tunneling microscopy (STM), we succeed to observe this phason mode experimentally. It can be excited by the STM tip, which leads to a random telegraph noise in the tunneling current that we attribute to the presence of two minima in the phason potential due to the presence of disorder in our sample. This provides the prospect of a floating phase in cleaner samples and, potentially, a commensurate-incommensurate transition as a function of external control parameters.

Anomalous tensile strength and thermal expansion, and low thermal conductivity in wide band gap boron monoxide monolayer. (arXiv:2310.19485v1 [cond-mat.mes-hall])
Bohayra Mortazavi, Fazel Shojaei, Fei Ding, Xiaoying Zhuang

Most recently the formation of boron monoxide (BO) in the two-dimensional (2D) form has been confirmed experimentally (J. Am. Chem. Soc. 2023, 145, 14660). Motivated by the aforementioned finding, herein we theoretically explore the key physical properties of the single-layer and suspended BO. Density functional theory (DFT) results reveal that BO monolayer yields a large indirect band gap of 3.78 (2.18) eV on the basis of HSE06(PBE) functional. Ab-initio molecular dynamics results reveal the remarkable thermal stability of the BO monolayer at 1000 K. The thermal and mechanical properties at room temperature are furthermore investigated using a machine learning interatomic potential (MLIP). The developed MLIP-based model close to the ground state could very precisely reproduce the DFT predictions for the mechanical properties of the BO monolayer. The elastic modulus, tensile strength and lattice thermal conductivity of the BO monolayer at room temperature are predicted to be 107 GPa, 25 GPa and 5.6 W/mK, respectively. At the room temperature the BO monolayer is noticeably predicted to yield an ultrahigh negative thermal expansion coefficient, by almost 17 folds larger than that of the single-layer graphene. The presented results reveal the large indirect electronic band gap, decent thermal and dynamical stability, anomalously low elastic modulus to tensile strength ratio, ultrahigh negative thermal expansion coefficients and low lattice thermal conductivity of the BO monolayer.

Interacting Kitaev Chain with $\mathcal{N}=1$ Supersymmetry. (arXiv:2310.19493v1 [cond-mat.str-el])
Urei Miura, Kenji Shimomura, Keisuke Totsuka

Lattice models with supersymmetry are known to exhibit a variety of remarkable properties that do not exist in the relativistic models. In this paper, we introduce an interacting generalization of the Kitaev chain of Majorana fermions with $\mathcal{N} = 1$ supersymmetry and investigate its low-energy properties, paying particular attention to the ground-state degeneracy and low-lying fermionic excitations. First, we establish the existence of a phase with spontaneously broken supersymmetry and a phase transition out of it with the help of variational arguments and the exact ground state. We then develop, based on the superfield formalism, a simple mean-field theory, in which the order parameters detect supersymmetry-breaking, to understand the ground-state phases and low-lying Nambu-Goldstone fermions. At the solvable point ({\em frustration-free point}), the exact ground state of an open chain exhibits large degeneracy of the order of the system size, which is attributed to the existence of a zero-energy domain wall (dubbed kink or skink) separating the topological and trivial states of Majorana fermions. Our results may shed new light on the intriguing ground-state properties of supersymmetric lattice models.

Coarse-grained crystal graph neural networks for reticular materials design. (arXiv:2310.19500v1 [cond-mat.mtrl-sci])
Vadim Korolev, Artem Mitrofanov

Reticular materials, including metal-organic frameworks and covalent organic frameworks, combine relative ease of synthesis and impressive range of applications in various fields, from gas storage to biomedicine. Diverse properties arise from the variation of building units, metal centers and organic linkers, in an almost infinite chemical space. Such a variability substantially complicates experimental design and promotes the use of computational methods. In particular, the most successful artificial intelligence algorithms for predicting properties of reticular materials are atomic-level graph neural networks with optional domain knowledge. Nonetheless, the data-driven inverse design utilizing such models suffers from incorporating irrelevant and redundant features such as full atomistic graph and network topology. In this study, we propose a new way of representing materials, aiming to overcome the limitations of existing methods; the message passing is performed on the coarse-grained crystal graph that comprises molecular building units. We assess the predictive performance and energy efficiency of neural networks built on different materials representations, including composition-based and crystal-structure-aware models, to highlight the merits of our approach. Coarse-grained crystal graph neural networks show decent accuracy at low computational costs, making them a valuable alternative to omnipresent atomic-level algorithms. Moreover, the presented models can be successfully integrated into the inverse materials design pipeline as estimators of the objective function. Overall, the coarse-grained crystal graph framework aims to challenge the prevailing atomic-centric perspective on reticular materials design.

Efficient fabrication of high-density ensembles of color centers via ion implantation on a hot diamond substrate. (arXiv:2310.19526v1 [cond-mat.mtrl-sci])
E. Nieto Hernandez, G. Andrini, A. Crnjac, M. Brajkovic, F. Picariello, E. Corte, V. Pugliese, M. Matijević, P. Aprà, V. Varzi, J. Forneris, M. Genovese, Z. Siketic, M. Jaksic, S. Ditalia Tchernij

Nitrogen-Vacancy (NV) centers in diamond are promising systems for quantum technologies, including quantum metrology and sensing. A promising strategy for the achievement of high sensitivity to external fields relies on the exploitation of large ensembles of NV centers, whose fabrication by ion implantation is upper limited by the amount of radiation damage introduced in the diamond lattice. In this works we demonstrate an approach to increase the density of NV centers upon the high-fluence implantation of MeV N2+ ions on a hot target substrate (>550 {\deg}C). Our results show that, with respect to room-temperature implantation, the high-temperature process increases the vacancy density threshold required for the irreversible conversion of diamond to a graphitic phase, thus enabling to achieve higher density ensembles. Furthermore, the formation efficiency of color centers was investigated on diamond substrates implanted at varying temperatures with MeV N2+ and Mg+ ions revealing that the formation efficiency of both NV centers and magnesium-vacancy (MgV) centers increases with the implantation temperature.

Self-assembly of the chiral donor-acceptor molecule DCzDCN on Cu(100). (arXiv:2310.19534v1 [cond-mat.mtrl-sci])
Robert Ranecki, Benedikt Baumann, Stefan Lach, Christiane Ziegler

Donor-acceptor (D-A) structured molecules are essential components in organic electronics. The respective molecular structure of these molecules and their synthesis are primarily determined by the intended area of application. Typically, D-A molecules promote charge separation and transport in organic photovoltaics (OPV) or organic field-effect transistors (OFET). D-A molecules showing a larger twist angle between D and A units are, e.g., extremely important for the development of high internal quantum efficiency in organic light-emitting diodes (OLEDs). A prototypical molecule of this D-A type is DCzDCN (5-(4,6-diphenyl-1,3,5-triazin-2-yl)benzene-1,3-dinitrile). In most cases, these molecules are only investigated regarding their electronic and structural interaction in bulk aggregates but not in ultra-thin films supported by a metallic substrate. Here, we present growth and electronic structure studies of DCzDCN on a Cu(100) surface. In a complementary approach, through the use of Scanning Tunneling Microscopy and Spectroscopy (STM and STS), we were able to view both the adsorption geometry and the local electronic states of the adsorbed molecules in direct comparison with the integral electronic structure of the DCzDCN/CU(100) interface using Ultraviolet and Inverse Photoemission Spectroscopy (UPS and IPS). The orientation of the molecules with the donor part towards the substrate results in a chiral resolution at the interface due to the molecular as well as the substrate symmetry and additional strong molecular electrostatic forces. Thus, the formation of various bulk-unlike homochiral structures and the appearance of hybrid interface states (HIS) modifies the molecular electronic properties of the DCzDCN/Cu(100) system significantly compared to that of a single DCzDCN molecule. This may be not only useful for optoelectronic applications but also in organic spintronics.

Synthetic dimensions for topological and quantum phases: Perspective. (arXiv:2310.19549v1 [quant-ph])
Javier Argüello-Luengo, Utso Bhattacharya, Alessio Celi, Ravindra W. Chhajlany, Tobias Grass, Marcin Płodzień, Debraj Rakshit, Tymoteusz Salamon, Paolo Stornati, Leticia Tarruell, Maciej Lewenstein

In this Perspective article we report on recent progress on studies of synthetic dimensions, mostly, but not only, based on the research realized around the Barcelona groups (ICFO, UAB), Donostia (DIPC), Pozna\'n (UAM), Krak\'ow (UJ), and Allahabad (HRI). The concept of synthetic dimensions works particularly well in atomic physics, quantum optics, and photonics, where the internal degrees of freedom (Zeeman sublevels of the ground state, metastable excited states, or motional states for atoms, and angular momentum states or transverse modes for photons) provide the synthetic space. We describe our attempts to design quantum simulators with synthetic dimensions, to mimic curved spaces, artificial gauge fields, lattice gauge theories, twistronics, quantum random walks, and more.

Quantum spin liquids. (arXiv:2310.19577v1 [cond-mat.str-el])
T. Lancaster

A glance at recent research on magnetism turns up a curious set of articles discussing, or claiming evidence for, a state of matter called a quantum spin liquid (QSL). These articles are notable in their invocation of exotic notions of topological physics, quantum entanglement, fractional quantum numbers, anyon statistics and gauge field theories. So what is a QSL and why do we need this complicated technical vocabulary to describe it? Our aim in this article is to introduce some of these concepts and provide a discussion of what a QSL is, where it might occur in Nature and why it is of interest. As we'll see, this is a rich subject which is still in development, and unambiguous evidence for the realisation of the QSL state in a magnetic material remains hotly debated. However, the payoff in terms of the special nature of quantum entanglement in the QSL, and its diverse spectrum of unusual excitations and topological status will (at least to some extent) justify the need to engage with some powerful, occasionally abstract, technical material.

Role of Brownian motion and N\'{e}el relaxations in Mossbauer spectra of magnetic liquids. (arXiv:2310.19599v1 [cond-mat.mtrl-sci])
A. Ya. Dzyublik, V. Yu. Spivak

The absorption cross section of M\"{o}ssbauer radiation in magnetic liquids is calculated, taking into consideration both translational and rotational Brownian motion of magnetic nanoparticles. Stochastic reversals of their magnetization are also regarded in the absence of external magnetic field. The role of Brownian motion in ferrofluids is considered in the framework of the diffusion theory, while for the magnetorheological fluids with large nanoparticles it is done in the framework of the Langevin's approach. For rotation we derived the equation analogous to Langevin's equation and gave the corresponding correlation function. In both cases the equations for rotation are solved in the approximation of small rotations during lifetime of the excited state of M\"{o}ssbauer nuclei. The influence of magnetization relaxations is studied with the aid of the Blume-Tjon model.

Strong in-plane magnetic anisotropy (Co0.15Fe0.85)5GeTe2/graphene van der Waals heterostructure spin-valve at room temperature. (arXiv:2310.19618v1 [cond-mat.mes-hall])
Roselle Ngaloy, Bing Zhao, Soheil Ershadrad, Rahul Gupta, Masoumeh Davoudiniya, Lakhan Bainsla, Lars Sjöström, Anamul M. Hoque, Alexei Kalaboukhov, Peter Svedlindh, Biplab Sanyal, Saroj P. Dash

Van der Waals (vdW) magnets are promising owing to their tunable magnetic properties with doping or alloy composition, where the strength of magnetic interactions, their symmetry, and magnetic anisotropy can be tuned according to the desired application. However, most of the vdW magnet based spintronic devices are so far limited to cryogenic temperatures with magnetic anisotropies favouring out-of-plane or canted orientation of the magnetization. Here, we report room-temperature lateral spin-valve devices with strong in-plane magnetic anisotropy of the vdW ferromagnet (Co0.15Fe0.85)5GeTe2 (CFGT) in heterostructures with graphene. Magnetization measurements reveal above room-temperature ferromagnetism in CFGT with a strong in-plane magnetic anisotropy. Density functional theory calculations show that the magnitude of the anisotropy depends on the Co concentration and is caused by the substitution of Co in the outermost Fe layer. Heterostructures consisting of CFGT nanolayers and graphene were used to experimentally realize basic building blocks for spin valve devices such as efficient spin injection and detection. The spin transport and Hanle spin precession measurements prove a strong in-plane and negative spin polarization at the interface with graphene, which is supported by the calculated spin-polarized density of states of CFGT. The in-plane magnetization of CFGT at room temperature proves its usefulness in graphene lateral spin-valve devices, thus opening further opportunities for spintronic technologies.

Isolating the Nonlinear Optical Response of a MoS$_2$ Monolayer under Extreme Screening of a Metal Substrate. (arXiv:2310.19657v1 [cond-mat.mes-hall])
Tao Yang, Stephan Sleziona, Erik Pollmann, Eckart Hasselbrink, Peter Kratzer, Marika Schleberger, R. Kramer Campen, Yujin Tong

Transition metal dichalcogenides (TMDCs) monolayers, as two-dimensional (2D) direct bandgap semiconductors, hold promise for advanced optoelectronic and photocatalytic devices. Interaction with three-dimensional (3D) metals, like Au, profoundly affects their optical properties, posing challenges in characterizing the monolayer's optical responses within the semiconductor-metal junction. In this study, using precise polarization-controlled final-state sum frequency generation (FS-SFG), we successfully isolated the optical responses of a MoS$_2$ monolayer from a MoS$_2$/Au junction. The resulting SFG spectra exhibit a linear lineshape, devoid of A or B exciton features, attributed to the strong dielectric screening and substrate induced doping. The linear lineshape illustrates the expected constant density of states (DOS) at the band edge of the 2D semiconductor, a feature often obscured by excitonic interactions in week-screening conditions such as in a free-standing monolayer. Extrapolation yields the onset of a direct quasiparticle bandgap of about $1.65\pm0.20$ eV, indicating a strong bandgap renormalization. This study not only enriches our understanding of the optical responses of a 2D semiconductor in extreme screening conditions but also provides a critical reference for advancing 2D semiconductor-based photocatalytic applications.

Double-Rashba materials for nanocrystals with bright ground-state excitons. (arXiv:2310.19678v1 [cond-mat.mtrl-sci])
Michael W. Swift, Peter C. Sercel, Alexander L. Efros, John L. Lyons, David J. Norris

While nanoscale semiconductor crystallites provide versatile fluorescent materials for light-emitting devices, such nanocrystals suffer from the "dark exciton"$\unicode{x2014}$an optically inactive electronic state into which the nanocrystal relaxes before emitting. Recently, a theoretical mechanism was discovered that can potentially defeat the dark exciton. The Rashba effect can invert the order of the lowest-lying levels, creating a bright excitonic ground state. To identify materials that exhibit this behavior, here we perform an extensive high-throughput computational search of two large open-source materials databases. Based on a detailed understanding of the Rashba mechanism, we define proxy criteria and screen over 500,000 solids, generating 173 potential "bright-exciton" materials. We then refine this list with higher-level first-principles calculations to obtain 28 candidates. To confirm the potential of these compounds, we select five and develop detailed effective-mass models to determine the nature of their lowest-energy excitonic state. We find that four of the five solids (BiTeCl, BiTeI, Ga$_2$Te$_3$, and KIO$_3$) can yield bright ground-state excitons. Our approach thus reveals promising materials for future experimental investigation of bright-exciton nanocrystals.

Lattice Realizations of Topological Defects in the critical (1+1)-d Three-State Potts Model. (arXiv:2310.19703v1 [hep-th])
Madhav Sinha, Fei Yan, Linnea Grans-Samuelsson, Ananda Roy, Hubert Saleur

Topological/perfectly-transmissive defects play a fundamental role in the analysis of the symmetries of two dimensional conformal field theories (CFTs). In the present work, spin chain regularizations for these defects are proposed and analyzed in the case of the three-state Potts CFT. In particular, lattice versions for all the primitive defects are presented, with the remaining defects obtained from the fusion of the primitive ones. The defects are obtained by introducing modified interactions around two given sites of an otherwise homogeneous spin chain with periodic boundary condition. The various primitive defects are topological on the lattice except for one, which is topological only in the scaling limit. The lattice models are analyzed using a combination of exact diagonalization and density matrix renormalization group techniques. Low-lying energy spectra for different defect Hamiltonians as well as entanglement entropy of blocks located symmetrically around the defects are computed. The latter provides a convenient way to compute the $g$-function which characterizes various defects. Finally, the eigenvalues of the line operators in the "crossed channel'' and fusion of different defect lines are also analyzed. The results are all in agreement with expectations from conformal field theory.

Quantum Oscillation Signatures of Fermi Arcs in Tunnel Magnetoconductance. (arXiv:2310.19720v1 [cond-mat.mes-hall])
Adam Yanis Chaou, Vatsal Dwivedi, Maxim Breitkrei

Fermi-arc surface states of Weyl semimetals exhibit a unique combination of localization to a surface and connectivity to the bulk Weyl fermions that can move along the localization direction. We predict anomalous quantum-oscillation signatures of Fermi arcs in the tunnel mangetoconductance across an interface between two Weyl semimetals. These oscillations stem from a momentum-space analog of Aharonov-Bohm interference of electrons moving along the interface Fermi arcs, driven by an external magnetic field normal to the interface. The Fermi arcs' connectivity to the bulk enables their characterization via transport normal to the interface, while their localization manifests in a strong field-angle anisotropy of the oscillations. This combination distinguishes these anomalous oscillations from conventional Shubnikov-de Haas oscillations and makes them identifiable even in complex oscillation spectra of real materials.

Magnetic Stability, Fermi Surface Topology, and Spin-Correlated Dielectric Response in Monolayer 1T-CrTe2. (arXiv:2310.19735v1 [cond-mat.mtrl-sci])
Ahmed Elrashidy, Jia-An Yan

We have carried out density-functional theory (DFT) calculations to study the magnetic stability of both ferromagnetic (FM) and anti-ferromagnetic (AFM) states in monolayer 1T-CrTe2. Our results show that the AFM order is lower in energy and thus is the ground state. By tuning the lattice parameters, the AFM order can transition to the FM order, in good agreement with experimental observation. We observe a commensurate SDW alongside the previously predicted CDW, and attribute the AFM order to the SDW. This results in distinct hole and electron Fermi pockets and a pronounced optical anisotropy, suggesting quasi-one-dimensional behavior in this material.

Nanoscale electronic inhomogeneities in 1T-TaS$_2$. (arXiv:2310.19751v1 [cond-mat.mes-hall])
B. Campbell, J.V. Riffle, A. de la Torre, Q. Wang, K.W. Plumb, S.M. Hollen

We report a set of scanning tunneling microscopy (STM) and spectroscopy (STS) experiments studying native defects in CVT grown 1T-TaS$_2$. Six different sample surfaces from four bulk crystals were investigated. Wide area imaging reveals a prevalence of nanometer-scale electronic inhomogeneities due to native defects, with pristine regions interspersed. These inhomogeneities appear in typical as-grown crystals and coexist with a well-formed commensurate charge density wave of 1T-TaS$_2$ at low temperatures. Electronic inhomogeneities show up both as variations in the apparent height in STM and in the local density of states in STS; the bands can shift by 60 meV and the gap varies by more than 100 meV across inhomogeneities. These inhomogeneities are present in similar concentration across large-scale areas of all samples studied, but do not influence the charge density wave formation on local or global scales. The commensurate charge density wave exhibits long-range order and remains locally intact in the presence of these inhomogeneities.

Visualizing structure of correlated ground states using collective charge modes. (arXiv:2310.19771v1 [cond-mat.mes-hall])
Michał Papaj, Guangxin Ni, Cyprian Lewandowski

The variety of correlated phenomena in moir\'e systems is incredibly rich, spanning effects such as superconductivity, a generalized form of ferromagnetism, or even charge fractionalization. This wide range of quantum phenomena is partly enabled by the large number of internal degrees of freedom in these systems, such as the valley and spin degrees of freedom, which interplay decides the precise nature of the ground state. Identifying the microscopic nature of the correlated states in the moir\'e systems is, however, challenging, as it relies on interpreting transport behavior or scanning-tunneling microscopy measurements. Here we show how the real-space structure of collective charge oscillations of the correlated orders can directly encode information about the structure of the correlated state, focusing in particular on the problem of generalized Wigner crystals in moir\'e transition metal dichalcogenides. Our analysis builds upon our earlier result [10.1126/sciadv.adg3262] that the presence of a generalized Wigner crystal modifies the plasmon spectrum of the system, giving rise to new collective modes. We focus on scanning near-field optical microscopy technique (SNOM), fundamentally a charge-sensing-based method, and introduce a regime under which SNOM can operate as a probe of the spin degree of freedom.

Charge-transfer Contact to a High-Mobility Monolayer Semiconductor. (arXiv:2310.19782v1 [cond-mat.mes-hall])
Jordan Pack, Yinjie Guo, Ziyu Liu, Bjarke S. Jessen, Luke Holtzman, Song Liu, Matthew Cothrine, Kenji Watanabe, Takashi Taniguchi, David G. Mandrus, Katayun Barmak, James Hone, Cory R. Dean

Two-dimensional (2D) semiconductors, such as the transition metal dichalcogenides, have demonstrated tremendous promise for the development of highly tunable quantum devices. Realizing this potential requires low-resistance electrical contacts that perform well at low temperatures and low densities where quantum properties are relevant. Here we present a new device architecture for 2D semiconductors that utilizes a charge-transfer layer to achieve large hole doping in the contact region, and implement this technique to measure magneto-transport properties of high-purity monolayer WSe$_2$. We measure a record-high hole mobility of 80,000 cm$^2$/Vs and access channel carrier densities as low as $1.6\times10^{11}$ cm$^{-2}$, an order of magnitude lower than previously achievable. Our ability to realize transparent contact to high-mobility devices at low density enables transport measurement of correlation-driven quantum phases including observation of a low temperature metal-insulator transition in a density and temperature regime where Wigner crystal formation is expected, and observation of the fractional quantum Hall effect under large magnetic fields. The charge transfer contact scheme paves the way for discovery and manipulation of new quantum phenomena in 2D semiconductors and their heterostructures.

Nematic excitonic insulator in transition metal dichalcogenide moir\'e heterobilayers. (arXiv:2206.12427v2 [cond-mat.str-el] UPDATED)
Ming Xie, Haining Pan, Fengcheng Wu, Sankar Das Sarma

We study the effect of inter-electron Coulomb interactions on the displacement field induced topological phase transition in transition metal dichalcogenide (TMD) moir\'e heterobilayers. We find a nematic excitonic insulator (NEI) phase that breaks the moir\'e superlattice's three-fold rotational symmetry and preempts the topological phase transition in both AA and AB stacked heterobilayers when the interlayer tunneling is weak, or when the Coulomb interaction is not strongly screened. The nematicity originates from the frustration between the nontrivial spatial structure of the interlayer tunneling, which is crucial to the existence of the topological Chern band, and the interlayer coherence induced by the Coulomb interaction that favors uniformity in layer pseudo-spin orientations. We construct a unified effective two-band model that captures the physics near the band inversion and applies to both AA and AB stacked heterobilayers. Within the two-band model, the competition between the NEI phase and the Chern insulator phase can be understood as the switching of the energetic order between the $s$-wave and the $p$-wave excitons upon increasing the interlayer tunneling.

Charge-loop current order and Z3 nematicity mediated by bond-order fluctuations in kagome metal AV3Sb5 (A=Cs,Rb,K). (arXiv:2207.08068v2 [cond-mat.str-el] UPDATED)
Rina Tazai, Youichi Yamakawa, Hiroshi Kontani

Recent experiments on geometrically frustrated kagome metal AV3Sb5 (A=K, Rb, Cs) have revealed the emergence of the charge loop current (cLC) order near the bond order (BO) phase. However, the origin of the cLC and its relation to other phases have been uncovered. Here, we discover a novel mechanism of the cLC state, by focusing on the BO phase common in kagome metals. The BO fluctuations in metals mediate the odd-parity particle-hole condensation, which drives the topological charge-current. This state is further stabilized by the finite electron-phonon coupling and the off-site Coulomb interaction. Furthermore, it is worth noting that the predicted cLC+BO phase gives rise to the Z3-nematic state in addition to the giant anomalous Hall effect. The present theory predicts the close relationship between the cLC, the BO, and the nematicity, which is significant to understand the cascade of quantum electron states in kagome metals.

Braid Protected Topological Band Structures with Unpaired Exceptional Points. (arXiv:2211.05788v2 [cond-mat.mes-hall] UPDATED)
J. Lukas K. König, Kang Yang, Jan Carl Budich, Emil J. Bergholtz

We demonstrate the existence of topologically stable unpaired exceptional points (EPs), and construct simple non-Hermitian (NH) tight-binding models exemplifying such remarkable nodal phases. While fermion doubling, i.e. the necessity of compensating the topological charge of a stable nodal point by an anti-dote, rules out a direct counterpart of our findings in the realm of Hermitian semimetals, here we derive how noncommuting braids of complex energy levels may stabilize unpaired EPs. Drawing on this insight, we reveal the occurrence of a single, unpaired EP, manifested as a non-Abelian monopole in the Brillouin zone of a minimal three-band model. This third-order degeneracy represents a sweet spot within a larger topological phase that cannot be fully gapped by any local perturbation. Instead, it may only split into simpler (second-order) degeneracies that can only gap out by pairwise annihilation after having moved around inequivalent large circles of the Brillouin zone. Our results imply the incompleteness of a topological classification based on winding numbers, due to non-Abelian representations of the braid group intertwining three or more complex energy levels, and provide insights into the topological robustness of non-Hermitian systems and their non-Abelian phase transitions.

Influence of cumulative damage on synchronization of Kuramoto oscillators on networks. (arXiv:2212.08576v2 [cond-mat.stat-mech] UPDATED)
Leidy Katherin Eraso Hernández, Alejandro P. Riascos

In this paper, we study the synchronization of identical Kuramoto phase oscillators under cumulative stochastic damage to the edges of networks. We analyze the capacity of coupled oscillators to reach a coherent state from initial random phases. The process of synchronization is a global function performed by a system that gradually changes when the damage weakens individual connections of the network. We explore diverse structures characterized by different topologies. Among these are deterministic networks as a wheel or the lattice formed by the movements of the knight on a chess board, and random networks generated with the Erd\H{o}s-R\'enyi and Barab\'asi-Albert algorithms. In addition, we study the synchronization times of 109 non-isomorphic graphs with six nodes. The synchronization times and other introduced quantities are sensitive to the impact of damage, allowing us to measure the reduction of the capacity of synchronization and classify the effect of damage in the systems under study. This approach is general and paves the way for the exploration of the effect of damage accumulation in diverse dynamical processes in complex systems.

Interplay between Topological States and Rashba States as Manifested on Surface Steps at Room Temperature. (arXiv:2301.06266v2 [cond-mat.mes-hall] UPDATED)
Wonhee Ko, Seoung-Hun Kang, Jason Lapano, Hao Chang, Jacob Teeter, Hoyeon Jeon, Matthew Brahlek, Mina Yoon, Robert G. Moore, An-Ping Li

The unique spin texture of quantum states in topological materials underpins many proposed spintronic applications. However, realizations of such great potential are stymied by perturbations, such as temperature and local fields imposed by impurities and defects, that can render a promising quantum state uncontrollable. Here, we report room-temperature observation of interaction between Rashba states and topological surface states, which manifests unique spin textures controllable by layer thickness of thin films. Specifically, we combine scanning tunneling microscopy/spectroscopy with the first-principles theoretical calculation to find the robust Rashba states coexisting with topological surface states along the surface steps with characteristic spin textures in momentum space. The Rashba edge states can be switched off by reducing the thickness of a topological insulator Bi2Se3 to bolster their interaction with the hybridized topological surface states. The study unveils a manipulating mechanism of the spin textures at room temperature, reinforcing the necessity of thin film technology in controlling quantum states.

Entanglement entropy of higher rank topological phases. (arXiv:2302.11468v2 [cond-mat.str-el] UPDATED)
Hiromi Ebisu

We study entanglement entropy of unusual $\mathbb{Z}_N$ topological stabilizer codes which admit fractional excitations with restricted mobility constraint in a manner akin to fracton topological phases. It is widely known that the sub-leading term of the entanglement entropy of a disk geometry in conventional topologically ordered phases is related to the total number of the quantum dimension of the fractional excitations. We show that, in our model, such a relation does not hold, i.e, the total number of the quantum dimension varies depending on the system size, whereas the sub-leading term of the entanglement entropy takes a constant number irrespective to the system size. We give a physical interpretation of this result in the simplest case of the model. More thorough analysis on the entanglement entropy of the model on generic lattices is also presented.

Categorical Symmetry of the Standard Model from Gravitational Anomaly. (arXiv:2302.14862v2 [hep-th] UPDATED)
Pavel Putrov, Juven Wang

In the Standard Model, some combination of the baryon $\bf B$ and lepton $\bf L$ number symmetry is free of mixed anomalies with strong and electroweak $su(3) \times su(2) \times u(1)_{\tilde Y}$ gauge forces. However, it can still suffer from a mixed gravitational anomaly, hypothetically pertinent to leptogenesis in the very early universe. This happens when the total "sterile right-handed" neutrino number $n_{\nu_R}$ is not equal to the family number $N_f$. Thus the invertible $\bf B - L$ symmetry current conservation can be violated quantum mechanically by gravitational backgrounds such as gravitational instantons. In specific, we show that a noninvertible categorical $\bf B - L$ generalized symmetry still survives in gravitational backgrounds. In general, we propose a construction of noninvertible symmetry charge operators as topological defects derived from invertible anomalous symmetries that suffer from mixed gravitational anomalies. Examples include the perturbative local and nonperturbative global anomalies classified by $\mathbb{Z}$ and $\mathbb{Z}_{16}$ respectively. For this construction, we utilize the anomaly inflow bulk-boundary correspondence, the 4d Pontryagin class and the gravitational Chern-Simons 3-form, the 3d Witten-Reshetikhin-Turaev-type topological quantum field theory corresponding to a 2d rational conformal field theory with an appropriate rational chiral central charge, and the 4d $\mathbb{Z}_4^{\rm TF}$-time-reversal symmetric topological superconductor with 3d boundary topological order.

Dipole symmetries from the topology of the phase space and the constraints on the low-energy spectrum. (arXiv:2303.04479v2 [hep-th] UPDATED)
Tomas Brauner, Naoki Yamamoto, Ryo Yokokura

We demonstrate the general existence of a local dipole conservation law in bosonic field theory. The scalar charge density arises from the symplectic form of the system, whereas the tensor current descends from its stress tensor. The algebra of spatial translations becomes centrally extended in presence of field configurations with a finite nonzero charge. Furthermore, when the symplectic form is closed but not exact, the system may, surprisingly, lack a well-defined momentum density. This leads to a theorem for the presence of additional light modes in the system whenever the short-distance physics is governed by a translationally invariant local field theory. We also illustrate this mechanism for axion electrodynamics as an example of a system with Nambu-Goldstone modes of higher-form symmetries.

Transport of bound quasiparticle states in a two-dimensional boundary superfluid. (arXiv:2303.16518v2 [cond-mat.other] UPDATED)
S. Autti, R. P. Haley, A. Jennings, G. R. Pickett, M. Poole, R. Schanen, A. A. Soldatov, V. Tsepelin, J. Vonka, V. V. Zavjalov, D. E. Zmeev

The B phase of superfluid 3He can be cooled into the pure superfluid regime, where the thermal quasiparticle density is negligible. The bulk superfluid is surrounded by a quantum well at the boundaries of the container, confining a sea of quasiparticles with energies below that of those in the bulk. We can create a non-equilibrium distribution of these states within the quantum well and observe the dynamics of their motion indirectly. Here we show that the induced quasiparticle currents flow diffusively in the two-dimensional system. Combining this with a direct measurement of energy conservation, we conclude that the bulk superfluid 3He is effectively surrounded by an independent two-dimensional superfluid, which is isolated from the bulk superfluid but which readily interacts with mechanical probes. Our work shows that this two-dimensional quantum condensate and the dynamics of the surface bound states are experimentally accessible, opening the possibility of engineering two-dimensional quantum condensates of arbitrary topology.

Domain Agnostic Fourier Neural Operators. (arXiv:2305.00478v2 [cs.LG] UPDATED)
Ning Liu, Siavash Jafarzadeh, Yue Yu

Fourier neural operators (FNOs) can learn highly nonlinear mappings between function spaces, and have recently become a popular tool for learning responses of complex physical systems. However, to achieve good accuracy and efficiency, FNOs rely on the Fast Fourier transform (FFT), which is restricted to modeling problems on rectangular domains. To lift such a restriction and permit FFT on irregular geometries as well as topology changes, we introduce domain agnostic Fourier neural operator (DAFNO), a novel neural operator architecture for learning surrogates with irregular geometries and evolving domains. The key idea is to incorporate a smoothed characteristic function in the integral layer architecture of FNOs, and leverage FFT to achieve rapid computations, in such a way that the geometric information is explicitly encoded in the architecture. In our empirical evaluation, DAFNO has achieved state-of-the-art accuracy as compared to baseline neural operator models on two benchmark datasets of material modeling and airfoil simulation. To further demonstrate the capability and generalizability of DAFNO in handling complex domains with topology changes, we consider a brittle material fracture evolution problem. With only one training crack simulation sample, DAFNO has achieved generalizability to unseen loading scenarios and substantially different crack patterns from the trained scenario. Our code and data accompanying this paper are available at

Even spheres as joint spectra of matrix models. (arXiv:2305.12026v2 [math.OA] UPDATED)
Alexander Cerjan, Terry A. Loring

The Clifford spectrum is a form of joint spectrum for noncommuting matrices. This theory has been applied in photonics, condensed matter and string theory. In applications, the Clifford spectrum can be efficiently approximated using numerical methods, but this only is possible in low dimensional example. Here we examine the higher-dimensional spheres that can arise from theoretical examples. We also describe a constuctive method to generate five real symmetric almost commuting matrices that have a $K$-theoretical obstruction to being close to commuting matrices. For this, we look to matrix models of topological electric circuits.

Exciton-Sensitized Second-Harmonic Generation in 2D Heterostructures. (arXiv:2305.17512v2 [cond-mat.mtrl-sci] UPDATED)
Wontaek Kim, Gyouil Jeong, Juseung Oh, Jihun Kim, Kenji Watanabe, Takashi Taniguchi, Sunmin Ryu

The efficient optical second-harmonic generation (SHG) of two-dimensional (2D) crystals, coupled with their atomic thickness that circumvents the phase-match problem, has garnered considerable attention. While various 2D heterostructures have shown promising applications in photodetectors, switching electronics, and photovoltaics, the modulation of nonlinear optical properties in such hetero-systems remains unexplored. In this study, we investigate exciton sensitized SHG in heterobilayers of transition metal dichalcogenides (TMDs), where photoexcitation of one donor layer enhances the SHG response of the other as an acceptor. We utilize polarization-resolved interferometry to detect the SHG intensity and phase of each individual layer, revealing the energetic match between the excitonic resonances of donors and the SHG enhancement of acceptors for four TMD combinations. Our results also uncover the dynamic nature of interlayer coupling, as evidenced by the dependence of sensitization on interlayer gap spacing and the average power of the fundamental beam. This work provides insights into how interlayer coupling of two different layers can modify nonlinear optical phenomena in 2D heterostructures.

Circular dichroism induction in WS2 by a chiral plasmonic metasurface. (arXiv:2306.03028v2 [physics.optics] UPDATED)
Fernando Lorén, Cyriaque Genet, Luis Martín-Moreno

We investigate the interaction between a monolayer of WS2 and a chiral plasmonic metasurface. WS2 possesses valley excitons that selectively couple with one-handed circularly polarised light. At the same time, the chiral plasmonic metasurface exhibits spin-momentum locking, leading to a robust polarisation response in the far field. Using a scattering formalism based on the coupled mode method, we analyse various optical properties of the WS2 monolayer. Specifically, we demonstrate the generation of circular dichroism in the transition metal dichalcogenide (TMD) by harnessing the excitation of surface plasmon polaritons (SPPs) in the metasurface. Moreover, we observe the emergence of other guided modes, opening up exciting possibilities for further exploration in TMD-based devices.

Optical pumping of electronic quantum Hall states with vortex light. (arXiv:2306.03417v2 [cond-mat.mes-hall] UPDATED)
Deric Session, Mahmoud Jalali Mehrabad, Nikil Paithankar, Tobias Grass, Christian J. Eckhardt, Bin Cao, Daniel Gustavo Suárez Forero, Kevin Li, Mohammad S. Alam, Kenji Watanabe, Takashi Taniguchi, Glenn S. Solomon, Nathan Schine, Jay Sau, Roman Sordan, Mohammad Hafezi

A fundamental requirement for quantum technologies is the ability to coherently control the interaction between electrons and photons. However, in many scenarios involving the interaction between light and matter, the exchange of linear or angular momentum between electrons and photons is not feasible, a condition known as the dipole-approximation limit. An example of a case beyond this limit that has remained experimentally elusive is when the interplay between chiral electrons and vortex light is considered, where the orbital angular momentum of light can be transferred to electrons. Here, we present a novel mechanism for such an orbital angular momentum transfer from optical vortex beams to electronic quantum Hall states. Specifically, we identify a robust contribution to the radial photocurrent, in an annular graphene sample within the quantum Hall regime, that depends on the vorticity of light. This phenomenon can be interpreted as an optical pumping scheme, where the angular momentum of photons is transferred to electrons, generating a radial current, and the current direction is determined by the vorticity of the light. Our findings offer fundamental insights into the optical probing and manipulation of quantum coherence, with wide-ranging implications for advancing quantum coherent optoelectronics.

Charge conservation in spin torque oscillators leads to a self-induced torque. (arXiv:2307.05105v2 [cond-mat.mes-hall] UPDATED)
Pieter M. Gunnink, Tim Ludwig, Rembert A. Duine

Spin torque oscillators are conventionally described by the Landau-Lifshitz-Gilbert-Slonczewski (LLGS) equation. However, at the onset of oscillations, the predictions of the conventional LLGS equation differ qualitatively from experimental results and thus appear to be incomplete. In this work we show that taking charge conservation into account leads to a previously-overlooked self-induced torque, which modifies the LLGS equation. We show that the self-induced torque originates from the pumping current that a precessing magnetization drives through a magnetic tunnel junction. To illustrate the importance of the self-induced torque, we consider an in-plane magnetized nanopillar, where it gives clear qualitative corrections to the conventional LLGS description.

Minimal alternating current injection into carbon nanotubes. (arXiv:2307.11943v4 [cond-mat.mes-hall] UPDATED)
Kota Fukuzawa, Takeo Kato, Thibaut Jonckheere, Jérôme Rech, Thierry Martin

We study theoretically the effect of electronic interactions in 1d systems on electron injection using periodic Lorentzian pulses, known as Levitons. We consider specifically a system composed of a metallic single-wall carbon nanotube, described with the Luttinger liquid formalism, a scanning tunneling microscope (STM) tip, and metallic leads. Using the out-of-equilibrium Keldysh Green function formalism, we compute the current and current noise in the system. We prove that the excess noise vanishes when each Leviton injects an integer number of electrons from the STM tip into the nanotube. This extends the concept of minimal injection with Levitons to strongly correlated, uni-dimensional non-chiral systems. We also study the time-dependent current profile, and show how it is the result of interferences between pulses non-trivially reflected at the nanotube-lead interface.

Two-dimensional electron hydrodynamics in a random array of impenetrable obstacles: Magnetoresistivity, Hall viscosity, and the Landauer dipole. (arXiv:2308.06876v2 [cond-mat.mes-hall] UPDATED)
I. V. Gornyi, D. G. Polyakov

We formulate a general framework to study the flow of the electron liquid in two dimensions past a random array of impenetrable obstacles in the presence of a magnetic field. We derive a linear-response formula for the resistivity tensor $\hat\rho$ in hydrodynamics with obstacles, which expresses $\hat\rho$ in terms of the vorticity and its harmonic conjugate, both on the boundary of obstacles. In the limit of rare obstacles, in which we calculate $\hat\rho$, the contributions of the flow-induced electric field to the dissipative resistivity from the area covered by the liquid and the area inside obstacles are shown to be equal to each other. We demonstrate that the averaged electric fields outside and inside obstacles are rotated by Hall viscosity from the direction of flow. For the diffusive boundary condition on the obstacles, this effect exactly cancels in $\hat\rho$. By contrast, for the specular boundary condition, the total electric field is rotated by Hall viscosity, which means the emergence of a Hall-viscosity-induced effective -- proportional to the obstacle density -- magnetic field. Its effect on the Hall resistivity is particularly notable in that it leads to a deviation of the Hall constant from its universal value. We show that the applied magnetic field enhances hydrodynamic lubrication, giving rise to a strong negative magnetoresistance. We combine the hydrodynamic and electrostatic perspectives by discussing the distribution of charges that create the flow-induced electric field around obstacles. We provide a connection between the tensor $\hat\rho$ and the disorder-averaged electric dipole induced by viscosity at the obstacle. This establishes a conceptual link between the resistivity in hydrodynamics with obstacles and the notion of the Landauer dipole. We show that the viscosity-induced dipole is rotated from the direction of flow by Hall viscosity.

Vortex detection in atomic Bose-Einstein condensates using neural networks trained on synthetic images. (arXiv:2308.08405v2 [cond-mat.quant-gas] UPDATED)
Myeonghyeon Kim, Junhwan Kwon, Tenzin Rabga, Yong-il Shin

Quantum vortices in atomic Bose-Einstein condensates (BECs) are topological defects characterized by quantized circulation of particles around them. In experimental studies, vortices are commonly detected by time-of-flight imaging, where their density-depleted cores are enlarged. In this work, we describe a machine learning-based method for detecting vortices in experimental BEC images, particularly focusing on turbulent condensates containing irregularly distributed vortices. Our approach employs a convolutional neural network (CNN) trained solely on synthetic simulated images, eliminating the need for manual labeling of the vortex positions as ground truth. We find that the CNN achieves accurate vortex detection in real experimental images, thereby facilitating analysis of large experimental datasets without being constrained by specific experimental conditions. This novel approach represents a significant advancement in studying quantum vortex dynamics and streamlines the analysis process in the investigation of turbulent BECs.

Anomaly Enforced Gaplessness and Symmetry Fractionalization for $Spin_G$ Symmetries. (arXiv:2308.12999v2 [hep-th] UPDATED)
T. Daniel Brennan

Symmetries and their anomalies give strong constraints on renormalization group (RG) flows of quantum field theories. Recently, the identification of a theory's global symmetries with its topological sector has provided additional constraints on RG flows to symmetry preserving gapped phases due to mathematical results in category and topological quantum field theory. In this paper, we derive constraints on RG flows from $\mathbb{Z}_2$-valued pure- and mixed-gravitational anomalies that can only be activated on non-spin manifolds. We show that such anomalies cannot be matched by a unitary, symmetry preserving gapped phase without symmetry fractionalization. In particular, we discuss examples that commonly arise in $4d$ gauge theories with fermions.

Design monolayer iodinenes based on halogen bond and tiling theory. (arXiv:2309.06184v2 [cond-mat.mtrl-sci] UPDATED)
Kejun Yu, Botao Fu, Runwu Zhang, Da-shuai Ma, Xiao-ping Li, Zhi-Ming Yu, Cheng-Cheng Liu, Yugui Yao

Xenes, two-dimensional (2D) monolayers composed of a single element, with graphene as a typical representative, have attracted widespread attention. Most of the previous Xenes, X from group-IIIA to group-VIA elements have bonding characteristics of covalent bonds. In this work, we for the first time unveil the pivotal role of a halogen bond, which is a distinctive type of bonding with interaction strength between that of a covalent bond and a van der Waals interaction, in 2D group-VIIA monolayers. Combing the ingenious non-edge-to-edge tiling theory and state-of-art ab initio method with refined local density functional M06-L, we provide a precise and effective bottom-up construction of 2D iodine monolayer sheets, iodinenes, primarily governed by halogen bonds, and successfully design a category of stable iodinenes, encompassing herringbone, Pythagorean, gyrated truncated hexagonal, i.e. diatomic-kagome, and gyrated hexagonal tiling pattern. These iodinene structures exhibit a wealth of properties, such as flat bands, nontrivial topology, and fascinating optical characteristics, offering valuable insights and guidance for future experimental investigations. Our work not only unveils the unexplored halogen bonding mechanism in 2D materials but also opens a new avenue for designing other non-covalent bonding 2D materials.

Topological dualities via tensor networks. (arXiv:2309.13118v2 [cond-mat.str-el] UPDATED)
C. Wille, J. Eisert, A. Altland

The ground state of the toric code, that of the two-dimensional class D superconductor, and the partition sum of the two-dimensional Ising model are dual to each other. This duality is remarkable inasmuch as it connects systems commonly associated to different areas of physics -- that of long range entangled topological order, (topological) band insulators, and classical statistical mechanics, respectively. Connecting fermionic and bosonic systems, the duality construction is intrinsically non-local, a complication that has been addressed in a plethora of different approaches, including dimensional reduction to one dimension, conformal field theory methods, and operator algebra. In this work, we propose a unified approach to this duality, whose main protagonist is a tensor network (TN) assuming the role of an intermediate translator. Introducing a fourth node into the net of dualities offers several advantages: the formulation is integrative in that all links of the duality are treated on an equal footing, (unlike in field theoretical approaches) it is formulated with lattice precision, a feature that becomes key in the mapping of correlation functions, and their possible numerical implementation. Finally, the passage from bosons to fermions is formulated entirely within the two-dimensional TN framework where it assumes an intuitive and technically convenient form. We illustrate the predictive potential of the formalism by exploring the fate of phase transitions, point and line defects, topological boundary modes, and other structures under the mapping between system classes. Having condensed matter readerships in mind, we introduce the construction pedagogically in a manner assuming only minimal familiarity with the concept of TNs.

Structural transformations driven by local disorder at interfaces. (arXiv:2310.11863v2 [cond-mat.mtrl-sci] UPDATED)
Yanyan Liang, Grisell Díaz Leines, Ralf Drautz, Jutta Rogal

Despite the fundamental importance of solid-solid transformations in many technologies, the microscopic mechanisms remain poorly understood. Here, we explore the atomistic mechanisms at the migrating interface during solid-solid phase transformations between the topologically closed-packed A15 and body-centred cubic phase in tungsten. The high energy barriers and slow dynamics associated with this transformation require the application of enhanced molecular sampling approaches. To this end, we performed metadynamics simulations in combination with a path collective variable derived from a machine learning classification of local structural environments, which allows the system to freely sample the complex interface structure. A disordered region of varying width forming at the migrating interface is identified as a key physical descriptor of the transformation mechanisms, facilitating the atomic shuffling and rearrangement necessary for structural transformations. Furthermore, this can directly be linked to the differences in interface mobility for distinct orientation relationships as well as the formation of interfacial ledges during the migration along low-mobility directions.

Multi-moir\'{e} trilayer graphene: lattice relaxation, electronic structure, and magic angles. (arXiv:2310.12961v2 [cond-mat.str-el] UPDATED)
Charles Yang, Julian May-Mann, Ziyan Zhu, Trithep Devakul

We systematically explore the structural and electronic properties of twisted trilayer graphene systems. In general, these systems are characterized by two twist angles, which lead to two incommensurate moir\'{e} periods. We show that lattice relaxation results in the formation of domains of periodic single-moir\'{e} structures only for twist angles close to the simplest fractions. For the majority of other twist angles, the incommensurate moir\'{e} periods lead to a quasicrystalline structure. We identify experimentally relevant magic angles at which the electronic density of states is sharply peaked and strongly correlated physics is most likely to be realized.

Layer-by-Layer Assembled Nanowire Networks Enable Graph Theoretical Design of Multifunctional Coatings. (arXiv:2310.15369v2 [] UPDATED)
Wenbing Wu, Alain Kadar, Sang Hyun Lee, Bum Chul Park, Jeffery E. Raymond, Thomas K. Tsotsis, Carlos E. S. Cesnik, Sharon C. Glotzer, Valerie Goss, Nicholas A. Kotov

Multifunctional coatings are central for information, biomedical, transportation and energy technologies. These coatings must possess hard-to-attain properties and be scalable, adaptable, and sustainable, which makes layer-by-layer assembly (LBL) of nanomaterials uniquely suitable for these technologies. What remains largely unexplored is that LBL enables computational methodologies for structural design of these composites. Utilizing silver nanowires (NWs), we develop and validate a graph theoretical (GT) description of their LBL composites. GT successfully describes the multilayer structure with nonrandom disorder and enables simultaneous rapid assessment of several properties of electrical conductivity, electromagnetic transparency, and anisotropy. GT models for property assessment can be rapidly validated due to (1) quasi-2D confinement of NWs and (2) accurate microscopy data for stochastic organization of the NW networks. We finally show that spray-assisted LBL offers direct translation of the GT-based design of composite coatings to additive, scalable manufacturing of drone wings with straightforward extensions to other technologies.

Found 8 papers in prb
Date of feed: Tue, 31 Oct 2023 04:16:51 GMT

Search terms: (topolog[a-z]+)|(graphit[a-z]+)|(rhombohedr[a-z]+)|(graphe[a-z]+)|(chalcog[a-z]+)|(landau)|(weyl)|(dirac)|(STM)|(scan[a-z]+ tunne[a-z]+ micr[a-z]+)|(scan[a-z]+ tunne[a-z]+ spectr[a-z]+)|(scan[a-z]+ prob[a-z]+ micr[a-z]+)|(MoS.+\d+|MoS\d+)|(MoSe.+\d+|MoSe\d+)|(MoTe.+\d+|MoTe\d+)|(WS.+\d+|WS\d+)|(WSe.+\d+|WSe\d+)|(WTe.+\d+|WTe\d+)|(Bi\d+Rh\d+I\d+|Bi.+\d+.+Rh.+\d+.+I.+\d+.+)|(BiTeI)|(BiTeBr)|(BiTeCl)|(ZrTe5|ZrTe.+5)|(Pt2HgSe3|Pt.+2HgSe.+3)|(jacuting[a-z]+)|(flatband)|(flat.{1}band)|(LK.{1}99)

Strain-tunable topological antiferromagnetism of two-dimensional magnets with negative Poisson ratio
Yingmei Zhu, Qirui Cui, Bo Liu, Tiejun Zhou, and Hongxin Yang
Author(s): Yingmei Zhu, Qirui Cui, Bo Liu, Tiejun Zhou, and Hongxin Yang

Two-dimensional materials with a negative Poisson ratio, which exhibit unique mechanical behavior that expands laterally when stretched, have attracted considerable attention for their practical applications in sensors, biomedicine, and other fields. Here, using the elastic solid theory and first-pr…

[Phys. Rev. B 108, 134438] Published Mon Oct 30, 2023

Tuning three-dimensional higher-order topological insulators by surface state hybridization
Hao-Jie Lin, Hai-Peng Sun, Tianyu Liu, and Peng-Lu Zhao
Author(s): Hao-Jie Lin, Hai-Peng Sun, Tianyu Liu, and Peng-Lu Zhao

Higher-order topological insulators (HOTIs) are a novel class of materials that exhibit exotic boundary states. The finite size effect induced hybridization between the boundary state HOTIs, however, remains largely unexplored. In this work, we analytically and numerically study the hybridization in…

[Phys. Rev. B 108, 165427] Published Mon Oct 30, 2023

Work function dependent photogenerated carrier dynamics of defective transition metal dichalcogenide heterostructures
Tingbo Zhang, Yehui Zhang, Xianghong Niu, Qian Chen, and Jinlan Wang
Author(s): Tingbo Zhang, Yehui Zhang, Xianghong Niu, Qian Chen, and Jinlan Wang

Vacancies are commonly introduced in the preparation of transition metal dichalcogenide (TMD) heterostructures, severely affecting photogenerated carrier dynamics. Herein, we systematically explore the carrier dynamics of TMD heterostructures (metal: Mo, W; chalcogen: S, Se, Te) with the most common…

[Phys. Rev. B 108, 165428] Published Mon Oct 30, 2023

Two-dimensional electron hydrodynamics in a random array of impenetrable obstacles: Magnetoresistivity, Hall viscosity, and the Landauer dipole
I. V. Gornyi and D. G. Polyakov
Author(s): I. V. Gornyi and D. G. Polyakov

We formulate a general framework to study the flow of the electron liquid in two dimensions past a random array of impenetrable obstacles in the presence of a magnetic field. We derive a linear-response formula for the resistivity tensor $\stackrel{̂}{ρ}$ in hydrodynamics with obstacles, which expre…

[Phys. Rev. B 108, 165429] Published Mon Oct 30, 2023

Ferroelectric phase transition in a $1T$ monolayer of ${\mathrm{MoTe}}_{2}$: A first-principles study
Li-Bin Wan, Bin Xu, Peng Chen, and Jin-Zhu Zhao
Author(s): Li-Bin Wan, Bin Xu, Peng Chen, and Jin-Zhu Zhao

A ferroelectric distorted (d) 1T (d1T)-phase characterized by out-of-plane (OOP) polarization was previously predicted in monolayer transition-metal dichalcogenides, such as ${\mathrm{MoS}}_{2}$. A phenomenological model was proposed to explain the centrosymmetric 1T (c1T)-to-d1T transition; however…

[Phys. Rev. B 108, 165430] Published Mon Oct 30, 2023

Manipulation of magnetic topological textures via perpendicular strain and polarization in van der Waals magnetoelectric heterostructures
Zhong Shen, Shuai Dong, and Xiaoyan Yao
Author(s): Zhong Shen, Shuai Dong, and Xiaoyan Yao

The multifunctional manipulation of magnetic topological textures such as skyrmions and bimerons in energy-efficient ways is of great importance for spintronic applications, but it is still a big challenge. Here, by first-principles calculations and atomistic simulations, the creation and annihilati…

[Phys. Rev. B 108, L140412] Published Mon Oct 30, 2023

Quantum Monte Carlo study of semiconductor artificial graphene nanostructures
Gökhan Öztarhan, E. Bulut Kul, Emre Okcu, and A. D. Güçlü
Author(s): Gökhan Öztarhan, E. Bulut Kul, Emre Okcu, and A. D. Güçlü

Semiconductor artificial graphene nanostructures where the Hubbard model parameter $U/t$ can be of the order of 100, provide a highly controllable platform to study strongly correlated quantum many-particle phases. We use accurate variational and diffusion Monte Carlo methods to demonstrate a transi…

[Phys. Rev. B 108, L161114] Published Mon Oct 30, 2023

Weyl excitations via helicon-phonon mixing in conducting materials
Dmitry K. Efimkin and Sergey Syzranov
Author(s): Dmitry K. Efimkin and Sergey Syzranov

Quasiparticles with Weyl dispersion can display an abundance of novel topological, thermodynamic, and transport phenomena, which is why novel Weyl materials and platforms for Weyl physics are being intensively looked for in electronic, magnetic, photonic, and acoustic systems. We demonstrate that co…

[Phys. Rev. B 108, L161411] Published Mon Oct 30, 2023

Found 2 papers in prl
Date of feed: Tue, 31 Oct 2023 04:16:49 GMT

Search terms: (topolog[a-z]+)|(graphit[a-z]+)|(rhombohedr[a-z]+)|(graphe[a-z]+)|(chalcog[a-z]+)|(landau)|(weyl)|(dirac)|(STM)|(scan[a-z]+ tunne[a-z]+ micr[a-z]+)|(scan[a-z]+ tunne[a-z]+ spectr[a-z]+)|(scan[a-z]+ prob[a-z]+ micr[a-z]+)|(MoS.+\d+|MoS\d+)|(MoSe.+\d+|MoSe\d+)|(MoTe.+\d+|MoTe\d+)|(WS.+\d+|WS\d+)|(WSe.+\d+|WSe\d+)|(WTe.+\d+|WTe\d+)|(Bi\d+Rh\d+I\d+|Bi.+\d+.+Rh.+\d+.+I.+\d+.+)|(BiTeI)|(BiTeBr)|(BiTeCl)|(ZrTe5|ZrTe.+5)|(Pt2HgSe3|Pt.+2HgSe.+3)|(jacuting[a-z]+)|(flatband)|(flat.{1}band)|(LK.{1}99)

Discovery of Charge Order in the Transition Metal Dichalcogenide ${\mathrm{Fe}}_{x}{\mathrm{NbS}}_{2}$
Shan Wu, Rourav Basak, Wenxin Li, Jong-Woo Kim, Philip J. Ryan, Donghui Lu, Makoto Hashimoto, Christie Nelson, Raul Acevedo-Esteves, Shannon C. Haley, James G. Analytis, Yu He, Alex Frano, and Robert J. Birgeneau
Author(s): Shan Wu, Rourav Basak, Wenxin Li, Jong-Woo Kim, Philip J. Ryan, Donghui Lu, Makoto Hashimoto, Christie Nelson, Raul Acevedo-Esteves, Shannon C. Haley, James G. Analytis, Yu He, Alex Frano, and Robert J. Birgeneau

The Fe intercalated transition metal dichalcogenide (TMD), ${\mathrm{Fe}}_{1/3}{\mathrm{NbS}}_{2}$, exhibits remarkable resistance switching properties and highly tunable spin ordering phases due to magnetic defects. We conduct synchrotron x-ray scattering measurements on both underintercalated ($x=…

[Phys. Rev. Lett. 131, 186701] Published Mon Oct 30, 2023

Bright and Dark Quadrupolar Excitons in the ${\mathrm{WSe}}_{2}/{\mathrm{MoSe}}_{2}/{\mathrm{WSe}}_{2}$ Heterotrilayer
Yongzhi Xie, Yuchen Gao, Fengyu Chen, Yunkun Wang, Jun Mao, Qinyun Liu, Saisai Chu, Hong Yang, Yu Ye, Qihuang Gong, Ji Feng, and Yunan Gao
Author(s): Yongzhi Xie, Yuchen Gao, Fengyu Chen, Yunkun Wang, Jun Mao, Qinyun Liu, Saisai Chu, Hong Yang, Yu Ye, Qihuang Gong, Ji Feng, and Yunan Gao

Transition metal dichalcogenide heterostructures have been extensively studied as a platform for investigating exciton physics. While heterobilayers such as ${\mathrm{WSe}}_{2}/{\mathrm{MoSe}}_{2}$ have received significant attention, there has been comparatively less research on heterotrilayers, wh…

[Phys. Rev. Lett. 131, 186901] Published Mon Oct 30, 2023

Found 1 papers in prx
Date of feed: Tue, 31 Oct 2023 04:16:49 GMT

Search terms: (topolog[a-z]+)|(graphit[a-z]+)|(rhombohedr[a-z]+)|(graphe[a-z]+)|(chalcog[a-z]+)|(landau)|(weyl)|(dirac)|(STM)|(scan[a-z]+ tunne[a-z]+ micr[a-z]+)|(scan[a-z]+ tunne[a-z]+ spectr[a-z]+)|(scan[a-z]+ prob[a-z]+ micr[a-z]+)|(MoS.+\d+|MoS\d+)|(MoSe.+\d+|MoSe\d+)|(MoTe.+\d+|MoTe\d+)|(WS.+\d+|WS\d+)|(WSe.+\d+|WSe\d+)|(WTe.+\d+|WTe\d+)|(Bi\d+Rh\d+I\d+|Bi.+\d+.+Rh.+\d+.+I.+\d+.+)|(BiTeI)|(BiTeBr)|(BiTeCl)|(ZrTe5|ZrTe.+5)|(Pt2HgSe3|Pt.+2HgSe.+3)|(jacuting[a-z]+)|(flatband)|(flat.{1}band)|(LK.{1}99)

Tackling Sampling Noise in Physical Systems for Machine Learning Applications: Fundamental Limits and Eigentasks
Fangjun Hu, Gerasimos Angelatos, Saeed A. Khan, Marti Vives, Esin Türeci, Leon Bello, Graham E. Rowlands, Guilhem J. Ribeill, and Hakan E. Türeci
Author(s): Fangjun Hu, Gerasimos Angelatos, Saeed A. Khan, Marti Vives, Esin Türeci, Leon Bello, Graham E. Rowlands, Guilhem J. Ribeill, and Hakan E. Türeci

A framework to quantify the computational capacity of arbitrary physical systems in the presence of sampling noise provides a tool for best harnessing them for machine learning.

[Phys. Rev. X 13, 041020] Published Mon Oct 30, 2023

Found 1 papers in pr_res
Date of feed: Tue, 31 Oct 2023 04:16:51 GMT

Search terms: (topolog[a-z]+)|(graphit[a-z]+)|(rhombohedr[a-z]+)|(graphe[a-z]+)|(chalcog[a-z]+)|(landau)|(weyl)|(dirac)|(STM)|(scan[a-z]+ tunne[a-z]+ micr[a-z]+)|(scan[a-z]+ tunne[a-z]+ spectr[a-z]+)|(scan[a-z]+ prob[a-z]+ micr[a-z]+)|(MoS.+\d+|MoS\d+)|(MoSe.+\d+|MoSe\d+)|(MoTe.+\d+|MoTe\d+)|(WS.+\d+|WS\d+)|(WSe.+\d+|WSe\d+)|(WTe.+\d+|WTe\d+)|(Bi\d+Rh\d+I\d+|Bi.+\d+.+Rh.+\d+.+I.+\d+.+)|(BiTeI)|(BiTeBr)|(BiTeCl)|(ZrTe5|ZrTe.+5)|(Pt2HgSe3|Pt.+2HgSe.+3)|(jacuting[a-z]+)|(flatband)|(flat.{1}band)|(LK.{1}99)

Robustness of Bell violation of graph states to qubit loss
Shahar Silberstein and Rotem Arnon-Friedman
Author(s): Shahar Silberstein and Rotem Arnon-Friedman

Graph states are special entangled states advantageous for many quantum technologies, including quantum error correction, multiparty quantum communication, and measurement-based quantum computation. Yet, their fidelity is often disrupted by various errors, most notably qubit loss. In general, given …

[Phys. Rev. Research 5, 043099] Published Mon Oct 30, 2023

Found 1 papers in nat-comm

Search terms: (topolog[a-z]+)|(graphit[a-z]+)|(rhombohedr[a-z]+)|(graphe[a-z]+)|(chalcog[a-z]+)|(landau)|(weyl)|(dirac)|(STM)|(scan[a-z]+ tunne[a-z]+ micr[a-z]+)|(scan[a-z]+ tunne[a-z]+ spectr[a-z]+)|(scan[a-z]+ prob[a-z]+ micr[a-z]+)|(MoS.+\d+|MoS\d+)|(MoSe.+\d+|MoSe\d+)|(MoTe.+\d+|MoTe\d+)|(WS.+\d+|WS\d+)|(WSe.+\d+|WSe\d+)|(WTe.+\d+|WTe\d+)|(Bi\d+Rh\d+I\d+|Bi.+\d+.+Rh.+\d+.+I.+\d+.+)|(BiTeI)|(BiTeBr)|(BiTeCl)|(ZrTe5|ZrTe.+5)|(Pt2HgSe3|Pt.+2HgSe.+3)|(jacuting[a-z]+)|(flatband)|(flat.{1}band)|(LK.{1}99)

Localization and interaction of interlayer excitons in MoSe2/WSe2 heterobilayers
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