Article
Materials Science, Multidisciplinary
K. H. M. Chen, K. Y. Lin, S. W. Lien, S. W. Huang, C. K. Cheng, H. Y. Lin, C-H Hsu, T-R Chang, C-M Cheng, M. Hong, J. Kwo
Summary: Topological material α-Sn exhibits rich topological phases and its band structure is influenced by strain and confinement effects. Researchers found that the gapped surface states of α-Sn transformed into linearly dispersive TSS at a critical thickness of 6 bilayers (BL), indicating a phase transition from trivial to nontrivial. Additional Rashba-like surface states (RSS) were identified in films thicker than 30 BL, serving as preformed TSS in another strain-induced topological phase transition. In thick films of 370 BL, α-Sn displayed a Dirac semimetal phase with Dirac nodes located along Gamma-Z. This thickness-dependent band structure study deepens the understanding of topological phase transitions and the evolution of Dirac states, and the coexistence of TSS and RSS in α-Sn may significantly enhance its potential for spintronic applications.
Article
Physics, Multidisciplinary
Zhenjiu Wang, Michael P. Zaletel, Roger S. K. Mong, Fakher F. Assaad
Summary: The study utilizes the half-filled zeroth Landau level in graphene as a regularization scheme to explore the physics of the SO(5) nonlinear sigma model subject to a Wess-Zumino-Witten topological term in 2 + 1 dimensions. The research shows an ordered phase within a specific parameter range, indicating the potential for deconfined quantum phase transitions between valence bond solids and antiferromagnets.
PHYSICAL REVIEW LETTERS
(2021)
Article
Chemistry, Physical
Yizhou Liu, Jiewen Xiao, Jahyun Koo, Binghai Yan
Summary: The study introduces the orbital polarization effect to elucidate chiral-induced spin selectivity, revealing the correlation between orbital texture and spin polarization in chiral molecules. The research also predicts the potential of inducing spin-selective phenomena in non-chiral materials.
Article
Chemistry, Physical
Xianghui Duan, Nan Sun, Luqian Fu, Baozeng Zhou, Xiaocha Wang
Summary: Two-dimensional MXenes, including Zr2CCl2, have attracted attention for their unique electronic properties and potential applications in spintronic devices. The electronic structure of Zr2CCl2 with Cl functional groups adsorbed at different symmetrical positions was systematically studied using density functional theory. The Dirac-like structure of Zr2CCl2 with a band gap shows promise in electronic applications.
APPLIED SURFACE SCIENCE
(2022)
Article
Physics, Multidisciplinary
M. Muehlhauser, K. P. Schmidt, J. Vidal, M. R. Walther
Summary: We investigate the competition between two different topological orders in three dimensions by studying the X-cube model and the three-dimensional toric code. By decomposing the corresponding Hamiltonian and calculating high-order series expansions of the ground-state energy, we determine the phase diagram and the nature of phase transitions.
Article
Physics, Applied
Mahmoud M. Asmar, Gaurav Gupta, Wang-Kong Tse
Summary: This work demonstrates the essential role of particle-hole asymmetry in describing the energy spectrum and magneto-optical response in thin-films of topological insulators (TIs). The longitudinal optical conductivity in TIs with substantial particle-hole symmetry breaking exhibits absorption peaks arising from optical transitions between bulk and surface Landau levels. The transition energies between these levels show distinct magnetic field dependence, revealing the particle-hole asymmetry in TI thin-films.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Physics, Multidisciplinary
Kai Hu, Yujie Qin, Liang Cheng, Youguo Shi, Jingbo Qi
Summary: The nonlinear optical properties of molybdenum phosphide (MoP) with three-component fermions are investigated using static and time-resolved second harmonic generation. Large second harmonic generation signals are detected in MoP, and the derived chi (2) value is higher than that of typical electro-optic materials. Unlike other topological materials, no photoinduced symmetry change is observed in MoP upon optical excitation.
CHINESE PHYSICS LETTERS
(2023)
Article
Physics, Multidisciplinary
Athanasios Chatzistavrakidis, Larisa Jonke, Thomas Strobl, Grgur Simunic
Summary: We present the construction of the classical Batalin-Vilkovisky (BV) action for topological Dirac sigma models, which are two-dimensional topological field theories that simultaneously generalize the completely gauged Wess-Zumino-Novikov-Witten model and the Poisson sigma model. The construction of the BV action for general Dirac sigma models is not applicable using the AKSZ construction, so we follow a direct approach to determine a suitable BV extension of the classical action functional. Special attention is paid to target space covariance, which requires the introduction of two connections with torsion on the Dirac structure.
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
(2023)
Article
Materials Science, Multidisciplinary
Jiacheng Gao, Zhaopeng Guo, Hongming Weng, Zhijun Wang
Summary: The study of magnetic topological materials is of great interest for realizing novel topological phases and pursuing potential applications in low-energy consumption spintronics. In this research, starting from the theory of nonmagnetic topological quantum chemistry, the researchers obtained irreducible (co)representations and compatibility relations in momentum space and constructed a complete list of magnetic band (co)representations in real space. They also developed symmetry indicators (SIs) to diagnose topological magnetic materials and identified numerous magnetic topological candidates through spin-polarized calculations.
Article
Materials Science, Multidisciplinary
Hong-Jie Pang, Hao Yu, Wei-Jian Li, Liu-Cheng Chen, Peng-Fei Qiu, Qing Peng, Xiao-Jia Chen
Summary: The effects of topological states on the thermoelectric performance of a Yb-filled CoSb3 skutterudite are studied. The nontrivial topological states are revealed by ab initio calculations and inferred from anomalous Hall conductivity and magnetoresistance. The linear bands associated with the topological states result in low effective mass and high carrier mobility, leading to high power factor. Additionally, filling the voids with Yb atoms raises the valley degeneracy, favoring the Seebeck coefficient and density-of-states effective mass. These effects contribute to the high power factor of the Yb-filled CoSb3 skutterudite. Our results highlight the crucial role of topological states in improving the performance of thermoelectric materials.
Article
Physics, Multidisciplinary
Oguzhan Can, Tarun Tummuru, Ryan P. Day, Ilya Elfimov, Andrea Damascelli, Marcel Franz
Summary: When assembled into bilayers with a twist, two monolayers of bismuth-containing cuprate can form a high-temperature topological superconductor, leading to new physical phenomena.
Article
Chemistry, Inorganic & Nuclear
Yang Zhou, Xiaomeng Liu, Zheshuai Lin, Yanqiang Li, Qingran Ding, Youchao Liu, Yangxin Chen, Sangen Zhao, Maochun Hong, Junhua Luo
Summary: This study successfully designed and synthesized two new deep-ultraviolet nonlinear optical crystals by using a bandgap-directed computer-aided material design approach. The transmittance spectrum of one of the crystals, KZnSO4F, showed a significant blue-shifted transparency window to <190 nm, which was explained by first-principles calculations. This work pushes the transparency windows of KTP-like NLO sulfates into the deep-UV spectral region for the first time and will pave a prospective way to the accurate design and synthesis of new deep-UV NLO materials.
INORGANIC CHEMISTRY
(2021)
Article
Chemistry, Multidisciplinary
Yao Li, John W. Bowers, Joseph A. Hlevyack, Meng-Kai Lin, Tai-Chang Chiang
Summary: Epitaxial thin-film heterostructures provide a platform for realizing topological surface states, and the experimental demonstration presented here confirms the formation of emergent topological states in such heterostructures. The results illustrate the rich physics of engineered composite topological systems that may be exploited for nanoscale spintronics applications.
Article
Materials Science, Multidisciplinary
A. M. Marques, R. G. Dias
Summary: The concept of 2(n)-root topology has been introduced and applied in one-dimensional and two-dimensional systems. By iteratively squaring the Hamiltonians and applying different energy downshifts, decoupled models with specific topological features can be obtained. In certain cases, a 4-root version has been found in two-dimensional models, allowing for the mapping between non-Hermitian models and their Hermitian counterparts in some scenarios.
Article
Multidisciplinary Sciences
Maia G. Vergniory, Benjamin J. Wieder, Luis Elcoro, Stuart S. P. Parkin, Claudia Felser, B. Andrei Bernevig, Nicolas Regnault
Summary: Topological quantum chemistry and symmetry-based indicators have been used to search for materials with topological properties. This study implemented a publicly accessible catalog of stable and fragile topology in all bands at and away from the Fermi energy (E-F) in the Inorganic Crystal Structure Database. The calculations revealed the symmetry-indicated band topology of known nonmagnetic materials and led to the discovery of repeat-topological and supertopological materials.
Article
Physics, Multidisciplinary
Kohei Kawabata, Shinsei Ryu
Summary: The authors developed a scaling theory of localization in non-Hermitian systems, revealing that non-Hermiticity introduces a new scale and breaks down the conventional one-parameter scaling theory of localization. The unconventional non-Hermitian delocalization is identified as originating from the two-parameter scaling. Furthermore, based on reciprocity, the authors established the threefold universality of non-Hermitian localization, where reciprocity prohibits delocalization without internal degrees of freedom, and symplectic reciprocity results in a new type of symmetry-protected delocalization.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Particles & Fields
Jonah Kudler-Flam, Yuya Kusuki, Shinsei Ryu
Summary: The study investigates the dynamics of various entanglement measures in quantum systems after exciting the ground state, revealing a close-knit structure among them that strongly depends on the chaoticity of the theory. Evidence is found for breakdown of the quasi-particle picture in 2D conformal field theories and universality of entanglement dynamics in non-equilibrium systems.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Physics, Multidisciplinary
Kohei Kawabata, Ken Shiozaki, Shinsei Ryu
Summary: This paper develops a field-theoretical description of intrinsic non-Hermitian topological phases, formulated solely in terms of spatial degrees of freedom. The theory provides a universal understanding of non-Hermitian topological phenomena and systematically predicts new physics like transport phenomena and skin effects induced by a perpendicular spatial texture in two dimensions. The non-Hermitian skin effect is shown to be a signature of an anomaly from the field-theoretical perspective.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Particles & Fields
Jonah Kudler-Flam, Vladimir Narovlansky, Shinsei Ryu
Summary: The negativity spectrum, a measure of entanglement, is investigated in both pure and mixed states. A diagrammatic method and modification of the Ford-Fulkerson algorithm are used to find the negativity spectrum in random tensor networks and holographic states. New negativity spectra are discovered in these systems, as well as in phase transitions and wormholes.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Physics, Multidisciplinary
Shinsei Ryu, Junggi Yoon
Summary: We study the two-dimensional free symplectic fermion theory with antiperiodic boundary condition and address the issue of negative norm states. By introducing a new inner product, we demonstrate that this problem can be resolved. Moreover, we establish the connection between the path integral formalism and the operator formalism in deriving this new inner product. Additionally, we investigate α vacua in which the Hamiltonian appears non-Hermitian, yet the energy spectrum is found to be real. We also compare the correlation function between the α vacua and the de Sitter space.
PHYSICAL REVIEW LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Anish Kulkarni, Tokiro Numasawa, Shinsei Ryu
Summary: In this study, the Lindbladian dynamics of the Sachdev-Ye-Kitaev (SYK) model coupled to Markovian reservoirs with different types of jump operators was investigated. Analytical results for the stationary Green's functions and decay rates of the SYK Lindbladians were obtained in the large N and large N/M limits. The distribution of eigenvalues of SYK Lindbladians for finite N was also analyzed.
Article
Astronomy & Astrophysics
Ki-Seok Kim, Shinsei Ryu, Kanghoon Lee
Summary: In holographic duality, a theory framework that describes the renormalization group flow of a quantum field theory by introducing additional dimensions, we develop a new holographic description that encodes the information of the renormalization group flow and the quantum field theory into an effective field theory. We demonstrate the self-consistency of this dual construction under the assumption of bulk locality.
Article
Materials Science, Multidisciplinary
Yuhan Liu, Ramanjit Sohal, Jonah Kudler-Flam, Shinsei Ryu
Summary: We study multipartitions of the gapped ground states of (2+1)-dimensional topological liquids and compute various correlation measures. By introducing vertex states in (1+1)-dimensional conformal field theory, we can explicitly construct the reduced density matrix. The results provide important insights and applications for understanding and utilizing topological liquids.
Article
Materials Science, Multidisciplinary
Yuhan Liu, Hassan Shapourian, Paolo Glorioso, Shinsei Ryu
Summary: The paper discusses the obstruction of boundary theories of static bulk topological phases of matter and how quantum anomalies can be used for quantification and characterization. Specifically, it explores time-reversal symmetric boundary unitary operators in one and two spatial dimensions, and mixed anomalies between particle number conserving U(1) symmetry and discrete symmetries in odd spatial dimensions that can be realized at the boundaries of topological Floquet systems in even spatial dimensions.
Article
Quantum Science & Technology
Jonah Kudler-Flam, Vladimir Narovlansky, Shinsei Ryu
Summary: This work explores the distinguishability between random states and black hole microstates, calculating various generalized quantities to reveal new structures. Extending the study to random tensor networks leads to the discovery of new phenomena, enhancing the understanding of the relationship between holographic states and random tensor networks. The implications on the black hole information problem are discussed, providing new insights and solutions.
Article
Materials Science, Multidisciplinary
Ian MacCormack, Mao Tian Tan, Jonah Kudler-Flam, Shinsei Ryu
Summary: In this study, the growth and spreading of operators and entanglement in the many-body localized (MBL) phase and the random singlet phase (RSP) were characterized using the entanglement contour and multipartite operator entanglement measures. Slow scrambling behavior was found in the MBL phase, while the RSP phase showed nonscrambling behavior as a noninteracting model.
Article
Materials Science, Multidisciplinary
Hui Liu, Jhih-Shih You, Shinsei Ryu, Ion Cosma Fulga
Summary: We studied a non-Hermitian and nonunitary version of the two-dimensional Chalker-Coddington network model with balanced gain and loss, and found a contact effect induced by the skin effect in the two-terminal transmission, as well as an insulator to supermetal transition.
Article
Physics, Multidisciplinary
Jonah Kudler-Flam, Masahiro Nozaki, Shinsei Ryu, Mao Tian Tan
Summary: This study explores the robustness of quantum and classical information to perturbations implemented by local operator insertions, by computing multipartite entanglement measures in the Hilbert space of local operators. The research reveals the butterfly effect in quantum many-body systems and investigates membrane theory in Haar random unitary circuits to study the phenomenon of information delocalization caused by local operator insertions. Identical behavior is found in conformal field theories with holographic duals, while a limited amount of information is delocalized in free fermionic systems and random Clifford circuits.
PHYSICAL REVIEW RESEARCH
(2021)
Article
Materials Science, Multidisciplinary
Omer M. Aksoy, Jyong-Hao Chen, Shinsei Ryu, Akira Furusaki, Christopher Mudry
Summary: The stability of topological crystalline superconductors in symmetry class DIIIR and in two-dimensional space when perturbed by quartic contact interactions is investigated. The research shows that the presence of different numbers of Helical pairs of Majorana edge modes can be disrupted by interactions, leading to changes in the non-interacting classification. Analytical derivations of topological terms and the use of bosonization methods help understand the stability of edge theories with different numbers of edge modes.
Article
Physics, Particles & Fields
Ki-Seok Kim, Shinsei Ryu
Summary: By applying recursive renormalization group transformations to a scalar field theory, an effective quantum gravity theory with an emergent extra dimension is obtained. Dynamics of dual order-parameter field and metric tensor field originate from different effective interactions in the Gaussian level approximation. In the large N limit, quantum fluctuations of dynamical metric and dual scalar fields are suppressed, leading to a classical field theory in (D+1)-spacetime dimensions.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
