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In quantum thermodynamics, a system is described by a Hamiltonian and a list of non-commuting charges representing conserved quantities like particle number or electric charge, and an important goal is to determine the system's minimum…

Quantum Physics · Physics 2025-05-19 Nana Liu , Michele Minervini , Dhrumil Patel , Mark M. Wilde

In this paper we are discussing the question how a continuous quantum system can be simulated by mean field fluctuations of a finite number of qubits. On the kinematical side this leads to a convergence result which states that…

Quantum Physics · Physics 2016-01-20 Zoltan Kadar , Michael Keyl , Geza Toth , Zoltan Zimboras

We examine the fundamental aspects of statistical mechanics, dividing the problem into a discussion purely about probability, which we analyse from a Bayesian standpoint. We argue that the existence of a unique maximising probability…

Statistical Mechanics · Physics 2015-12-07 B. Buck , A. C. Merchant

We consider ontological models of a quantum system, assuming that not all probability distributions over the space $\Lambda$ of ontic states are preparable, only those belonging to a certain set C. We assume further that every POVM with a…

Quantum Physics · Physics 2022-05-10 Roderich Tumulka

We derive quantum nonequilibrium equalities in absolutely irreversible processes. Here by absolute irreversibility we mean that in the backward process the density matrix does not return to the subspace spanned by those eigenvectors that…

Statistical Mechanics · Physics 2015-07-14 Ken Funo , Yûto Murashita , Masahito Ueda

The response of a quantum system in a pure state to an external force is investigated by reconsidering the standard statistical approach to quantum dynamics on the light of the statistical description of equilibrium based on typicality. We…

Statistical Mechanics · Physics 2011-04-26 Barbara Fresch , Giorgio J. Moro

It is proposed to give up the description of physical states in terms of ensembles of state vectors with various probabilities, relying instead solely on the density matrix as the description of reality. With this definition of a physical…

Quantum Physics · Physics 2015-06-19 Steven Weinberg

We ask to what extent an isolated quantum system can eventually "contract" to be contained within a given Hilbert subspace. We do this by starting with an initial random state, considering the probability that all the particles will be…

General Relativity and Quantum Cosmology · Physics 2020-05-14 Joshua M. Deutsch , Dominik Šafránek , Anthony Aguirre

We consider possible tests of the Einstein Equivalence Principle for physical systems in which quantum-mechanical vacuum energies cannot be neglected. Specific tests include a search for the manifestation of non-metric effects in Lamb-shift…

General Relativity and Quantum Cosmology · Physics 2015-06-25 C. Alvarez , R. B. Mann

Quantum resource theories provide a mathematically rigorous way of understanding the nature of various quantum resources. An important problem in any quantum resource theory is to determine how quantum states can be converted into each…

Quantum Physics · Physics 2025-12-09 Tulja Varun Kondra , Chandan Datta , Alexander Streltsov

In a quantum system, different energy eigenstates have different properties or features, allowing us define a classifier to divide them into different groups. We find that the ratio of each type of energy eigenstates in an energy shell…

Quantum Physics · Physics 2023-03-29 Zhelun Zhang , Zhenduo Wang , Biao Wu

Non-commutative propositions are characteristic of both quantum and non-quantum (sociological, biological, psychological) situations. In a Hilbert space model states, understood as correlations between all the possible propositions, are…

Quantum Physics · Physics 2009-11-07 D. Aerts , M. Czachor , L. Gabora , M. Kuna , A. Posiewnik , J. Pykacz , M. Syty

The thermodynamical properties of a generalized Dicke model are calculated and related with the critical properties of its energy spectrum, namely the quantum phase transitions (QPT) and excited state quantum phase transitions (ESQPT). The…

Quantum Physics · Physics 2016-10-12 Miguel A. Bastarrachea-Magnani , Sergio Lerma-Hernández , Jorge G. Hirsch

For a macroscopic, isolated quantum system in an unknown pure state, the expectation value of any given observable is shown to hardly deviate from the ensemble average with extremely high probability under generic equilibrium and…

Statistical Mechanics · Physics 2007-10-24 Peter Reimann

We present some basic inequalities between the classical and quantum values of free energy, entropy and mean energy. We investigate the transition from the deterministic case (classical mechanics) to the probabilistic case (quantum…

Mathematical Physics · Physics 2022-07-12 Lev Sakhnovich

The maximum entropy principle, as applied to quantum systems, is a fundamental prescript positing that for a quantum system for which we only have partial knowledge, the maximum entropy state consistent with the partial knowledge is a…

Quantum Physics · Physics 2025-07-24 Siddhartha Das , Ujjwal Sen

We revisit the relationship between quantum separability and the sign of the relative q-entropies of composite quantum systems. The q-entropies depend on the density matrix eigenvalues p_i through the quantity omega_q = sum_i p_i^q. Renyi's…

Quantum Physics · Physics 2016-09-08 J. Batle , A. R. Plastino , M. Casas , A. Plastino

We explore a recently introduced quantum thermodynamic entropy $S^Q_{univ}$ of a pure state of a composite system-environment computational "universe" with a simple system $\mathcal{S}$ coupled to a constant temperature bath $\mathcal{E}$.…

Quantum Physics · Physics 2022-11-28 Phillip C. Lotshaw , Michael E. Kellman

Relaxation dynamics of complex quantum systems with strong interactions towards the steady state is a fundamental problem in statistical mechanics. The steady state of subsystems weakly interacting with their environment is described by the…

Statistical Mechanics · Physics 2016-06-22 Alexey M. Shakirov , Yulia E. Shchadilova , Alexey N. Rubtsov

The incomplete nonextensive statistics in the canonical and microcanonical ensembles is explored in the general case and in a particular case for the ideal gas. By exact analytical results for the ideal gas it is shown that taking the…

Statistical Mechanics · Physics 2011-01-17 A. S. Parvan , T. S. Biro