Floquet second-order topological insulators in non-Hermitian systems

Wu, Hong; Wang, Baoqin; An, Jing

doi:10.1103/physrevb.103.l041115

Cited by 42 publications

(17 citation statements)

References 83 publications

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“…In recent years, possible new phases that could emerge due to the interplay between Floquet drivings and non-Hermitian effects are considered. Theoretical progresses have been made to the discovery of non-Hermitian Floquet topological insulators [34][35][36][37][38][39][40][41][42][43][44], second-order topological phases [45,46], topological superconductors [47,48] and semimetals [49][50][51][52]. Intriguing features such as non-Hermiticity induced Floquet topological edge states [45] and their coexistence with Floquet non-Hermitian skin effects [41] have also been uncovered.…”

Section: Introductionmentioning

confidence: 99%

Driving-induced multiple ${\cal PT}$-symmetry breaking transitions and reentrant localization transitions in non-Hermitian Floquet quasicrystals

Zhou,

Han

2022

Preprint

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The cooperation between time-periodic driving fields and non-Hermitian effects could endow systems with distinctive spectral and transport properties. In this work, we uncover an intriguing class of non-Hermitian Floquet matter in one-dimensional quasicrystals, which is characterized by the emergence of multiple driving-induced PT -symmetry breaking/restoration, mobility edges, and reentrant localization transitions. These findings are demonstrated by investigating the spectra, level statistics, inverse participation ratios and wavepacket dynamics of a periodically quenched nonreciprocal Harper model. Our results not only unveil the richness of localization phenomena in driven non-Hermitian quasicrystals, but also highlight the advantage of Floquet approach in generating unique types of nonequilibrium phases in open systems.

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Section: Introductionmentioning

confidence: 99%

Driving-induced multiple ${\cal PT}$-symmetry breaking transitions and reentrant localization transitions in non-Hermitian Floquet quasicrystals

Zhou,

Han

2022

Preprint

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“…Despite the intriguing features above, the existing framework for Floquet topological phases mainly concerns non-dissipative Hermitian processes, although the system can exchange energy and particles with the external driven field. In addition, there has been growing interest in non-Hermitian systems 21,22 , especially topological physics [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] . When a lattice system is engaged with spacial asymmetric tunneling, not only the edge modes but also the bulk states can pile up at one side, which is known as the skin effect [39][40][41] .…”

mentioning

confidence: 99%

Non-Floquet engineering in periodically driven non-Hermitian systems

Wang,

Zhao,

Zhuang

et al. 2021

Preprint

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Floquet engineering, modulating quantum systems in a time periodic way, lies at the central part for realizing novel topological dynamical states. Thanks to the Floquet engineering, various new realms on experimentally simulating topological materials have emerged. Conventional Floquet engineering, however, only applies to time periodic non-dissipative Hermitian systems, and for the quantum systems in reality, non-Hermitian process with dissipation usually occurs. So far, it remains unclear how to characterize topological phases of periodically driven non-Hermitian systems via the frequency space Floquet Hamiltonian. Here, we propose the non-Floquet theory to identify different Floquet topological phases of time periodic non-Hermitian systems via the generation of Floquet band gaps in frequency space. In non-Floquet theory, the eigenstates of non-Hermitian Floquet Hamiltonian are temporally deformed to be of Wannier-Stark localization. Remarkably, we show that different choices of starting points of driving period can result to different localization behavior, which effect can reversely be utilized to design detectors of quantum phases in dissipative oscillating fields. Our protocols establish a fundamental rule for describing topological features in non-Hermitian dynamical systems and can find its applications to construct new types of Floquet topological materials.

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“…Recently, considerable efforts have been devoted to explore topological phases in non-Hermitian extensions of topological insulators and semimetals [89][90][91][92][93][94][95][96][97][98][99], including non-Hermitian higher-order topological insulators [100][101][102][103][104][105][106][107]. Non-Hermiticity originated from dissipation in open classical and quantum systems [83,87], and the inclusion of non-Hermitian features in topological systems can give rise to unusual topological properties and novel topological phases without Hermitian counterparts.…”

mentioning

confidence: 99%

Higher-Order Weyl-Exceptional-Ring Semimetals

Liu,

He,

Yang

et al. 2021

Preprint

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For first-order topological semimetals, non-Hermitian perturbation can drive the Weyl nodes into Weyl exceptional rings having multiple topological structures and no Hermitian counterparts. Recently, it was discovered that higher-order Weyl semimetals, as a novel class of higher-order topological phases, can uniquely exhibit coexisting surface and hinge Fermi arcs. However, non-Hermitian higher-order topological semimetals have not yet been explored. Here, we identify a new type of topological semimetals, i.e, a higher-order topological semimetal with Weyl exceptional rings. In such a semimetal, these rings are characterized by both a spectral winding number and a Chern number. Moreover, the higher-order Weyl-exceptional-ring semimetal supports both surface and hinge Fermi-arc states, which are bounded by the projection of the Weyl exceptional rings onto the surface and hinge, respectively. Our studies open new avenues for exploring novel higher-order topological semimetals in non-Hermitian systems.

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Floquet second-order topological insulators in non-Hermitian systems

Cited by 42 publications

References 83 publications

Driving-induced multiple ${\cal PT}$-symmetry breaking transitions and reentrant localization transitions in non-Hermitian Floquet quasicrystals

Driving-induced multiple ${\cal PT}$-symmetry breaking transitions and reentrant localization transitions in non-Hermitian Floquet quasicrystals

Non-Floquet engineering in periodically driven non-Hermitian systems

Higher-Order Weyl-Exceptional-Ring Semimetals

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