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The quantum effective action may be used to invert information from phenomena, either measured or ideal, to the microscopic Lagrangian. As an example of this procedure the lattice composition of a solid can be determined in principle from…

General Physics · Physics 2007-05-23 Gordon Chalmers

We investigate the quantum field aspects in flat spacetime for an uniformly accelerated observer moving in a thermal bath. In particular, we obtain an exact closed expression of the reduced density matrix for an uniformly accelerated…

General Relativity and Quantum Cosmology · Physics 2014-02-26 Sanved Kolekar

We study the structure of the time evolution of the density matrix in contact with a thermal bath in a standard projection operator sheme. The reduced density matrix of the system in the steady state is obtained by tracing out the degree of…

Statistical Mechanics · Physics 2009-05-04 Takashi Mori , Seiji Miyashita

Inspired by path integral molecular dynamics, we build a spin model, in terms of spin coherent states, from which we can compute the quantum expectation values of a spin in a constant magnetic field, at finite temperature. This formulation…

Materials Science · Physics 2023-11-02 Thomas Nussle , Stam Nicolis , Joseph Barker

We address the problem of quantum chaos: Is there a rigorous, physically meaningful definition of chaos in quantum physics? Can the tools of classical chaos theory, like Lyapunov exponents, Poincar\'e sections etc. be carried over to…

Quantum Physics · Physics 2016-08-16 L. A. Caron , H. Jirari , H. Kröger , X. Q. Luo , G. Melkonyan , K. J. M. Moriarty

We present an effective potential that allows quantum thermal expectation values of a position-dependent observable to be estimated as a classical ensemble average of the corresponding function. We follow the approach of Feynman and Hibbs,…

Quantum Physics · Physics 2026-02-16 Vijay Ganesh Sadhasivam , Stuart C. Althorpe , Venkat Kapil

The methods of quantum field theory are widely used in condensed matter physics. In particular, the concept of an effective action was proven useful when studying low temperature and long distance behavior of condensed matter systems. Often…

Strongly Correlated Electrons · Physics 2017-08-25 Alexander G. Abanov

A generalization of the thermodynamic uncertainty relations is proposed. It is done by introducing of an additional term proportional to the interior energy into the standard thermodynamic uncertainty relation that leads to existence of the…

High Energy Physics - Theory · Physics 2009-11-10 A. E. Shalyt-Margolin , A. Ya. Tregubovich

We apply reduced density-matrix functional theory to the parabolically confined quantum Hall droplet in the spin-frozen strong magnetic field regime. One-body reduced density matrix functional method performs remarkably well in obtaining…

Mesoscale and Nanoscale Physics · Physics 2015-05-14 E. Tölö , A. Harju

The asymptotic behavior of the integrated density of states for a randomly perturbed lattice at the infimum of the spectrum is investigated. The leading term is determined when the decay of the single site potential is slow. The leading…

Probability · Mathematics 2010-12-14 Ryoki Fukushima , Naomasa Ueki

We present a theory of quantum work statistics in generic chaotic, disordered Fermi liquid systems within a driven random matrix formalism. By extending P. W. Anderson's orthogonality determinant formula to compute quantum work…

Mesoscale and Nanoscale Physics · Physics 2023-03-16 András Grabarits , Márton Kormos , Izabella Lovas , Gergely Zaránd

In this paper, we study the statistical mechanics within the polymer quantization framework in the semiclassical regime. We apply a non-canonical transformation to the phase space variables. Then, we use this non-canonical transformation to…

General Relativity and Quantum Cosmology · Physics 2025-11-24 Kourosh Nozari , Hamed Ramezani

Classical and quantum anharmonic noncommutative oscillators with quartic self-interacting potential are considered and the effect of self-interaction term on the free energy and partition function of both models is calculated to first order…

High Energy Physics - Theory · Physics 2016-04-29 H. Sarvari Karaj-Abad , A. Jahan

Understanding the thermodynamic properties of quantum systems is essential for developing energy-efficient quantum technologies. In this regard, this work explores the application of quantum computational methods to study the quantum…

Quantum Physics · Physics 2025-05-20 Lucas Galvão , Ana Clara das Neves , Maron Anka , Clebson Cruz

The minimal memory required to model a given stochastic process - known as the statistical complexity - is a widely adopted quantifier of structure in complexity science. Here, we ask if quantum mechanics can fundamentally change the…

Quantum Physics · Physics 2017-08-28 Whei Yeap Suen , Jayne Thompson , Andrew J. P. Garner , Vlatko Vedral , Mile Gu

Improving perturbation theory via a variational optimization has generally produced in higher orders an embarrassingly large set of solutions, most of them unphysical (complex). We introduce an extension of the optimized perturbation method…

Soft Condensed Matter · Physics 2009-11-10 J. -L. Kneur , A. Neveu , M. B. Pinto

We propose a method to obtain the thermal-equilibrium density matrix of a many-body quantum system using artificial neural networks. The variational function of the many-body density matrix is represented by a convolutional neural network…

Disordered Systems and Neural Networks · Physics 2020-03-18 Naoki Irikura , Hiroki Saito

We present for the first time time-dependent density-matrix renormalization-group simulations (t-DMRG) at finite temperatures. It is demonstrated how a combination of finite-temperature t-DMRG and time-series prediction allows for an easy…

Strongly Correlated Electrons · Physics 2009-07-28 Thomas Barthel , Ulrich Schollwöck , Steven R. White

We construct a rigourous model of quantum measurement. A two-state model of a negative temperature amplifier, such as a laser, is taken to a classical thermodynamic limit. In the limit, it becomes a classical measurement apparatus obeying…

Quantum Physics · Physics 2007-05-23 Joseph F. Johnson

The ring configurations for classical two-dimensional atoms are calculated within the Thomson model and compared with the results from `exact' numerical simulations. The influence of the functional form of the confinement potential and the…

Condensed Matter · Physics 2009-10-28 B. Partoens , F. M. Peeters