Publications
Research Highlights
(For a full list of publications and patents see below or go to Google Scholar, ORCID)
Exceptional point (EP) lies at the heart of various intriguing phenomena in optics, acoustics, and other nonconservative systems. We put forward a universal non-Abelian conservation rule governing the collective behaviors of multiple exceptional degeneracies in generic multiband non-Hermitian systems. We uncover two counterintuitive phenomena, including the path-dependent annihilation/coalescence of EPs and forbidden exceptional-line configurations. Our formalism assigns braid-valued invariants to the EPs/ELs as well as paths in the parameter space and sheds light on the versatile manipulations and applications based on exceptional degeneracies in nonconservative systems.
Cui-Xian Guo, Shu Chen, Kun Ding, & HH*
Phys. Rev. Lett. 130 (15), 157201 (2023)
Weyl semimetal is an archetypical gapless topological phase of matter. Here, we extend WSM to non-Hermitian regime and introduce the so-called point-gap WSM, where a pair of Weyl points are located on the imaginary axis of the complex energy plane (possessing different lifetimes). The generalization triggers a few fundamental changes to the topological characterization and dynamical response of WSMs. We predict a new effect, time-dependent current induced solely by magnetic field, that saturates at long time.
HH, Erhai Zhao, & W. Vincent Liu
Phys. Rev. B 106 (9), 094305 (2022)
We formulate a homotopy classification and knot theory of exceptional points and present a non-Hermitian no-go theorem governing the possible configurations of exceptional points and their splitting rules on a two-dimensional lattice.
HH*, Shikang Sun, & Shu Chen
Phys. Rev. Research 4, L022064 (2022)
Knots have a twisted history in quantum physics. We demonstrate that knots tied by the eigenenergy strings provide a complete topological classification of one-dimensional non-Hermitian Hamiltonians with separable bands. We show the transition between two phases characterized by distinct knots occur through exceptional points and come in two types. We develop an algorithm to construct the corresponding tight-binding non-Hermitian Hamiltonian for any desired knot, and propose a scheme to probe the knot structure via quantum quench.
HH & Erhai Zhao
Phys. Rev. Lett. 126, 010401 (2021)
Quench dynamics, time evolution after a sudden change in the Hamiltonian, studied under a new framework yields a collection of topological structures. Here we introduce the key concept of loop unitary constructed from the unitary time-evolution operator and show its homotopy invariant fully characterizes the dynamical topology. This opens up a systematic route to classify and characterize quantum quench dynamics.
HH & Erhai Zhao
Phys. Rev. Lett. 124, 160402 (2020), Editors’ Suggestion
We propose a versatile framework to dynamically generate Floquet higher-order topological insulators by multistep driving of topologically trivial Hamiltonians. Furthermore, we introduce dynamical topological invariants from the full unitary return map and show its phase bands contain Weyl singularities whose topological charges form dynamical multipole moments in the Brillouin zone.
HH, Biao Huang, Erhai Zhao, & W. Vincent Liu
Phys. Rev. Lett. 124, 057001 (2020)
We propose to realize a time-reversal invariant topological superfluid by utilizing s-wave pairing and emergent mirror and time-reversal symmetries in two coupled 1D ultracold atomic Fermi gases with spin-orbit coupling. By stacking such systems into 2D, we discover topological and Dirac-nodal superfluids hosting distinct MKP flat bands, which are stable against pairing fluctuations that otherwise annihilate Majorana pairs.
HH, Fan Zhang, & Chuanwei Zhang
Phys. Rev. Lett. 121, 185302 (2018)
A complete classification of triply degenerate points (semimetals) is given. Based on which, type-II (charge 1) and type-III (charge 0) triply degenerate topological semimetals are predicted. An experimental scheme utilizing spin-tensor- and spin-vector-momentum couplings in cold-atom optical lattice is proposed to realize all the three types of triply degenerate semimetals.
HH, Junpeng Hou, Fan Zhang, & Chuanwei Zhang
Phys. Rev. Lett. 120, 240401 (2018)
The fundermental task of condensed-matter physics is the search of novel quantum states of matter. Here, we demonstrate the existence of a novel quantum order, dubbed superfluid-quasicrystals. We show the emergent superfluid-quasicrystal stripe state with the minimal fivefold rotational symmetry can be realized as the ground state of a Bose-Einstein condensate within a practical experimental scheme.
Junpeng Hou, HH, Kuei Sun, & Chuanwei Zhang
Phys. Rev. Lett. 120, 060407 (2018)
See also Newsweek , ScienceDaily , Phys.org .
Full List of publications
Liouvillian skin effect in a one-dimensional open many-body quantum system with generalized boundary conditions
Liang Mao, Ming-Jie Tao, HH, & Lei Pan
ArXiv: 2401.15614 (2024)
Anderson transition and mobility edges on hyperbolic lattices
Tianyu Li, Yi Peng, Yucheng Wang*, & HH*
ArXiv: 2312.12857 (2023)
Graph Morphology of Non-Hermitian Bands
Yuncheng Xiong & HH*
ArXiv: 2311.14921 (2023)
Floquet non-Abelian topological insulator and multifold bulk-edge correspondence
Tianyu Li & HH*
Nature Communications 14, 6418 (2023)
Non-Hermitian band theory in all dimensions: uniform spectra and skin effect
HH
ArXiv: 2306.12022 (2023)
Anomalous second-order skin modes in Floquet non-Hermitian systems
Chun-Hui Liu, HH, Shu Chen, & Xiongjun Liu*
ArXiv: 2303.11259 (2023)
Accumulation of scale-free localized states induced by local non-Hermiticity
Cui-Xian Guo, Xueliang Wang, HH*, & Shu Chen *
Phys. Rev. B 107, 134121 (2023), Editors’ Suggestion
Exceptional Non-Abelian Topology in Multiband Non-Hermitian Systems
Cui-Xian Guo, Shu Chen, Kun Ding, & HH*
Phys. Rev. Lett. 130 (15), 157201 (2023)
Dynamical signatures of point-gap Weyl semimetal
HH, Erhai Zhao, & W. Vincent Liu
Phys. Rev. B 106 (9), 094305 (2022)
Localization, multifractality, and many-body localization in periodically kicked quasiperiodic lattices
Yu Zhang, Bozhen Zhou, HH, & Shu Chen
Phys. Rev. B 106 (5), 054312 (2022)
Symmetry and topological classification of Floquet non-Hermitian systems
Chun-Hui Liu, HH*, & Shu Chen
Physical Review B 105 (21), 214305 (2022)
Knot topology of exceptional point and non-Hermitian no-go theorem
HH*, Shikang Sun, & Shu Chen
Phys. Rev. Research 4, L022064 (2022)
Illuminating the bulk-boundary correspondence of a non-Hermitian stub lattice with Majorana stars
James Bartlett, HH, & Erhai Zhao
Phys. Rev. B 104, 195131 (2021)
Knots and Non-Hermitian Bloch Bands
HH & Erhai Zhao
Phys. Rev. Lett. 126, 010401 (2021)
Tuning the topology of p-wave superconductivity in an analytically solvable two-band model
HH, Erhai Zhao, & Indubala I. Satija
Phys. Rev. B 102, 235156 (2020)
Topological phases in spin-1 Fermi gases with two-dimensional spin-orbit coupling
Junpeng Hou, HH, & Chuanwei Zhang
Phys. Rev. A 101, 053613 (2020)
Quench dynamics of Hopf insulators
HH, Chao Yang, & Erhai Zhao
Phys. Rev. B 101, 155131 (2020)
Topological Invariants for Quantum Quench Dynamics from Unitary Evolution
HH & Erhai Zhao
Phys. Rev. Lett. 124, 160402 (2020), Editors’ Suggestion
Dynamical Singularities of Floquet Higher-Order Topological Insulators
HH, Biao Huang, Erhai Zhao, & W. Vincent Liu
Phys. Rev. Lett. 124, 057001 (2020)
Chiral and counter-propagating Majorana fermion in a p-wave superconductor
HH, Indubala Satija, & Erhai Zhao
New J. Phys. 21, 123014 (2019)
Topological Mott insulator with bosonic edge modes in one-dimensional fermionic superlattices
HH, Shu Chen, Tian-Sheng Zeng, & Chuanwei Zhang
Phys. Rev. A 100, 023616 (2019)
Effect of incommensurate potential on nodal-link semimetals
Yucheng Wang, HH, & Shu Chen
Phys. Rev. B 98, 205410 (2018)
Majorana Doublets, Flat Bands, and Dirac Nodes in s-Wave Superfluids
HH, Fan Zhang, & Chuanwei Zhang
Phys. Rev. Lett. 121, 185302 (2018)
Spin-1 topological monopoles in parameter space of ultracold atoms
HH & Chuanwei Zhang
Phys. Rev. A 98, 013627 (2018)
Topological Triply Degenerate Points Induced by Spin-Tensor-Momentum Couplings
HH, Junpeng Hou, Fan Zhang, & Chuanwei Zhang
Phys. Rev. Lett. 120, 240401 (2018)
Superfluid-Quasicrystal in a Bose-Einstein Condensate
Junpeng Hou, HH, Kuei Sun, & Chuanwei Zhang
Phys. Rev. Lett. 120, 060407 (2018)
Exact ordering of energy levels for one-dimensional interacting Fermi gases with SU(N) symmetry
Lei Pan, Yanxia Liu, HH, Yunbo Zhang, & Shu Chen
Phys. Rev. B 96, 075149 (2017)
Strongly interacting one-dimensional quantum gas mixtures with weak p-wave interactions
HH, Lei Pan, & Shu Chen
Phys. Rev. A 93, 033636 (2016)
Fractional topological states in quantum spin chains with periodical modulation
HH, Huaiming Guo, & Shu Chen
Phys. Rev. B 93, 155133 (2016)
Strongly interacting Bose-Fermi mixtures in one dimension
HH, Liming Guan, & Shu Chen
New J. Phys. 18, 025009 (2016), Invited Focus Issue Article.
Many-body ground state localization and coexistence of localized and extended states in an interacting quasiperiodic system
Yucheng Wang, HH, & Shu Chen
Eur. Phys. J. B 89, 77 (2016)
Spin-orbit coupled s-wave superconductor in one dimensional optical lattice
Lijun Yang, Lijun Lang, Rong Lv, & HH
Commun. Theor. Phys. 63, 445(2015)
Topological incommensurate magnetization plateaus in quasi-periodic quantum spin chains
HH, Chen Cheng, Honggang Luo, & Shu Chen
Scientific Reports 5, 8433 (2015)
Topological nature of magnetization plateaus in periodically modulated quantum spin chains
HH, Chen Cheng, Zhihao Xu, Honggang Luo, & Shu Chen
Phys. Rev. B 90, 035150 (2014)
Ferromagnetic to antiferromagnetic transition of one-dimensional spinor Bose gases with spin-orbit coupling
Xing Chen, HH, Yuzhu Jiang, & Shu Chen
Eur. Phys. J. D 7, 166 (2013)
Phase diagram and topological superfluid state of spin-orbit coupled Fermi gas with attractive interactions in a one-dimensional optical lattice
HH, Chen Cheng, Yucheng Wang, Honggang Luo, & Shu Chen
arXiv 1511.01762
Mapping trapped atomic gas with spin-orbit coupling to quantum Rabi-like model
HH & Shu Chen
ArXiv 1302.5933