Article
Physics, Multidisciplinary
Chengyu Wang, A. Gupta, S. K. Singh, Y. J. Chung, L. N. Pfeiffer, K. W. West, K. W. Baldwin, R. Winkler, M. Shayegan
Summary: In this study, a new and unexpected even-denominator FQHS was observed in a high-quality GaAs 2D hole system at filling factor v = 3/4. This FQHS is observed in the lowest Landau level and exhibits non-Abelian characteristics.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
Li Qing-Xin, Huang Yan, Chen Yi-Wei, Zhu Yu-Jian, Zhu Wang, Song Jun-Wei, An Dong-Dong, Gan Qi-Kang, Wang Kai-Yuan, Wang Hao-Lin, Mai Zhi-Hong, Andy Shen, Xi Chuan-Ying, Zhang Jing-Lei, Yu Ge-Liang, Wang Lei
Summary: In this study, the electric transport behavior of bilayer graphene under electric and magnetic fields was investigated using high-quality bilayer graphene/hBN heterostructure. The observed even-denominator fractional quantum Hall state exhibits non-Abelian statistics, indicating its potential for topological quantum computation.
ACTA PHYSICA SINICA
(2022)
Article
Physics, Applied
Yasuaki Hayafuchi, Ryota Konno, Annisa Noorhidayati, Mohammad Hamzah Fauzi, Naokazu Shibata, Katsushi Hashimoto, Yoshiro Hirayama
Summary: The 3/2 diagonal resistance discovered in a nanometer-sized triple-gated quantum point contact on a high-mobility single-layer two-dimensional GaAs wafer highlights the potential of even-denominator states in future quantum technologies. The crucial role of the center gate in realizing the QPC's 3/2 state and the use of conventional QPC devices as building blocks for semiconductor quantum devices signify a new path for the development of semiconductor-based quantum technologies.
APPLIED PHYSICS EXPRESS
(2022)
Article
Physics, Multidisciplinary
Md. Shafayat Hossain, Meng K. Ma, Y. J. Chung, S. K. Singh, A. Gupta, K. W. West, K. W. Baldwin, L. N. Pfeiffer, R. Winkler, M. Shayegan
Summary: We report the observation of a 1/2 fractional quantum Hall state in a high-quality two-dimensional electron system. The properties of this state can be controlled by applying strain and changing the magnetic field, allowing for phase transitions and tunability.
PHYSICAL REVIEW LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Mohammad Atif Javed, Jakob Schwibbert, Roman-Pascal Riwar
Summary: Fractionally charged excitations are important in condensed matter physics and can be detected through different means. The relationship between dissipationless supercurrents and dissipative transport is not fully understood when both of them coincide. In this study, we explore the dynamics of a system-detector using a Lindbladian that captures both coherent and dissipative transport, and show that even conventional superconductor-normal metal hybrid circuits exhibit various topological phases, including a fractional Josephson effect.
Article
Materials Science, Multidisciplinary
Wenchen Luo, Shenglin Peng, Hao Wang, Yu Zhou, Tapash Chakraborty
Summary: The mixing of Landau levels is crucial in determining the nature of the ground state in the fractional quantum Hall effect. The stability of the ground state at filling factor 5/2 in strong Landau-level-mixed systems is addressed, with a proposed approach involving screening and thickness effect explaining recent experiments. Phase diagrams show that phase transitions can be observed by tuning the magnetic field and quantum well width, with predictions for incompressibility in higher Landau levels in another mixed system.
Article
Physics, Multidisciplinary
Gabor B. Halasz
Summary: This study proposes a signature to identify spin-triplet superconductors in mesoscopic rings based on the magnetoresistance oscillations related to flux quantisation. The presence of half-quantum vortices in spin-triplet superconductors could be a platform for topological quantum computation. By studying magnetoresistance oscillations resulting from thermal vortex tunneling in spin-triplet superconducting rings, this research finds fractional periodicity oscillations that confirm the spin-triplet nature of superconductivity and reveal the tunneling of half-quantum vortices in real-world candidate materials.
COMMUNICATIONS PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Mehdi Hatefipour, Joseph J. Cuozzo, Jesse Kanter, William M. Strickland, Christopher R. Allemang, Tzu-Ming Lu, Enrico Rossi, Javad Shabani
Summary: In this work, the results of InAs quantum wells placed near superconducting NbTiN are presented. Negative downstream resistance and reduction of Hall resistance indicate high efficiency Andreev conversion. Analysis of experimental data reveals that the high transparency of the InAs/NbTiN interface plays a crucial role in the efficient Andreev conversion.
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
Physics, Multidisciplinary
Deepak Gaur, Hrushikesh Sable, D. Angom
Summary: In this research, we investigate the bosonic fractional quantum Hall (FQH) states in a two-dimensional optical lattice with a synthetic magnetic field, described by the bosonic Harper-Hofstadter Hamiltonian. We utilize cluster Gutzwiller mean-field and exact diagonalization techniques to study these states. We observe incompressible states resembling FQH states at various filling factors. Our particular focus is on the nu = 1/2 FQH state, characterized by the two-point correlation function and the many-body Chern number. Furthermore, we examine the impact of dipolar interaction on the nu = 1/2 FQH state, finding that it stabilizes the FQH state against the competing superfluid state.
FRONTIERS IN PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Yen-Wen Lu, Prashant Kumar, Michael Mulligan
Summary: Standard field theoretic formulations of composite fermion theories for anomalous metals are not Galilean invariant and require correction terms. This study investigates the effect of the dipole term in the Dirac composite fermion theory on quantum oscillations in electrical resistivity and finds it inadequate to explain the systematic discrepancy between theory and experiment. Additionally, the behavior of quantum oscillations at half-filled and quarter-filled lowest Landau levels are found to be qualitatively similar.
Article
Physics, Multidisciplinary
Bo Yang, Ajit C. Balram
Summary: The study extends local exclusion conditions (LECs) from the ground state to construct the elementary excitations of quasiholes and quasielectrons in fractional quantum Hall (FQH) phases. It is found that the undressed quasielectron excitations obtained from LECs are topologically equivalent to those from composite fermion theory, revealing interesting connections between different FQH phases.
NEW JOURNAL OF PHYSICS
(2021)
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
Materials Science, Multidisciplinary
Rong-Chun Ge, Michael Kolodrubetz
Summary: The goal is to realize novel phases of matter with topological order using superconducting circuits and other artificial quantum systems. By creating nearly flat topological bands on small lattices, it is possible to observe fingerprints of fractionalization through charge pumping with as few as 24 lattice sites. The proposal suggests using a finite lattice of superconducting qubits with cylindrical connectivity on triangular and square lattices to implement the concept.
Article
Multidisciplinary Sciences
Dawei Zhai, Cong Chen, Cong Xiao, Wang Yao
Summary: The authors find that interlayer hopping in twisted bilayers allows for a linear charge Hall effect under time reversal symmetry, which is typically forbidden by the Onsager relation. This effect is achieved through interfacial coupling and a twisted stacking, which fulfills the overall chiral symmetry requirement. The research demonstrates this effect in twisted bilayer graphene and twisted homobilayer transition metal dichalcogenides, showing giant Hall ratios under experimentally practical conditions and gate voltage control.
NATURE COMMUNICATIONS
(2023)
Article
Physics, Multidisciplinary
Sankar Das Sarma
Summary: Majorana particles, which are the same as their antiparticles, show promise for quantum computing in condensed matter systems. This article discusses the search for Majorana modes in semiconductor heterostructures and the limitations imposed by disorder. Majorana zero modes are emergent phenomena in topological superconductors, and this Perspective provides an overview of their physics, recent experimental progress, and future outlook for success.
Article
Physics, Multidisciplinary
DinhDuy Vu, Sankar Das Sarma
Summary: An ergodic system subjected to an external periodic drive will be heated to infinite temperature, but this heating can be stopped during a prethermal period if the applied frequency is larger than the typical energy scale of the local Hamiltonian. This prethermal period exhibits an emergent symmetry that, if broken, leads to subharmonic oscillation of the discrete time crystal (DTC). The presence of dissipation affects the survival time of the prethermal DTC, with a bath coupling prolonging the prethermal period and interaction with the environment destabilizing spontaneous symmetry breaking, resulting in a nonmonotonic variation of the survival time.
PHYSICAL REVIEW LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Jiabin Yu, Ming Xie, Fengcheng Wu, Sankar Das Sarma
Summary: Signatures of nematic nodal superconductivity have been observed in magic angle twisted bilayer graphene. Researchers propose a general topological mechanism explaining how nematic pairing leads to nodal superconductivity in this material.
Article
Materials Science, Multidisciplinary
Prathyush P. Poduval, Sankar Das Sarma
Summary: We theoretically investigate the issue of doping induced insulator to metal transition in bulk semiconductors by analyzing the density-dependent mean free path and the Anderson localization transition controlled by the Ioffe-Regel-Mott (IRM) criterion. We calculate the mean free path on the highly doped metallic side considering carrier scattering by ionized dopants. The Coulomb disorder of the charged dopants is screened by the carriers themselves, leading to an integral equation for localization. By solving this equation analytically and numerically, we provide detailed results for the critical density of the doping induced metal-insulator transition.
Article
Materials Science, Multidisciplinary
Nathan L. Foulk, Sankar Das Sarma
Summary: We demonstrate the potential realization of quantum Floquet matter, particularly the discrete time crystal (DTC), using modern silicon spin qubits based in quantum dots. This is significant as silicon spin qubits have advantages in dealing with charge noise. We show the differences between prethermal phenomena and true time-crystalline spatiotemporal order, and illustrate rich regime structures in a spin chain of four qubits that are distinct from the thermal regime.
Article
Materials Science, Multidisciplinary
Seth M. Davis, Yang-Zhi Chou, Fengcheng Wu, Sankar Das Sarma
Summary: We calculate the theoretical contribution of scattering by acoustic phonons to the doping and temperature dependence of electrical resistivity in Bernal bilayer graphene (BBG) and rhombohedral trilayer graphene (RTG). The nontrivial geometric features of the band structures of these systems strongly influence the resistivity's temperature and doping dependencies. Our focus on BBG and RTG is motivated by recent experiments in these systems that have discovered exotic low-temperature superconductivity. The understanding of the influence of band geometry on transport is crucial in these systems.
Article
Materials Science, Multidisciplinary
Haining Pan, Sankar Das Sarma
Summary: Motivated by the presence of Majorana zero modes in both the Kitaev chain model and the experimental semiconductor-superconductor Majorana nanowire, this theoretical study investigates the equivalence or similarity between the two models from the perspective of their corresponding dual spin models. By using the Jordan-Wigner transformation, the duality between the Kitaev chain and the transverse-field XY spin model is established, aiming to connect the Kitaev chain and the nanowire. The application of the Jordan-Wigner transformation to the nanowire reveals that the corresponding bosonic spin model is a generalized spin cluster model with staggered couplings. By projecting out the higher energy band of the spinful nanowire system, an effective low-energy spinless system is obtained, leading to the connection between the Kitaev chain and Majorana nanowire.
Article
Materials Science, Multidisciplinary
Yi-Ting Tu, Sankar Das Sarma
Summary: We analyze an experimental work which shows the failure of the Wiedemann-Franz law in graphene at low temperatures, attributing this failure to the non-Fermi liquid nature of the Dirac fluid. Despite theoretical efforts, the observations remain unexplained. Our analysis suggests that the opening of a gap at the Dirac point induced by the substrate may explain the results. Further experiments are needed to resolve the issue and determine the role of electron and hole transport in the presence of disorder and phonons.
Article
Materials Science, Multidisciplinary
Yi-Ting Tu, DinhDuy Vu, S. Das Sarma
Summary: Coupling a one-dimensional quasiperiodic interacting system to a Markovian bath, this study investigates the avalanche instability of the many-body localized phase numerically. The results show that many-body localization (MBL) is more stable in pseudorandom quasiperiodic systems than in randomly disordered systems for a disorder strength W > 8, potentially up to arbitrarily large system sizes. Real-space RG arguments support this conclusion and a detailed comparison between quasiperiodic and random MBL from the avalanche instability perspective reveals that they belong to different universality classes.
Article
Materials Science, Multidisciplinary
Donovan Buterakos, Sankar Das Sarma
Summary: We discuss interesting phenomena in the Hubbard model related to flat-band ferromagnetism. The first is a mathematical theorem that describes the conditions for degeneracy between a flat-band ferromagnetic and a nonferromagnetic state. This theorem is generally applicable and independent of geometry, but only holds for a small number of holes in a filled band. The second phenomenon challenges intuition by showing an example where particles do not prefer to doubly occupy low-energy states before filling higher-energy states. Lastly, we present a pattern of ferromagnetism in small pentagonal and hexagonal plaquettes at specific filling factors. These examples can be observed in quantum dot arrays available in laboratories.
Article
Materials Science, Multidisciplinary
Seongjin Ahn, Sankar Das Sarma
Summary: This theoretical study validates the experimentally observed sudden change in 2D resistivity with a spontaneous valley polarization transition from 2 to 1 at the critical density, showing quantitative consistency between the two.
Article
Materials Science, Multidisciplinary
Haining Pan, Sankar Das Sarma
Summary: Motivated by recent experiments, this study proposes an alternative mechanism through theoretical simulations to explain the generation of large zero-bias conductance peaks in Majorana nanowires. The mechanism includes three conditions: strong potential disorder in the nanowire bulk, suppression of disorder near the wire ends, and low tunnel barrier strength. These conditions are often satisfied in experiments, thereby explaining the observed large zero-bias conductance peaks.
Article
Materials Science, Multidisciplinary
Jiabin Yu, Yu-An Chen, Sankar Das Sarma
Summary: This study generalizes the topologically obstructed pairings between Chern states by proposing Euler obstructed Cooper pairing in 3D systems. The Euler obstructed pairing widely exists between two Fermi surfaces with nontrivial band topology and can lead to nodal superconductivity and hinge Majorana zero modes under certain conditions.
Article
Materials Science, Multidisciplinary
Yang-Zhi Chou, Fengcheng Wu, Jay D. Sau, Sankar Das Sarma
Summary: This article presents a systematic theory of acoustic-phonon-mediated superconductivity that incorporates Coulomb repulsion and explains recent experiments in Bernal bilayer graphene. The theory predicts that s-wave spin-singlet and f-wave spin-triplet pairings are degenerate and dominant. The results indicate that the observed spin-triplet superconductivity in Bernal bilayer graphene arises from acoustic phonons.
Article
Materials Science, Multidisciplinary
Seongjin Ahn, Sankar Das Sarma
Summary: We developed a minimal theory for the metal-insulator transition observed in two-dimensional moire multilayer transition metal dichalcogenides, attributing it to Coulomb disorder in the environment. Carrier scattering by random charged impurities leads to an effective 2D MIT roughly controlled by the Ioffe-Regel criterion, with necessary random charged impurity content consistent with known levels in TMDs.