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The time-evolution operator corresponding to the fractional-time Schr\"odinger equation is nonunitary because it fails to preserve the norm of the vector state in the course of its evolution. However, in the context of the time-dependent…

Quantum Physics · Physics 2025-02-05 Danilo Cius

The Hamiltonian mean-field (HMF) model is a system of fully coupled rotators which exhibits a second-order phase transition at some critical energy in its canonical ensemble. We investigate the case where the interaction between the rotors…

Statistical Mechanics · Physics 2018-05-04 Nivedita Bhadra , Soumen K Patra

We study a class of time-dependent (TD) non-Hermitian Hamiltonians $H(t)$ that can be transformed into a time-independent pseudo-Hermitian Hamiltonian $\mathcal{H}_{0}^{PH}$ using a suitable TD unitary transformation $F(t)$. The latter can…

Quantum Physics · Physics 2025-10-06 F. Kecita , B. Khantoul , A. Bounames

Given a first order dynamical system possessing a commutative algebra of dynamical symmetries, we show that, under certain conditions, there exists a Poisson structure on an open neighbourhood of its regular (not necessarily compact)…

Dynamical Systems · Mathematics 2015-06-26 G. Giachetta , L. Mangiarotti , G. Sardanashvily

I point out that if one defines the operator $U_R(t)$ as done by M. Znojil in his reply [arXiv:0711.0514v1] to my comment [arXiv:0711.0137v1] and also accepts the validity of the defining relation of $U_R(t)$ as given in his paper…

Quantum Physics · Physics 2007-11-08 Ali Mostafazadeh

The dynamics of classical and quantum systems which are driven by a high frequency ($\omega$) field is investigated. For classical systems the motion is separated into a slow part and a fast part. The motion for the slow part is computed…

Chaotic Dynamics · Physics 2009-11-10 Saar Rahav , Ido Gilary , Shmuel Fishman

The time evolution of the KK system as a two-qubit system is given. The effect which is interpreted as CP violation in neutral kaon decays is explained via violation of quantum correlations during time evolution of the KK system as…

Quantum Physics · Physics 2007-05-23 Jaroslav Hruby

This paper examines the features of a generalized position-dependent mass Hamiltonian in a supersymmetric framework in which the constraints of pseudo-Hermiticity and CPT are naturally embedded. Different representations of the charge…

Quantum Physics · Physics 2013-02-27 B. Bagchi , A. Banerjee , A. Ganguly

One of the axioms of quantum field theory is the property of unitarity of the evolution operator. However, if one considers the quantum electrodynamics in the external field in the leading order of perturbation theory, one will find that…

High Energy Physics - Theory · Physics 2008-11-26 O. Yu. Shvedov

We prove under certain assumptions that there exists a solution of the Schrodinger or the Heisenberg equation of motion generated by a linear operator H acting in some complex Hilbert space H, which may be unbounded, not symmetric, or not…

Mathematical Physics · Physics 2015-06-17 Shinichiro Futakuchi , Kouta Usui

Quantum timeless approaches solve the problem of time by recovering the usual unitary evolution of quantum theory relative to a clock in a stationary quantum Universe. For some Hamiltonians of the Universe, such as those including an…

Quantum Physics · Physics 2026-04-14 Simone Rijavec

$\mathcal{PT}$-symmetric quantum mechanics has been considered an important theoretical framework for understanding physical phenomena in $\mathcal{PT}$-symmetric systems, with a number of $\mathcal{PT}$-symmetry related applications. This…

Quantum Physics · Physics 2019-12-25 Da-Jian Zhang , Qing-hai Wang , Jiangbin Gong

In this paper, Part II, of a two part paper we apply the results of [KW], Part I, to establish, with an explicit dual coordinate system, a commutative analogue of the Gelfand-Kirillov theorem for M(n), the algebra of $n\times n$ complex…

Symplectic Geometry · Mathematics 2007-05-23 Bertram Kostant , Nolan Wallach

We propose a new approximation-technique to deal with the exact macroscopic integro-differential evolution equations of statistical systems which self-consistently accounts for dissipative effects. Concentrating on one and two point…

High Energy Physics - Phenomenology · Physics 2007-05-23 Herbert Nachbagauer

We develop a mathematical framework for quantum time transfer based on commuting families of Hamiltonians and synchronization observables. The synchronization subspace is defined as the kernel of a difference operator between local clocks,…

Quantum Physics · Physics 2025-10-09 Nicholas R. Allgood

Transient stability is crucial to the reliable operation of power systems. Existing theories rely on the simplified electromechanical models, substituting the detailed electromagnetic dynamics of inductor and capacitor with their impedance…

Systems and Control · Electrical Eng. & Systems 2025-02-17 Xinyuan Jiang , Constantino M. Lagoa , Yan Li

We present easily verifiable sufficient conditions of time-independence and commutativity for local and nonlocal symmetries for a large class of homogeneous (1+1)-dimensional evolution systems. In contrast with the majority of known…

Exactly Solvable and Integrable Systems · Physics 2007-05-23 A. Sergyeyev

We consider $d$-dimensional quantum systems which for positive times evolve with a time-independent Hamiltonian in a nonequilibrium state that we keep generic in order to account for arbitrary evolution at negative times. We show how the…

Statistical Mechanics · Physics 2024-06-24 Gesualdo Delfino , Marianna Sorba

Although the Hamiltonian in quantum physics has to be a linear operator, it is possible to make quantum systems behave as if their Hamiltonians contained antilinear (i.e., semilinear or conjugate-linear) terms. For any given quantum system,…

Mathematical Physics · Physics 2013-01-03 Michael Eisele

We review the well-known Hellmann Feynman Theorem (HFT), originally developed for Hermitian systems to facilitate the calculation of forces among the molecules. Our work extends this foundational theorem to the domain of non-Hermitian…

Quantum Physics · Physics 2025-04-02 Gaurav Hajong , Bhabani Prasad Mandal