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We study a quantum thermal engine model for which the heat transfer law is determined by Einstein's theory of radiation. The working substance of the quantum engine is assumed to be a two-level quantum systems of which the constituent…

Statistical Mechanics · Physics 2012-11-30 H. Yan , Hao Guo

Recently, Zhang {\em et al.} [PRA, {\bf 75}, 062102 (2007)] extended Kieu's interesting work on the quantum Otto engine [PRL, {\bf 93}, 140403 (2004)] by considering as working substance a bipartite quantum system $AB$ composed of…

Quantum Physics · Physics 2007-08-21 Ye Yeo , Chang Chi Kwong

This paper presents a novel theoretical model to simulate the Unruh temperature by relating it to the critical temperature of multiple Bose-Einstein thermal baths. These thermal baths are conceptualized as snapshots of a Bose-Firework…

The purpose of this short note is to prove a convenient version of It\^o's formula for the Rearranged Stochastic Heat Equation (RSHE) introduced by the two authors in a previous contribution. This equation is a penalised version of the…

Probability · Mathematics 2024-06-11 François Delarue , William R. P. Hammersley

The Bethe-Heitler formula describes bremsstrahlung and it's a typical and important example in quantum electromagnetic dynamics (QED). This formula is widely applied in many branches of physics and astrophysics. We find that the integrated…

High Energy Physics - Phenomenology · Physics 2020-02-26 Wei Zhu

The correlation matrices or tensors in the Bloch representation of density matrices are encoded with entanglement properties. In this paper, based on the Bloch representation of density matrices, we give some new separability criteria for…

Quantum Physics · Physics 2016-08-09 Shu-Qian Shen , Juan Yu , Ming Li , Shao-Ming Fei

The partition function and specific heat of a system consisting of a finite number of bosons confined in an external potential are calculated in canonical ensemble. Using the grand partition function as the generating function of the…

Condensed Matter · Physics 2009-10-30 Wenji Deng , P. M. Hui

A new method is proposed for the calculation of full density matrix and thermodynamic functions of a many-boson system. Explicit expressions are obtained in the pair correlations approximation for an arbitrary temperature. The theory is…

Quantum Physics · Physics 2007-05-23 I. O. Vakarchuk

The Lifshitz formula is well known as a theoretical approach to investigate the Casimir effect at finite temperature. In this Letter, we generalize the Lifshitz formula to the Casimir effect originating from quantum fields at finite…

Quantum Physics · Physics 2025-10-01 Daisuke Fujii , Katsumasa Nakayama , Kei Suzuki

The quantum master equation is introduced for the density matrix representing Bogoliubov-BCS quasiparticles. A constraint to relate the loss and gain factors is taken into account to preserve the form of the density matrix. Such an equation…

Superconductivity · Physics 2014-04-07 Chun-Feng Huang , Keh-Ning Huang

A detailed account of the Kohn-Sham algorithm from quantum chemistry, formulated rigorously in the very general setting of convex analysis on Banach spaces, is given here. Starting from a Levy-Lieb-type functional, its convex and lower…

The Bogoliubov - de Gennes equations are solved for the Coulomb Bose gas describing a fluid of charged bosons at finite temperature. The approach is applicable in the weak coupling regime and the extent of its quantitative usefulness is…

Condensed Matter · Physics 2009-10-31 E. Strepparola , A. Minguzzi , M. P. Tosi

Using a formalism based on the two-body S-matrix we study two-dimensional Bose and Fermi gases with both attractive and repulsive interactions. Approximate analytic expressions, valid at weak coupling and beyond, are developed and applied…

Quantum Gases · Physics 2017-07-18 Guilherme Franca , Andre LeClair , Joshua Squires

Established heat engines in quantum regime can be modeled with various quantum systems as working substances. For example, in the non-relativistic case, we can model the heat engine using infinite potential well as a working substance to…

Quantum Physics · Physics 2020-06-09 Pritam Chattopadhyay , Goutam Paul

We derive quantum Boltzmann equations for preheating by means of the density matrix formalism, which account for both the non-adiabatic particle production and the leading collisional processes between the produced particles. In so doing,…

High Energy Physics - Theory · Physics 2018-10-01 William T. Emond , Peter Millington , Paul M. Saffin

We study the spontaneous formation of defects in the order parameter of a trapped ultracold bosonic gas while crossing the critical temperature for Bose-Einstein Condensation (BEC) at different rates. The system has the shape of an…

This is a book about Lieb's Simplified approach to the Bose gas, which is a family of effective single-particle equations to study the ground state of many-body systems of interacting Bosons. It was introduced by Lieb in 1963, and recently…

Mathematical Physics · Physics 2025-02-10 Ian Jauslin

We study quench dynamics of the Bose-Hubbard model by exact diagonalization. Initially the system is at thermal equilibrium and of a finite temperature. The system is then quenched by changing the on-site interaction strength $U$ suddenly.…

Statistical Mechanics · Physics 2011-06-21 J. M. Zhang , C. Shen , W. M. Liu

We have computed the one--body density matrix rho_1 in solid 4He at T=0 K using the Shadow Wave Function (SWF) variational technique. The accuracy of the SWF has been tested with an exact projector method. We find that off-diagonal long…

Statistical Mechanics · Physics 2009-11-11 D. E. Galli , M. Rossi , L. Reatto

Based on a generalization of Hohenberg-Kohn's theorem, we propose a ground state theory for bosonic quantum systems. Since it involves the one-particle reduced density matrix $\gamma$ as a natural variable but still recovers quantum…