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We consider some issues of the representation in the Hamiltonian form of two problems of nonholonomic mechanics, namely, the Chaplygin's ball problem and the Veselova problem. We show that these systems can be written as generalized…

Exactly Solvable and Integrable Systems · Physics 2009-09-29 A. V. Borisov , I. S. Mamaev

A generalized non-Hermitian oscillator Hamiltonian is proposed that consists of additional linear terms which break PT-symmetry explicitly. The model is put into an equivalent Hermitian form by means of a similarity transformation and the…

Quantum Physics · Physics 2008-07-24 Bijan Bagchi , Toshiaki Tanaka

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

We consider the algebra of massive fermions restricted to a diamond in two-dimensional Minkowski spacetime, and in the Minkowski vacuum state. While the massless modular Hamiltonian is known for this setting, the derivation of the massive…

High Energy Physics - Theory · Physics 2024-12-17 Daniela Cadamuro , Markus B. Fröb , Christoph Minz

We generalize the Milne quantization condition to non-Hermitian systems. In the general case the underlying nonlinear Ermakov-Milne-Pinney equation needs to be replaced by a nonlinear integral differential equation. However, when the system…

Quantum Physics · Physics 2015-09-16 Sanjib Dey , Andreas Fring , Laure Gouba

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

We provide a reviewlike introduction into the quantum mechanical formalism related to non-Hermitian Hamiltonian systems with real eigenvalues. Starting with the time-independent framework we explain how to determine an appropriate domain of…

Quantum Physics · Physics 2015-06-26 Carla Figueira de Morisson Faria , Andreas Fring

Despite acute interest in the dynamics of non-Hermitian systems, there is a lack of consensus in the mathematical formulation of non-Hermitian quantum mechanics in the community. Different methodologies are used in the literature to study…

Quantum Physics · Physics 2025-03-31 Karin Sim , Nicolò Defenu , Paolo Molignini , R. Chitra

We consider QM with non-Hermitian quasi-diagonalizable Hamiltonians, i.e. the Hamiltonians having a number of Jordan cells in particular biorthogonal bases. The "self-orthogonality" phenomenon is clarified in terms of a correct spectral…

Quantum Physics · Physics 2016-09-08 A. V. Sokolov , A. A. Andrianov , F. Cannata

A straightforward method to compute Hamilton's density for theories that are linear in the spacetime curvature is provided. It is shown that the lapse function and shift vector still give rise to primary constraints, while the induced…

General Relativity and Quantum Cosmology · Physics 2022-06-23 Yuri Bonder

We introduce the notion of pseudo-Hermiticity and show that every Hamiltonian with a real spectrum is pseudo-Hermitian. We point out that all the PT-symmetric non-Hermitian Hamiltonians studied in the literature belong to the class of…

Mathematical Physics · Physics 2016-09-07 Ali Mostafazadeh

We argue that the correlation between the modular Hamiltonians of two causal diamonds related by a finite time translation is equal to the uncertainty in the modular Hamiltonian of the diamond in their overlap. In a separate section we…

High Energy Physics - Theory · Physics 2023-12-01 T. Banks , W. Fischler

We study the perturbation of the effective Hamiltonian constraint with holonomy correction from Euclidean loop quantum gravity. The Poisson bracket between the corrected Hamiltonian constraint and the diffeomorphism constraint is derived…

General Relativity and Quantum Cosmology · Physics 2013-02-12 Jian-Pin Wu , Yongge Ma

It is shown that the variance of a perturbation Hamiltonian density vanishes in the infinite-volume limit of the perturbed spin systems with quenched disorder. This is proven in a simpler way and under less assumptions than before. A…

Mathematical Physics · Physics 2020-07-28 C. Itoi

Black hole entropy appears to be ``universal''--many independent calculations, involving models with very different microscopic degrees of freedom, all yield the same density of states. I discuss the proposal that this universality comes…

General Relativity and Quantum Cosmology · Physics 2010-04-28 S. Carlip

In this paper we study the contribution of monopole bubbling to the expectation value of supersymmetric 't Hooft defects in Lagrangian theories of class $\mathcal{S}$ on $\mathbb{R}^3\times S^1$. This can be understood as the Witten index…

High Energy Physics - Theory · Physics 2020-01-08 T. Daniel Brennan , Anindya Dey , Gregory W. Moore

Parity-time (PT) symmetric non-Hermitian Hamiltonians bring about many novel features and interesting applications such as quantum gates faster than those in Hermitian systems, and topological state transfer. The performance of evolutions…

Quantum Physics · Physics 2022-07-20 Ji Bian , Kunxu Wang , Pengfei Lu , Xinxin Rao , Hao Wu , Qifeng Lao , Teng Liu , Yang Liu , Feng Zhu , Le Luo

In recent decades, an important shift has taken place with the growing role of non-Hermitian quantum mechanics. What makes this framework remarkable is that the eigenvalues of the Hamiltonians involved can still be real, just as in the…

Quantum Physics · Physics 2025-09-30 Maamache Mustapha

We formulate a systematic algorithm for constructing a whole class of Hermitian position-dependent-mass Hamiltonians which, to lowest order of perturbation theory, allow a description in terms of PT-symmetric Hamiltonians. The method is…

Quantum Physics · Physics 2009-11-11 B. Bagchi , C. Quesne , R. Roychoudhury

Symplectic ensemble of disordered non-Hermitian Hamiltonians is studied. Starting from a model with an imaginary magnetic field, we derive a proper supermatrix $\sigma $-model. The zero-dimensional version of this model corresponds to a…

Disordered Systems and Neural Networks · Physics 2009-10-31 A. V. Kolesnikov , K. B. Efetov