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In recent reports, suggestions have been put forward to the effect that parity and time-reversal (PT) symmetry in quantum mechanics is incompatible with causality. It is shown here, in contrast, that PT-symmetric quantum mechanics is fully…

Quantum Physics · Physics 2016-04-07 Dorje C. Brody

An elucidation of the current state of art in quasi-Hermitian quantum theory (QHQT) as inspired by the recent paper by Alase et al (J. Phys. A: Math. Theor. 55 (2022) 244003, paper [1]) is offered. We point out that the author's main…

Quantum Physics · Physics 2023-02-01 Miloslav Znojil

Non-Hermitian PT-symmetric quantum-mechanical Hamiltonians generally exhibit a phase transition that separates two parametric regions, (i) a region of unbroken PT symmetry in which the eigenvalues are all real, and (ii) a region of broken…

Quantum Physics · Physics 2012-10-11 Carl M. Bender , David J. Weir

A re-formulated, non-Hermitian version of the Witten's supersymmetric quantum mechanics is presented. Its use of pseudo-Hermitian (so called PT symmetric) Hamiltonians is reviewed and illustrated via several forms of an innovated…

High Energy Physics - Theory · Physics 2007-05-23 Miloslav Znojil

PT-symmetric quantum theory was originally proposed with the aim of extending standard quantum theory by relaxing the Hermiticity constraint on Hamiltonians. However, no such extension has been formulated that consistently describes states,…

Quantum Physics · Physics 2022-05-26 Abhijeet Alase , Salini Karuvade , Carlo Maria Scandolo

For a subclass of a general $\mathcal{PT}-$symmetric Hamiltonian obeying anti-commutation relation with its conjugate, a Hermitian basis is found that spans the bi-orthonormal energy eigenvectors. Using the modified projectors constructed…

Quantum Physics · Physics 2025-12-04 Baibhab Bose , Devvrat Tiwari , Subhashish Banerjee

Most recently it has been observed e.g. by Bender and Klevansky (arXiv:0905.4673 [hep-th]) that the C-operator related to a PT-symmetric non-Hermitian Hamilton operator is not unique. Moreover it has been remarked by Shi and Sun…

High Energy Physics - Theory · Physics 2009-06-09 F. Kleefeld

We extend the definition of generalized parity $P$, charge-conjugation $C$ and time-reversal $T$ operators to nondiagonalizable pseudo-Hermitian Hamiltonians, and we use these generalized operators to describe the full set of symmetries of…

Quantum Physics · Physics 2009-11-10 A. Blasi , G. Scolarici , L. Solombrino

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

Emphasizing the physical constraints on the formulation of a quantum theory based on the standard measurement axiom and the Schroedinger equation, we comment on some conceptual issues arising in the formulation of PT-symmetric quantum…

Quantum Physics · Physics 2009-11-13 Ali Mostafazadeh

A discrete $N-$point Runge-Kutta version $H^{(N)}({\lambda})$ of one of the simplest non-Hermitian square-well Hamiltonians with real spectrum is studied. A complete set of its possible hermitizations (i.e., of the eligible metrics…

Mathematical Physics · Physics 2010-01-04 Miloslav Znojil

A defining quantity of a physical system is its energy which is represented by the Hamiltonian. In closed quantum mechanical or/and coherent wave-based systems the Hamiltonian is introduced as a Hermitian operator which ensures real energy…

Mesoscale and Nanoscale Physics · Physics 2026-01-05 Jamal Berakdar , Xi-guang Wang

It has recently been shown that a non-Hermitian Hamiltonian H possessing an unbroken PT symmetry (i) has a real spectrum that is bounded below, and (ii) defines a unitary theory of quantum mechanics with positive norm. The proof of…

High Energy Physics - Theory · Physics 2014-11-18 Carl M. Bender , Dorje C. Brody , Hugh F. Jones

Non-Hermitian systems satisfying parity-time (PT) symmetry have aroused considerable interest owing to their exotic features. Anti-PT symmetry is an important counterpart of the PT symmetry, and has been studied in various classical…

Quantum Physics · Physics 2024-06-21 Ji Bian , Pengfei Lu , Teng Liu , Hao Wu , Xinxin Rao , Kunxu Wang , Qifeng Lao , Yang Liu , Feng Zhu , Le Luo

The Hamiltonian for quantum electrodynamics becomes non-Hermitian if the unrenormalized electric charge $e$ is taken to be imaginary. However, if one also specifies that the potential $A^\mu$ in such a theory transforms as a pseudovector…

High Energy Physics - Theory · Physics 2011-07-19 Carl M. Bender , Ines Cavero-Pelaez , Kimball A. Milton , K. V. Shajesh

Manifestly non-Hermitian quantum graphs with real spectra are introduced and shown tractable as a new class of phenomenological models with several appealing descriptive properties. For illustrative purposes, just equilateral star-graphs…

High Energy Physics - Theory · Physics 2009-11-10 Miloslav Znojil

A Su-Schrieffer-Heeger model with added PT-symmetric boundary term is studied in the framework of pseudo-hermitian quantum mechanics. For two special cases, a complete set of pseudometrics is constructed in closed form. When complemented…

Mathematical Physics · Physics 2016-04-05 Frantisek Ruzicka

In an amended version of non-Hermitian interaction picture we propose to work with the states $\psi(t)$ in a dyadic representation. The control of evolution via two conjugate Schr\"{o}diner equations then renders the usual necessity of the…

Quantum Physics · Physics 2023-06-29 Miloslav Znojil

In this paper a quantum mechanics is built by means of a non-Hermitian momentum operator. We have shown that it is possible to construct two Hermitian and two non-Hermitian type of Hamiltonians using this momentum operator. We can construct…

Mathematical Physics · Physics 2011-03-25 Juan M. Romero , O. Gonzalez-Gaxiola , J. Ruiz de Chavez , R. Bernal-Jaquez

A given Hamiltonian matrix H with real spectrum is assumed tridiagonal and non-Hermitian. Its possible Hermitizations via an amended, ad hoc inner-product metric are studied. Under certain reasonable assumptions, all of these metrics are…

Mathematical Physics · Physics 2012-02-10 Miloslav Znojil