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We show that constraints imposed by strong Hilbert space fragmentation (HSF) along with the presence of certain global symmetries can ensure the reality of eigenspectra of non-Hermitian quantum systems; such a reality cannot be guaranteed…

Strongly Correlated Electrons · Physics 2024-07-16 Somsubhra Ghosh , K. Sengupta , Indranil Paul

We discuss the problem of constructing self-adjoint and lower bounded Hamiltonians for a system of $n>2$ non-relativistic quantum particles in dimension three with contact (or zero-range or $\delta$) interactions. Such interactions are…

Mathematical Physics · Physics 2025-09-23 Daniele Ferretti , Alessandro Teta

The balance of gain and loss in an open system may maintain certain Hermitian dynamical behaviors, which can be hardly observed in a popular Hermitian system. In this paper, we systematically study a 1D PT -symmetry non-Hermitian SSH model…

Quantum Physics · Physics 2018-08-24 K. L. Zhang , P. Wang , G. Zhang , Z. Song

We study the family of Hamiltonians which corresponds to the adjacency operators on a percolation graph. We characterise the set of energies which are almost surely eigenvalues with finitely supported eigenfunctions. This set of energies is…

Mathematical Physics · Physics 2016-01-07 Ivan Veselic'

Shannon-R\'enyi entropies and associated participation spectra quantify how much a many-body wave-function is localized in a given configuration basis. Using these tools, we present an analysis of the ground-state wave functions of various…

Strongly Correlated Electrons · Physics 2014-08-26 David J. Luitz , Nicolas Laflorencie , Fabien Alet

The spectral statistics and entanglement within the eigenstates of generic spin chain Hamiltonians are analysed. A class of random matrix ensembles is defined which include the most general nearest-neighbour qubit chain Hamiltonians. For…

Quantum Physics · Physics 2014-10-08 Huw J Wells

We develop an algebraic approach for finding the eigenfunctions of a large class of few and many-body Hamiltonians, in one and higher dimensions, having linear spectra. The method presented enables one to exactly map these interacting…

Condensed Matter · Physics 2007-05-23 N. Gurappa , Prasanta K. Panigrahi , T. Soloman Raju

The fabrication, utilisation, and efficiency of quantum technologies rely on a good understanding of quantum thermodynamic properties. Many-body systems are often used as hardware for these quantum devices, but interactions between…

Strongly Correlated Electrons · Physics 2022-04-26 Krissia Zawadzki , Amy Skelt , Irene D'Amico

Non-Hermitian many-body systems can be spectrally unstable, so small perturbations may induce large eigenvalue shifts. The pseudospectrum quantifies this instability and provides a perturbation-robust diagnostic. For inverse-polynomially…

Quantum Physics · Physics 2026-03-18 Gengzhi Yang , Jiaqi Leng , Xiaodi Wu , Lin Lin

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

Hamiltonian tridiagonal matrices characterized by multi-fractal spectral measures in the family of Iterated Function Systems can be constructed by a recursive technique here described. We prove that these Hamiltonians are almost-periodic.…

Mesoscale and Nanoscale Physics · Physics 2016-08-31 Giorgio Mantica

Statistical mechanics is founded on the assumption that a system can reach thermal equilibrium, regardless of the starting state. Interactions between particles facilitate thermalization, but, can interacting systems always equilibrate…

In this article, we review the general quantum mechanical setting associated to a non self-adjoint Hamiltonian with real spectrum. Spectral properties of the Hamiltonian of a simple model of the Swanson type are investigated. The…

Quantum Physics · Physics 2019-01-30 N. Bebiano , J. da Providência

We describe the implications of permutation symmetry for the state space and dynamics of quantum mechanical systems of matrices of general size $N$. We solve the general 11- parameter permutation invariant quantum matrix harmonic oscillator…

High Energy Physics - Theory · Physics 2022-12-14 George Barnes , Adrian Padellaro , Sanjaye Ramgoolam

The ultimate precision of any measurement of the temperature of a quantum system is the inverse of the local quantum thermal susceptibility [De Pasquale et al., Nature Communications 7, 12782 (2016)] of the subsystem with whom the…

Quantum Physics · Physics 2017-05-24 Giacomo De Palma , Antonella De Pasquale , Vittorio Giovannetti

Entanglement is a distinguishing feature of quantum many-body systems, and uncovering the entanglement structure for large particle numbers in quantum simulation experiments is a fundamental challenge in quantum information science. Here we…

We show how local bounded interactions in an unbounded Hamiltonian lead to eigenfunctions with favorable low-rank properties. To this end, we utilize ideas from quantum entanglement of multi-particle spin systems. We begin by analyzing the…

Functional Analysis · Mathematics 2022-01-12 Mazen Ali

We consider the Hamiltonian of a system of three quantum mechanical particles on the three-dimensional lattice $\Z^3$ interacting via short-range pair potentials. We prove for the two-particle energy operator $h(k),$ $k\in \T^3$ the…

Spectral Theory · Mathematics 2007-05-23 Sergio Albeverio , Saidakhmat N. Lakaev , Axmad M. Xalxo'jaev

We determine the essential spectrum of Hamiltonians with N-body type interactions that have radial limits at infinity. This extends the HVZ-theorem, which treats perturbations of the Laplacian by potentials that tend to zero at infinity.…

Spectral Theory · Mathematics 2016-08-09 Vladimir Georgescu , Victor Nistor

Topological phases are characterized by their entanglement properties, which is manifest in a direct relation between entanglement spectra and edge states discovered by Li and Haldane. We propose to leverage the power of synthetic quantum…

Quantum Gases · Physics 2022-05-04 Torsten V. Zache , Christian Kokail , Bhuvanesh Sundar , Peter Zoller