Article
Multidisciplinary Sciences
Xiyuan Lu, Mingkang Wang, Feng Zhou, Mikkel Heuck, Wenqi Zhu, Vladimir A. Aksyuk, Dirk R. Englund, Kartik Srinivasan
Summary: The authors demonstrate a method for generating orbital angular momentum (OAM) using photonic crystal ring resonators, while maintaining high cavity quality factors (up to 10^6). By ejecting high angular momentum states of a whispering gallery mode (WGM) microresonator through a grating-assisted mechanism, a scalable and chip-integrated solution for OAM generation is achieved.
NATURE COMMUNICATIONS
(2023)
Review
Physics, Multidisciplinary
D. E. Feldman, Bertrand Halperin
Summary: This article discusses the key features of the fractional quantum Hall effect, focusing on quasiparticles with fractional charge and statistics. It provides detailed definitions and methods for observing these properties, along with a review of current experimental status and discussions on non-Abelian statistics. The attempts to find experimental evidence for non-Abelian quasiparticles in certain quantum Hall systems are also explored.
REPORTS ON PROGRESS IN PHYSICS
(2021)
Article
Multidisciplinary Sciences
Cheng Chi, Qiao Jiang, Zhixin Liu, Liheng Zheng, Meiling Jiang, Han Zhang, Feng Lin, Bo Shen, Zheyu Fang
Summary: The study demonstrates selective manipulation of photon spin angular momentum at a deep subwavelength scale via electron-induced OSHE in Au nanoantennas, suggesting an information encoding scheme with robustness, privacy, and high level of integration for future quantum applications.
Article
Materials Science, Multidisciplinary
Zhaoyu Han, Jing-Yuan Chen
Summary: We construct a class of lattice Hamiltonians that can be solved controllably in their low-energy sectors through a combination of perturbative and exact techniques, circumventing the KapustinFidkowski no-go theorem. Our construction is generalizable.
Article
Nanoscience & Nanotechnology
L. S. Lima
Summary: The entanglement of magnons in the nearest-neighbor Heisenberg model on Lieb lattice with out-of-plane Dzyaloshinskii-Moriya antisymmetric spin coupling and external magnetic field is studied, analyzing the impact of magnon bands on quantum entanglement. Furthermore, quantum correlations in some fermions models such as the two-dimensional non-Hermitian model on LL lattice and the tight-binding model on the LL lattice have been analyzed, where the opening of the gap in the spectrum affects entanglement quantifiers.
PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES
(2022)
Article
Multidisciplinary Sciences
Tiancheng Zhang, Kaichen Dong, Jiachen Li, Fanhao Meng, Jingang Li, Sai Munagavalasa, Costas P. Grigoropoulos, Junqiao Wu, Jie Yao
Summary: In this work, a non-trivial twist-enabled coupling mechanism was identified and formulated in twisted bilayer photonic crystals, resulting in the generation of optical vortices. This study expands the field of moire photonics and opens up new possibilities for its applications.
NATURE COMMUNICATIONS
(2023)
Article
Physics, Multidisciplinary
T. Mueller, S. Diehl, M. Buchhold
Summary: We have identified an unconventional algebraic scaling phase in the quantum dynamics of long-range hopping free fermions under continuous local measurements. This phase exhibits features such as algebraic entanglement entropy growth and a slow algebraic decay of the density-density correlation function.
PHYSICAL REVIEW LETTERS
(2022)
Article
Quantum Science & Technology
Simon J. D. Phoenix, Faisal Shah Khan, Berihu Teklu
Summary: The production and manipulation of quantum correlation protocols is an active area of research, where the quantum nature of the correlation can be used to achieve properties unattainable in a classical framework. This work focuses on measuring the strength of correlation between quantum systems, with a special emphasis on multipartite systems.
QUANTUM INFORMATION PROCESSING
(2021)
Article
Quantum Science & Technology
Chitra Shukla, Priya Malpani, Kishore Thapliyal
Summary: This paper introduces research on hybrid entangled states and proposes an entanglement concentration protocol to obtain a maximally entangled hybrid Omega-type state, as well as discusses its application in quantum communication networks. It also mentions a scheme to apply it in hierarchical quantum teleportation networks, demonstrating the advantage of hybrid entangled states in bypassing Pauli operations.
QUANTUM INFORMATION PROCESSING
(2021)
Article
Physics, Multidisciplinary
Karl Pelka, Guilhem Madiot, Remy Braive, Andre Xuereb
Summary: Cavity optomechanical systems enable the manipulation of mechanical degrees of freedom with light. In this study, we demonstrate that temporally modulated driving can steer mechanical modes and induce transitions between different steady states. Our results also reveal the additional influence of thermo-optic nonlinearity on system dynamics.
PHYSICAL REVIEW LETTERS
(2022)
Article
Optics
Hang Liu, Kun Wang, Huifang Ma, Jingxiang Gao, Meng Liu, Huiyun Zhang, Yuping Zhang
Summary: This paper presents a cross-cross-shaped resonator based on a THz metasurface to generate an optical vortex (OV) beam in real space. By exploiting the polarization topology around the bound states in continuum (BIC), the merging of BIC at the point & UGamma; is achieved by tuning the width of the cross resonator, which improves the Q factor and enhances field localization. Moreover, the switching between high-order and low-order OV beam generator controlled by the merged BIC is realized, extending the application of BIC in modulating orbital angular momentum.
Article
Physics, Multidisciplinary
Ying-Hai Wu
Summary: This paper investigates the entanglement spectrum of non-Abelian anyons in two-dimensional systems with topological order. By studying the level counting in the entanglement spectrum and utilizing the edge theory of the Moore-Read state, we reveal the influence of the distribution of non-Abelian anyons on their fusion results.
Article
Physics, Multidisciplinary
Qin Jin, Hao Wang
Summary: In this study, we employed the principal component analysis (PCA) method to investigate bilayer fractional quantum Hall (FQH) systems considering the interlayer tunneling effect and Coulomb interaction. By utilizing common features in the PCA, we were able to recognize the transitions and boundaries between competing ground state phases, even in the absence of complete spectrum softening. Numerical evidence was provided to confirm the analogy between the bilayer system and its single-layer counterpart under large interlayer tunneling limit. The general approach with PCA was applied to determine the phase boundaries in strongly-correlated bilayer limit, decoupled bilayer limit, and strong interlayer tunneling limit, resulting in qualitatively similar phase diagrams as previous numerical studies without relying on explicit knowledge of the states. Therefore, our PCA study can be extended to other unfamiliar bilayer systems.
Article
Materials Science, Multidisciplinary
Benoit Sirois, Lucie Maude Fournier, Julien Leduc, William Witczak-Krempa
Summary: The study examines the quantum entanglement structure of integer quantum Hall states through the reduced density matrix of spatial subregions. It reveals geometric angle-dependent contributions and nearly identical angle dependencies to numerous conformal field theories (CFTs). Additionally, excitations localized near corners are observed in the low-lying entanglement spectrum.
Article
Materials Science, Multidisciplinary
Takuya Ito, Naokazu Shibata
Summary: The study focused on the edge states in fractional quantum Hall systems at filling factor nu = 1/3 using the density matrix renormalization group method. It was found that the density oscillation induced by local boundary conditions and the wave number of the minimum magnetoroton excitation play a key role in characterizing the edge structure. Additionally, changes in the confinement potential shape can lead to a partial reconstruction of this structure, while the stability of bulk states against variations in the number of electrons highlights the incompressibility of the bulk part of the fractional quantum Hall state.
Article
Physics, Multidisciplinary
Dumitru Calugaru, Aaron Chew, Luis Elcoro, Yuanfeng Xu, Nicolas Regnault, Zhi-Da Song, B. Andrei Bernevig
Summary: A new theoretical technique is introduced for identifying materials with flat bands and constructing perfectly flat bands. The study shows that these flat bands can lead to exotic phases and special properties, and are useful for investigating strong electron interactions.
Review
Nanoscience & Nanotechnology
Benjamin J. Wieder, Barry Bradlyn, Jennifer Cano, Zhijun Wang, Maia G. Vergniory, Luis Elcoro, Alexey A. Soluyanov, Claudia Felser, Titus Neupert, Nicolas Regnault, B. Andrei Bernevig
Summary: Solid-state materials have become a platform for exploring and manipulating topological phases, with the discovery of topological materials advancing rapidly from topological insulators and semimetals to higher-order topological crystalline insulators. Through the application of topological quantum chemistry and related methods, a large number of stoichiometric, solid-state, nonmagnetic materials have been found to possess topological properties. In the future, the identification and manipulation of topological phases in new materials can be further explored through the use of topological phase indicators.
NATURE REVIEWS MATERIALS
(2022)
Article
Multidisciplinary Sciences
Nicolas Regnault, Yuanfeng Xu, Ming-Rui Li, Da-Shuai Ma, Milena Jovanovic, Ali Yazdani, Stuart S. P. Parkin, Claudia Felser, Leslie M. Schoop, N. Phuan Ong, Robert J. Cava, Luis Elcoro, Zhi-Da Song, B. Andrei Bernevig
Summary: Researchers established the Materials Flatband Database website by analyzing and screening existing three-dimensional stoichiometric materials, and found 345 potential candidate materials with flat bands near the Fermi level, which are different from known engineered materials. Through experiments and theoretical analysis, they successfully explained the origin of flat bands in five representative materials.
Article
Physics, Multidisciplinary
Chunyu Guo, Lunhui Hu, Carsten Putzke, Jonas Diaz, Xiangwei Huang, Kaustuv Manna, Feng-Ren Fan, Chandra Shekhar, Yan Sun, Claudia Felser, Chaoxing Liu, B. Andrei Bernevig, Philip J. W. Moll
Summary: The concept of quasi-symmetry, which is a small deviation from exact symmetry, leads to topological materials with strong resilience to perturbations. Quasi-symmetries eliminate the need for fine tuning and enforce small gaps at low-symmetry points. The application of in-plane strain breaks crystal symmetry and gaps the degenerate points.
Article
Physics, Multidisciplinary
Ipsita Das, Cheng Shen, Alexandre Jaoui, Jonah Herzog-Arbeitman, Aaron Chew, Chang-Woo Cho, Kenji Watanabe, Takashi Taniguchi, Benjamin A. Piot, B. Andrei Bernevig, Dmitri K. Efetov
Summary: The discovery of flat bands with nontrivial band topology in magic-angle twisted bilayer graphene (MATBG) has provided a unique platform to study strongly correlated phenomena including superconductivity, correlated insulators, Chern insulators, and magnetism. The high magnetic field Hofstadter spectrum in MATBG reveals reentrant correlated insulators and interaction-driven Fermi-surface reconstructions, indicating a qualitatively new Hofstadter spectrum arising due to the strong electronic correlations in the reentrant flat bands.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
Jonah Herzog-Arbeitman, Valerio Peri, Frank Schindler, Sebastian D. Huber, B. Andrei Bernevig
Summary: Flat-band superconductivity theory demonstrates the importance of band topology to correlated phases, and applies the methods of topological quantum chemistry to superconducting states by deriving lower bounds for the superfluid weight. The research finds that obstructed bands can be distinguished from trivial bands in the presence of interactions by the nonzero lower bound imposed on their superfluid weight.
PHYSICAL REVIEW LETTERS
(2022)
Review
Physics, Multidisciplinary
Sanjay Moudgalya, B. Andrei Bernevig, Nicolas Regnault
Summary: This review provides a pedagogical introduction to and an overview of the exact results on weak ergodicity breaking via quantum many-body scars (QMBS) in isolated quantum systems. Various mechanisms and unifying formalisms for systems exhibiting QMBS are discussed, along with the connections to Hilbert space fragmentation.
REPORTS ON PROGRESS IN PHYSICS
(2022)
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
Multidisciplinary Sciences
Lun Jin, Nicodemos Varnava, Danrui Ni, Xin Gui, Xianghan Xu, Yuanfeng Xu, B. Andrei Bernevig, Robert J. Cava
Summary: Electronic structure calculations show that Sr2FeSbO6 double perovskite has a flat-band set just above the Fermi level, which includes contributions from ordinary subbands with weak kinetic electron hopping and a flat subband attributed to lattice geometry and orbital interference. Electron-doped Sr2-xLaxFeSbO6 samples (0 ≤ x ≤ 0.3) were synthesized to place the Fermi energy in that flat band, and their magnetism and crystal structures were analyzed. The dominant spin coupling changes from antiferromagnetic to ferromagnetic upon electron doping, but it remains unclear which subband or combination is responsible for this behavior.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2023)
Article
Materials Science, Multidisciplinary
Aaron Chew, Yijie Wang, B. Andrei Bernevig, Zhi-Da Song
Summary: We demonstrate the emergence of higher-order topological superconductivity in twisted bilayer graphene by introducing spin-singlet or spin-triplet superconductivity. The appearance of multiple copies of C2zT-protected Majorana Kramers pairs is observed at corners on pairing domain walls. The topological properties originate from the absence of a lattice support in the single-valley band structure of twisted bilayer graphene, which is protected by C2zT and approximate particle-hole symmetry P. We prove that any pairing term preserving valley-U(1), spin-SU(2), time-reversal, C2zT, and P can result in a higher-order topological superconductor. The stability of the corner states is verified even when P is weakly broken, which is applicable in experimental setups. Detection of these effects is proposed through the fractional Josephson effect in a TBG-TSC Josephson junction.
Article
Materials Science, Multidisciplinary
Lun-Hui Hu, Chunyu Guo, Yan Sun, Claudia Felser, Luis Elcoro, Philip J. W. Moll, Chao-Xing Liu, Andrei Bernevig
Summary: In this study, a hierarchical structure of quasisymmetries and their corresponding nodal structures in the chiral crystal material CoSi are revealed through two different approaches of perturbation expansions. Quasisymmetries are found to play a crucial role in the physical responses of the system and can protect the existence of nodal planes.
Article
Materials Science, Multidisciplinary
Jonah Herzog-Arbeitman, Aaron Chew, B. Andrei Bernevig
Summary: Bloch's theorem is crucial in topological band theory, but is broken by a perpendicular magnetic field, posing challenges in studying topological systems in strong flux. Moire materials have made this problem relevant in experiments, and this paper focuses on finding a solution. The authors construct a mathematical framework and analyze the behaviors of systems under 2n flux using a simple square lattice model and the Bistritzer-MacDonald Hamiltonian.
Article
Materials Science, Multidisciplinary
Kukka-Emilia Huhtinen, Jonah Herzog-Arbeitman, Aaron Chew, Bogdan A. Bernevig, Paivi Torma
Summary: A central result in superconductivity is that flat bands, though dispersionless, can still host a nonzero superfluid weight due to quantum geometry. We show that the derivation of the mean field superfluid weight in previous literature is incomplete, which can lead to severe quantitative and even qualitative errors. We derive the complete equations and demonstrate the relationship between the minimal quantum metric and the superfluid weight in isolated flat bands. We also provide an exact calculation of the Cooper pair mass in attractive Hubbard models and study the effect of closing the band gap between flat and dispersive bands.
Review
Physics, Applied
Paivi Torma, Sebastiano Peotta, Bogdan A. Bernevig
Summary: This article introduces the impact of quantum geometry on superconductivity and superfluidity in flat-band systems such as twisted graphene. It also compares ultracold gases as a complementary platform and discusses the prospects of twisted multilayer systems in achieving room-temperature superconductivity.
NATURE REVIEWS PHYSICS
(2022)