Article
Optics
Thomas Schuster, Felix Flicker, Ming Li, Svetlana Kotochigova, Joel E. Moore, Jun Ye, Norman Y. Yao
Summary: The paper presents a quantitative experimental blueprint for the quantum simulation of topological insulators, focusing on the Hopf insulator and introducing techniques to optimize dipolar Hopf insulators. They predict that Hopf insulators can naturally arise from dipolar interaction and demonstrate ways to control dipolar hoppings and tune resonance conditions using molecular AC polarizabilities. The experiments are capable of detecting the unconventional topology of the Hopf insulator by varying lattice termination at its edges, leading to three distinct classes of edge mode spectra.
Article
Materials Science, Multidisciplinary
Wen-Bo Dai, Hailong Li, Dong-Hui Xu, Chui-Zhen Chen, X. C. Xie
Summary: In this study, a new type of Hall effect called quantum anomalous layer Hall effect (QALHE) is observed in the even-layered two-dimensional antiferromagnetic MnBi2Te4. The quantized Hall conductance of QALHE can be controlled by a vertical electric field and can change sign with electric-field reversal in both the even-layered antiferromagnetic phase and the ferromagnetic phase. These findings offer a promising approach to electrically engineer Berry curvature monopoles and quantized-layered transport in topological magnets.
Article
Materials Science, Multidisciplinary
Lu Qi, Ai-Lei He, Hong-Fu Wang, Yongjun Liu
Summary: We demonstrate the phase transition between the trivial and the topological semimetal phases in a non-Hermitian two-leg ladder model. By studying an equivalent model with chiral symmetry, we show that the system exhibits a gapless topological semimetal phase induced by four exceptional points. Furthermore, we find that the transmission behaviors within the trivial and topological semimetal phases can be dynamically characterized by the propagation speed of the evolved initial state.
Article
Physics, Multidisciplinary
Daniel Leykam, Daria A. Smirnova
Summary: Topological invariants characterizing filled bands in electronic materials cannot be directly applied to bosonic systems. Instead, the topological invariants in bosonic systems can be determined by transitions from bound to leaky modes in photonic lattices.
Article
Optics
Pengfei Zhang
Summary: We study the quantized topological response of trapped one-dimensional quantum gases, which involves applying an optical pulse to a half-infinite region in an asymptotically harmonic trap and measuring the resulting density distribution. We prove that the corresponding linear response is described by a universal quantized formula in the thermodynamic limit, which is invariant under local continuous deformations of the trapping potential V, atom distribution fA, the spatial envelope of the optical pulse Op, and the measurement region Om. Our numerical analysis confirms this prediction with high accuracy, and we show that a short but finite optical pulse duration only causes a violation of quantization near the transition time. Our work presents an exciting avenue for exploring quantized topological phenomena in trapped quantum gases.
Article
Quantum Science & Technology
Bi-Yao Wang, Hao-Long Zhang, Shou-Bang Yang, Fan Wu, Zhen-Biao Yang, Shi-Biao Zheng
Summary: This paper proposes a scheme for measuring topological properties in a two-photon-driven Kerr-nonlinear (KNR) resonator subjected to a single-photon modulation. The topological properties are revealed through the observation of the Berry curvature and the first Chern number as a nonadiabatic response of the physical observable to the change rate of the control parameter. The parameter manifold constructed from the system's Hamiltonian indicates a topological transition when the degeneracy crosses the manifold. The scheme, utilizing continuous variable states in mesoscopic systems, offers a new perspective for exploring the geometry and topology of complex systems.
ADVANCED QUANTUM TECHNOLOGIES
(2023)
Article
Engineering, Mechanical
Yuyang Chen, Dongying Liu, Ying Wu, Peng Yu, Yijie Liu
Summary: We present a reconfigurable electro-elastic topological insulator that possesses a large Chern number, providing a new valley phase. By utilizing piezoelectric metamaterials and band structure calculations, we successfully demonstrate nontrivial topological band gaps and edge states in this system.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2023)
Article
Physics, Applied
Chol Jun Kang, Yong U. So, Un Sok Kim
Summary: The possibility of manipulating the properties of materials by using time-periodic external fields, such as circularly polarized laser fields, has led to the discovery of different topological phases. This study focuses on the bulk-edge correspondence in a honeycomb nanoribbon and observes various topological phase transitions as the intensity of the laser field increases. The results confirm the importance of the bulk-edge correspondence in periodically driven systems and highlight its potential for future material designs.
INTERNATIONAL JOURNAL OF MODERN PHYSICS B
(2023)
Article
Physics, Multidisciplinary
Man Hon Yau, C. A. R. Sa de Melo
Summary: In this study, topological insulating phases of SU(3) and SU(2) fermions in optical lattices under artificial magnetic fields were compared. It was found that SU(3) colored fermions and SU(2) spin-1/2 fermions differ in terms of topological invariants, with SU(3) fermions requiring three independent Chern numbers compared to the two required for SU(2) fermions. The results suggest the existence of three independent Chern numbers for higher fermionic irreducible representations of SU(2) and SU(3).
Article
Materials Science, Multidisciplinary
S. Wolski, M. Inglot, C. Jasiukiewicz, K. A. Kouzakov, T. Maslowski, T. Szczepanski, S. Stagraczynski, R. Stagraczynski, V. K. Dugaev, L. Chotorlishvili
Summary: The spin-dependent scattering process in a system of a topological insulator and a quantum dot is studied, and it is found that an applied external magnetic field leads to the formation of long-range entanglement in the system, which remains robust even in the presence of strong disorder.
Article
Materials Science, Multidisciplinary
Yoshihito Kuno, Yasuhiro Hatsugai
Summary: The extended Bose-Hubbard model in cold atoms in an optical lattice shows a rich phase structure with various topological phases through numerical calculations. These topological phases are connected by gapless phase boundaries, constructing various bosonic topological pumps. The center of mass under grand canonical ensemble reveals the contributions of multiple edge states and the topology of the system, demonstrating the bulk-edge correspondence of interacting bosonic pumps.
Article
Materials Science, Multidisciplinary
Bo Zhu, Shi Hu, Honghua Zhong, Yongguan Ke
Summary: We propose a scheme to measure band topology through quantized drift of Bloch oscillations in a two-dimensional Harper-Hofstadter lattice subjected to tilted fields. The quantized displacement is related to a reduced Chern number defined as a line integral of Berry curvature, providing an almost perfect measurement of Chern number. Our scheme can be applied to both energy-separable and energy-inseparable bands for detecting Chern number and topological phase transitions.
Article
Physics, Multidisciplinary
Guoyu Luo, Xinyu Lv, Lu Wen, Zhiqiang Li, Zhenbing Dai
Summary: In this study, we theoretically investigate the band structures and topological properties of AB-AB and AB-BA stacked twisted double bilayer graphene under heterostrain effect. We find that the heterostrain has different impacts on the two arrangements due to their different band gaps, and these gaps can be modified by a vertical electric field.
FRONTIERS OF PHYSICS
(2022)
Article
Physics, Multidisciplinary
Zhi-Wen Chang, Wei-Chang Hao, Xin Liu
Summary: In this paper, a gauge theory is proposed for the two-band model of Chern insulators, and the topological number in the Hall conductance is studied. By calculating the winding numbers of defects in a square lattice, the obtained evaluations for C reproduce the results of previous studies. Furthermore, a new model is proposed based on the gauge theory to obtain high Chern numbers.
COMMUNICATIONS IN THEORETICAL PHYSICS
(2022)
Article
Physics, Multidisciplinary
Ya-Li Mao, Zheng-Da Li, Sixia Yu, Jingyun Fan
Summary: This article investigates the nonlocality in a multipartite system. Theoretical and experimental studies reveal that the genuine multipartite nonlocal correlations cannot be explained by causal theories involving fewer-partite resources and global shared randomness.
PHYSICAL REVIEW LETTERS
(2022)
Article
Multidisciplinary Sciences
Tsuneya Yoshida, Tomonari Mizoguchi, Yasuhiro Hatsugai
Summary: This paper proposes a novel platform of studying non-Hermitian topology using rock-paper-scissors (RPS) cycles described by the evolutionary game theory. By analyzing the topological properties of the payoff matrix, the emergence of an exceptional point and a skin effect is demonstrated. Furthermore, striking dynamical properties in an RPS chain are discovered, including the directive propagation of population density in the bulk and the enhancement of population density around the right edge.
SCIENTIFIC REPORTS
(2022)
Article
Physics, Multidisciplinary
Tomonari Mizoguchi, Yoshihito Kuno, Yasuhiro Hatsugai
Summary: In this paper, correlation functions of one-dimensional flat-band models are calculated using the molecular-orbital representation. The calculations are simplified by utilizing the information of the molecular-orbitals instead of the explicit forms of the flat-band wave functions. Several models and their correlation functions are presented as examples. The entanglement entropy is also calculated using the correlation function.
PROGRESS OF THEORETICAL AND EXPERIMENTAL PHYSICS
(2022)
Article
Physics, Multidisciplinary
Takumi Kuroda, Tomonari Mizoguchi, Hiromu Araki, Yasuhiro Hatsugai
Summary: In this study, we investigate the characteristic probability density distribution of random flat-band models using machine learning. The models are constructed based on the molecular-orbital representation, which ensures the existence of macroscopically degenerate zero-energy modes even in the presence of randomness. We successfully distinguish flat-band states from conventional extended and localized states, indicating the unique features of flat-band states. Furthermore, we find that the flat-band states can be detected even when the target data are defined in a different lattice from the training data, suggesting the universal feature of flat-band states constructed by the molecular-orbital representation.
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN
(2022)
Article
Physics, Multidisciplinary
Daiki Matsumoto, Tomonari Mizoguchi, Yasuhiro Hatsugai
Summary: In this paper, the martini lattice model is proposed as a specific example of a higher-order topological insulator, and a square-root higher-order topological insulator based on the martini lattice model is further proposed. Through the study of the martini lattice model and the decorated honeycomb model, it is found that in-gap corner states exist at finite energies, and non-trivial bulk Z3 topological invariant protects them.
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN
(2023)
Article
Optics
Yoshihito Kuno, Yasuhiro Hatsugai
Summary: This study investigates the topological phase of a Bose gas on a two-leg ladder. The presence of a bosonic symmetry-protected-topological (SPT) phase protected by Z(2) x Z(2) symmetry is demonstrated. It is shown that the interacting bosonic system possesses various topological phases depending on the particle density and strength of interaction, using the Z(4) Berry phase.
Article
Materials Science, Multidisciplinary
Yasuhiro Hatsugai, Yoshihito Kuno
Summary: We propose a general construction scheme for a topological pump for correlated systems with local gauge symmetry. The bulk-edge correspondence is a natural consequence. As a specific example, a quantum chain associated with an SU(Q) gauge invariance of colored fermions is discussed in detail. The pump is characterized by the Q Chern numbers and the analysis under different boundary conditions clarifies the bulk-edge correspondence. The numerical demonstrations confirm the general discussions for low-energy spectra, edge states, Chern numbers, and the bulk-edge correspondence. A modified Lieb-Schultz-Mattis argument for the general SU(Q) quantum chain is also mentioned.
Article
Materials Science, Multidisciplinary
Tomonari Mizoguchi, Yanlin Gao, Mina Maruyama, Yasuhiro Hatsugai, Susumu Okada
Summary: We study characteristic electronic structures in an extended martini lattice model by investigating the minimal tight-binding model, and propose its materialization in pi-electron networks constructed by designated chemisorption on graphene and silicene. Remarkably, the unconventional gapless semiconductor with a flat band at the Fermi level can be realized by designated chemisorption or chemical substitution on graphene and silicene, and the electronic structure near the Fermi level is tunable by the choice of the atomic species of adsorbed atoms. Our results open the way to search exotic electronic structures and their functionalities induced by an extended martini lattice.
Article
Materials Science, Multidisciplinary
Tomonari Mizoguchi, Yasuhiro Hatsugai
Summary: We propose random tight-binding models that have macroscopically degenerate zero-energy modes and belong to the unitary class. By employing the molecular-orbital representation and setting the coefficients in molecular orbitals as random U(1) variables, we find two distinct behaviors compared to the random real-valued molecular-orbital model. Additionally, we also construct the random tight-binding model on a composite lattice, where we observe the realization of critical states.
Article
Materials Science, Multidisciplinary
Tsuneya Yoshida, Yasuhiro Hatsugai
Summary: In this paper, the authors investigate the effects of interactions on exceptional points in non-Hermitian systems. Their analysis in a two-dimensional parameter space reveals that exceptional points and symmetry-protected exceptional rings are no longer protected by interactions. This fragility arises from the reduction of non-Hermitian topological classifications, which is elucidated by introducing topological invariants of the second-quantized Hamiltonian for both noninteracting and interacting cases.
Article
Materials Science, Multidisciplinary
Tsuneya Yoshida, Yasuhiro Hatsugai
Summary: This study analyzes correlated non-Hermitian systems, focusing on one-dimensional point-gap topology. The research reveals that interactions reduce the topological classification of systems with charge U(1) symmetry and spin-parity symmetry, and interactions also destroy the non-Hermitian skin effect.
Article
Materials Science, Multidisciplinary
Koji Kudo, Yasuhiro Hatsugai
Summary: In this study, we numerically demonstrate the adiabatic deformation of spinful quantum Hall states by transmutation of statistical fluxes using the extended Hubbard model of anyons. The results confirm the adiabatic continuity between the singlet QH states at v = 2 and v = 2/5, consistent with the composite fermion theory with spin. The many-body Chern number of the ground-state multiplet works as an adiabatic invariant and explains the discrete change of the topological degeneracy during the evolution. The generalized Streda formula of spinful systems is justified.
Article
Materials Science, Multidisciplinary
Hiromasa Wakao, Tsuneya Yoshida, Yasuhiro Hatsugai
Summary: This paper proposes discriminant indicators for systems with generalized rotational symmetry, which can predict the occurrence of exceptional points and loops. These indicators can be computed using data from high-symmetry points, but with some limitations in terms of the number of points required. This difference from generalized inversion symmetry holds true for both two-dimensional and three-dimensional systems.
Article
Physics, Fluids & Plasmas
Shusei Makino, Takahiro Fukui, Tsuneya Yoshida, Yasuhiro Hatsugai
Summary: We propose a one-dimensional diffusion equation to study the heat conduction in systems with spatially varying diffusion constant. By diagonalizing the Hamiltonian and expanding the temperature profile using its eigenstates, we find that there exist phases with or without edge states, which affect the heat conduction behavior.
Article
Materials Science, Multidisciplinary
Tsuneya Yoshida, Ryo Okugawa, Yasuhiro Hatsugai
Summary: This paper proposes indicators for the discriminant of systems with generalized inversion symmetry, which can be computed from data at high-symmetry points in the Brillouin zone. The approach captures exceptional points and their symmetry-protected variants without ambiguity caused by the reference energy, which is an advantage compared to previously known indicators for non-Hermitian systems. As demonstrations, the authors systematically analyze 3x3 Hamiltonians where the proper choice of the reference energy is not obvious.
Article
Materials Science, Multidisciplinary
Matthew Bunney, Tomonari Mizoguchi, Yasuhiro Hatsugai, Stephan Rachel
Summary: This study investigates both first-order and second-order topology on the honeycomb lattice, realized through Haldane's model and an additional Kekule distortion, respectively. The interplay and competition of both terms result in a phase diagram containing 12 distinct phases at half-filling. All phases can be characterized by the first Chern number or a quantized ZQ Berry phase. Highlights include phases with high Chern numbers, a Z6 topological phase, and coupled kagome-lattice Chern insulators. Furthermore, insulating phases at lower fillings also exhibit first-order and second-order topological features. Real-space structures with corner states are identified at half, third, and sixth fillings, in agreement with the quantized ZQ Berry phases.
