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We show how generic non-Hermitian tight-binding lattice models can be realized in an unconditional, quantum-mechanically consistent manner by constructing an appropriate open quantum system. We focus on the quantum steady states of such…

Quantum Physics · Physics 2022-02-21 Alexander McDonald , Ryo Hanai , Aashish A. Clerk

The metric associated with a quasi-Hermitian Hamiltonian and its physical implications are scrutinised. Consequences of the non-uniqueness such as the question of the probability interpretation and the possible and forbidden choices of…

Quantum Physics · Physics 2007-10-31 H. B. Geyer , W. D. Heiss , F. G. Scholtz

We study the properties of the entanglement spectrum in gapped non-interacting non-Hermitian systems, and its relation to the topological properties of the system Hamiltonian. Two different families of entanglement Hamiltonians can be…

Mesoscale and Nanoscale Physics · Physics 2020-01-06 Loïc Herviou , Nicolas Regnault , Jens H. Bardarson

We study the quantum-mechanical interpretation of models with non-Hermitian Hamiltonians and real spectra. We set up a general framework for the analysis of such systems in terms of Hermitian Hamiltonians defined in the usual Hilbert space…

Quantum Physics · Physics 2007-05-23 R. Kretschmer , L. Szymanowski

Many features of Bloch oscillations in one-dimensional quantum lattices with a static force can be described by quasiclassical considerations for example by means of the acceleration theorem, at least for Hermitian systems. Here the…

Quantum Physics · Physics 2016-06-07 E M Graefe , H J Korsch , A Rush

We present an evaluation of some recent attempts at understanding the role of pseudo-Hermitian and PT-symmetric Hamiltonians in modeling unitary quantum systems and elaborate on a particular physical phenomenon whose discovery originated in…

Quantum Physics · Physics 2015-05-14 Ali Mostafazadeh

Non-Hermitian Hamiltonians possessing a discrete real spectrum motivated a remarkable research activity in quantum physics and new insights have emerged. In this paper we formulate concepts of statistical thermodynamics for systems…

Quantum Physics · Physics 2020-03-18 Natália Bebiano , João da Providência , João P. da Providência

Recently, apparent nonphysical implications of non-Hermitian quantum mechanics (NHQM) have been discussed in the literature. In particular, the apparent violation of the no-signaling theorem, discrimination of nonorthogonal states, and the…

Quantum Physics · Physics 2019-12-25 Chia-Yi Ju , Adam Miranowicz , Guang-Yin Chen , Franco Nori

Non-Hermitian Hamiltonians are relevant to describe the features of a broad class of physical phenomena, ranging from photonics and atomic and molecular systems to nuclear physics and mesoscopic electronic systems. An important question…

Mesoscale and Nanoscale Physics · Physics 2021-04-21 Ygor Pará , Giandomenico Palumbo , Tommaso Macrì

Excited bound states are often understood within scattering based theories as resulting from the collision of a particle on a target via a short-range potential. We show that the resulting formalism is non-Hermitian and describe the Hilbert…

Quantum Physics · Physics 2011-11-09 A. Matzkin

The harmonic oscillator Hamiltonian, when augmented by a non-Hermitian $\cal{PT}$-symmetric part, can be transformed into a Hermitian Hamiltonian. This is achieved by introducing a metric which, in general, renders other observables such as…

Quantum Physics · Physics 2007-05-23 D. P. Musumbu , H. B. Geyer , W. D. Heiss

The quantum metric, a geometric measure of state-space distance, has recently attracted growing attention for capturing anomalous state responses to parameter variations. Especially in non-Hermitian systems, the quantum metric has been…

Quantum Physics · Physics 2026-03-31 Teng Liu , Xiaohang Zhang , Jiawei Zhang , Le Luo

Rarely noted paradoxes and their resolution lead to non-Hermitian behaviors due to boundary terms, even for closed systems and with real potentials. The role played by these non-Hermiticities on quantum mechanical uncertainty relations is…

General Physics · Physics 2021-10-05 K. Moulopoulos

In recent years, non-Hermitian quantum physics has gained a lot in popularity in the quantum optics and condensed matter communities in order to model quantum systems with varying symmetries. In this paper, we identify a non-standard inner…

Quantum Physics · Physics 2022-09-09 Jake Southall , Daniel Hodgson , Robert Purdy , Almut Beige

This paper proposes to broaden the canonical formulation of quantum mechanics. Ordinarily, one imposes the condition $H^\dagger=H$ on the Hamiltonian, where $\dagger$ represents the mathematical operation of complex conjugation and matrix…

Quantum Physics · Physics 2009-10-31 Carl Bender , Stefan Boettcher , Peter Meisinger

Non-hermiticity presents a vast newly opened territory that harbors new physics and applications such as lasing and sensing. However, only non-Hermitian systems with real eigenenergies are stable, and great efforts have been devoted in…

Other Condensed Matter · Physics 2022-10-25 Russell Yang , Jun Wei Tan , Tommy Tai , Jin Ming Koh , Linhu Li , Stefano Longhi , Ching Hua Lee

Quantum sensing utilizing unique quantum properties of non-Hermitian systems to realize ultra-precision measurements has been attracting increasing attention. However, the debate on whether non-Hermitian systems are superior to Hermitian…

Quantum Physics · Physics 2023-12-14 Yan-Yi Wang , Chun-Wang Wu , Wei Wu , Ping-Xing Chen

Interacting and open quantum systems can be formulated in terms of an effective non-Hermitian Hamiltonian (NHH), however, there are important constraints that must be satisfied by the effective action and the associated Green's functions.…

Quantum Physics · Physics 2026-05-22 Aaron Kleger , Rufus Boyack

We show that similarity (or equivalent) transformations enable one to construct non-Hermitian operators with real spectrum. In this way we can also prove and generalize the results obtained by other authors by means of a gauge-like…

Quantum Physics · Physics 2016-08-08 Francisco M. Fernández

The non-Hermiticity of the system gives rise to a distinct knot topology in the complex eigenvalue spectrum, which has no counterpart in Hermitian systems. In contrast, the singular values of a non-Hermitian (NH) Hamiltonian are always real…

Quantum Physics · Physics 2026-04-06 Gaurav Hajong , Ranjan Modak , Bhabani Prasad Mandal