Quantum transport in non-Hermitian impurity arrays

Zhang, K. L.; Yang, X. M.; Song, Z.

doi:10.1103/physrevb.100.024305

Cited by 13 publications

(9 citation statements)

References 52 publications

(41 reference statements)

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“…In that regard we point the related but different proposal in Ref. [66], where the formation of bound states inside the band gap due to a PT -symmetric imaginary potential in strongly coupled bilayer lattices was considered. We also discuss experimental feasibility of non-Hermitian impurity in electronic and photonic systems.…”

Section: Introductionmentioning

confidence: 67%

“…The focus of this study is the non-Hermitian effects in Dirac matter, e.g., in photonic graphene. Motivated by experimental [27,65] and recent theoretical [34,66,67] studies in optical non-Hermitian systems, we investigate the effects of non-Hermitian defects in 2D and 3D Dirac systems. In particular, we show how the presence of the imaginary part of defect potential affects the spatial distribution of the LDOS and changes the frequency dependence of the DOS.…”

Section: Introductionmentioning

confidence: 99%

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Non-Hermitian impurities in Dirac systems

Sukhachov

Balatsky

2020

Phys. Rev. Research

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Quasiparticle states in Dirac systems with complex impurity potentials are investigated. It is shown that an impurity site with loss leads to a nontrivial distribution of the local density of states (LDOS). While the real part of defect potential induces a well-pronounced peak in the density of states (DOS), the DOS is either weakly enhanced at small frequencies or even forms a peak at the zero frequency for a lattice in the case of non-Hermitian impurity. As for the spatial distribution of the LDOS, it is enhanced in the vicinity of impurity but shows a dip at a defect itself when the potential is sufficiently strong. The results for a two-dimensional hexagonal lattice demonstrate the characteristic trigonal-shaped profile for the LDOS. The latter acquires a double-trigonal pattern in the case of two defects placed at neighboring sites. The effects of non-Hermitian impurities could be tested both in photonic lattices and certain condensed matter setups. * pavlo.sukhachov@su.se † avb@nordita.org

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Section: Introductionmentioning

confidence: 67%

Section: Introductionmentioning

confidence: 99%

Non-Hermitian impurities in Dirac systems

Sukhachov

Balatsky

2020

Phys. Rev. Research

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“…In addition to the rather familiar optical lattice and waveguide array platforms, such 2D non-Hermitian Floquet system could be also realized with circuits and nonreciprocal electrical elements or in discrete-time nonunitary quantum-walk system 70,[85][86][87] . Note also that in the high-frequency limit T → 0 (with T 1 = T 2 ), the Floquet effective Hamiltonian H i eff is simply given by (H 1 + H 2 )/2, which in the coordinate space represents a tight-binding bilayer square lattice 93 . In that limit the EPs always occur at either k x = 0, π or k y = 0, π.…”

Section: Model: 2d Non-hermitian Floquet Systemmentioning

confidence: 99%

Non-Hermitian Floquet topological phases: Exceptional points, coalescent edge modes, and the skin effect

2020

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Periodically driven non-Hermitian systems can exhibit rich topological band structure and non-Hermitian skin effect, without analogs in their static or Hermitian counterparts. In this work we investigate the exceptional band-touching points in the Floquet quasi-energy bands, the topological characterization of such exceptions points and the Floquet non-Hermitian skin effect (FNHSE). Specifically, we exploit the simplicity of periodically quenched two-band systems in one dimension or two dimensions to analytically obtain the Floquet effective Hamiltonian as well as locations of the many exceptional points possessed by the Floquet bulk bands. Two different types of topological winding numbers are used to characterize the topological features. Bulk-edge correspondence (BBC) is naturally found to break down due to FNHSE, which can be drastically different among different bulk states. Remarkably, given the simple nature of our model systems, recovering the BBC is doable in practice only for certain parameter regime where a low-order truncation of the characteristic polynomial (which determines the Floquet band structure) becomes feasible. Furthermore, irrespective of which parameter regime we work with, we find a number of intriguing aspects of Floquet topological zero modes and π modes. For example, under the open boundary condition zero edge modes and π edge modes can individually coalesce and localize at two different boundaries. These anomalous edge states can also switch their accumulation boundaries when certain system parameter is tuned. These results indicate that non-Hermitian Floquet topological phases, though more challenging to understand than their Hermitian counterparts, can be extremely rich in the presence of FNHSE. arXiv:1909.10234v1 [cond-mat.mes-hall]

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“…Non-Hermitian systems occur in various fields of physics and are experimentally accessible [1][2][3][4][5][6][7][8][9][10]. Many fascinating phenomena related to non-Hermiticity were discovered in, e.g., topological systems [11][12][13][14][15], many-body systems [16,17], adiabatic passage [18][19][20][21][22][23], nonreciprocal scattering [24][25][26], and localizationdelocalization transitions [27][28][29][30]. Many works have introduced non-Hermiticity to well-known systems, especially those already shown to have novel properties in the Hermitian cases.…”

Section: Introductionmentioning

confidence: 99%

Work statistics in non-Hermitian evolutions with Hermitian endpoints

Zhou,

You,

Nori

2021

Preprint

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Non-Hermitian systems with specific forms of Hamiltonians can exhibit novel phenomena. However, it is difficult to study their quantum thermodynamical properties. In particular, the calculation of work statistics can be challenging in non-Hermitian systems due to the change of state norm. To tackle this problem, we modify the two-point measurement method in Hermitian systems. The modified method can be applied to non-Hermitian systems which are Hermitian before and after the evolution. In Hermitian systems, our method is equivalent to the two-point measurement method. When the system is non-Hermitian, our results represent a projection of the statistics in a larger Hermitian system. As an example, we calculate the work statistics in a non-Hermitian Su-Schrieffer-Heeger model. Our results reveal several differences between the work statistics in non-Hermitian systems and the one in Hermitian systems.

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Quantum transport in non-Hermitian impurity arrays

Cited by 13 publications

References 52 publications

Non-Hermitian impurities in Dirac systems

Non-Hermitian impurities in Dirac systems

Non-Hermitian Floquet topological phases: Exceptional points, coalescent edge modes, and the skin effect

Work statistics in non-Hermitian evolutions with Hermitian endpoints

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