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**Search for:**quantum-thermodynamics

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#### Thermodynamically optimal creation of correlations

, Article Journal of Physics A: Mathematical and Theoretical ; Volume 52, Issue 46 , 2019 ; 17518113 (ISSN) ; Clivaz, F ; Vitagliano, G ; Erker, P ; Rezakhani, A ; Huber, M ; Friis, N ; Sharif University of Technology
Institute of Physics Publishing
2019

Abstract

Correlations lie at the heart of almost all scientific predictions. It is therefore of interest to ask whether there exist general limitations to the amount of correlations that can be created at a finite amount of invested energy. Within quantum thermodynamics such limitations can be derived from first principles. In particular, it can be shown that establishing correlations between initially uncorrelated systems in a thermal background has an energetic cost. This cost, which depends on the system dimension and the details of the energy-level structure, can be bounded from below but whether these bounds are achievable is an open question. Here, we put forward a framework for studying the...

#### A review of quantum thermodynamics

, Article Iranian Journal of Physics Research ; Volume 19, Issue 3 , 2019 , Pages 489-521 ; 16826957 (ISSN) ; Rezakhani, A ; Sharif University of Technology
Isfahan University of Technology
2019

Abstract

In this article, we present a brief and elementary review of quantum thermodynamics and its achievements and challenges. This review includes an introduction to some fundamental concepts such as internal energy, heat, work, entropy, entropy production, thermal equilibrium, second law of quantum thermodynamics, relation between thermodynamics and information theory, as well as a discussion of how quantum effects such as entanglement and correlations affect performance of quantum heat engines. © 2019 by the authors. Licensee MDPI, Basel, Switzerland

#### Dynamical Behavior in Statistical Mechanics of Open Quantum Systems

, M.Sc. Thesis Sharif University of Technology ; Rezakhani, Ali (Supervisor)
Abstract

A fundamental question in investigating decoherence and equilibrium of a system in contact with a bath is how its entropy changes in time. Normally, von Neumann’s entropy is used in such studies to quantize degree of decoherence. Recently, certain researches have been conducted addressing entropy rate and various bounds have been achieved for this quantity, utilizing which one can discuss decoherence rate and equilibrium state of open systems.In this thesis, we introduce these bounds and try to improve them. Using improved bound we will show that for almost all conceivable initial states of the system and the bath, average of entropy rate will be negligible. This result is obtained under...

#### Critical assessment on the minimal work approach in quantum thermodynamics

, Article Physica E: Low-Dimensional Systems and Nanostructures ; Volume 42, Issue 3 , 2010 , Pages 488-490 ; 13869477 (ISSN) ; Shafiee, A ; Sharif University of Technology
Abstract

According to a well-known approach in quantum thermodynamics, the characteristics of a system in a process can be estimated by calculating work in the process. Here, we are going to show that this approach cannot provide with us a clear depiction of the second law of thermodynamics in some specific (but simple) processes

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A Survey on Some Modern Approaches to Quantum Thermodynamics

,
M.Sc. Thesis
Sharif University of Technology
;
Shafiee, Afshin
(Supervisor)
Abstract

The relationship between quantum theory and thermodynamics has gained so much attention in recent years. Thermodynamics is indeed a phenomenological science and its theoretical foundations are not clear as well. In the nineteenth century, Boltzmann tried to establish a connection between concepts of thermodynamics and classical mechanics (as a consistent theoretical domain). With development of quantum mechanics in twentieth century, the possibility of analyzing and formulating of the multi-particle systems based on quantum formalism increased. Quantum approach to thermodynamic phenomena has been studied in various ways. Here basic questions are, e.g. how to define Thermodynamic entities...

#### Review of the Role of Correlation, Interaction, and Information Transmission Speed in Quantum Heat Engines

, M.Sc. Thesis Sharif University of Technology ; Rezakhani, Alireza (Supervisor)
Abstract

The study of thermodynamics of small-scale systems or quantum thermodynamics has been recently receiving a lot of attention from quantum scientists in the field of quantum information. The main purpose of this thesis is to review the effects of quantum phenomena such as correlations, on the laws of thermodynamics and specifically on the efficiency of quantum heat engines. We first review some of the most important topics of classical thermodynamics such as the laws of thermodynamics, thermodynamic potentials and heat engines. The trade-off between power and efficiency for classical heat engines is investigated. It is shown that, this is impossible to have a heat engine performing with the...

#### Thermodynamical Investigation of Quantum Systems

, Ph.D. Dissertation Sharif University of Technology ; Golshani, Mehdi (Supervisor)
Abstract

Investigation of the consistency between physical theories has always resulted in the advancement of physics. Meanwhile, study of the consistency between quantum mechanics and thermodynamics has led to the development of a branch in theoretical physics called quantum thermodynamics. In addition to the consistency problem,employing other features of quantum mechanics such as coherency and entanglement, to enhance thermodynamic processes is another ongoing subject of research. In order to study the thermodynamics of quantum systems, we use the first law of thermodynamics to present a derivation of quantum potential. Quantum potential is a term in the equations of motion of a quantum system of...

#### Relation Between Correlation and Energy in Quantum Thermodynamics

, Ph.D. Dissertation Sharif University of Technology ; Rezakhani, Ali (Supervisor) ; Huber, Marcus (Supervisor) ; Jafari, Akbar (Supervisor)
Abstract

Quantum thermodynamics is a new field of study in physics, which by considering the fundamentals of statistical mechanics, open quantum system, quantum information and mesoscopic system aims at the investigation of quantum systems from a thermodynamical point of view. To achieve these aims, a better understanding of the relations between quantum and thermodynamics fundamentals is essential. Energy and correlation are two key concepts in statistical mechanics and quantum thermodynamics (and information), respectively, that studying the relation between them will shed light on the fundamentals of quantum thermodynamics. As generating any correlation in quantum systems with initial heat state...

#### Generalizing of Quantum Theory to Macro Systems and Thermodynamics

, Ph.D. Dissertation Sharif University of Technology ; Shafiee, Afshin (Supervisor)
Abstract

Up to this day, no conflict ever observed between experiments and the predictions of quantum mechanics. Scientists are in the belief that quantum mechanics is a universal theory and all the systems, even the classical ones, are quantum mechanical in their nature. In this regard, modeling the Earth-Sun dynamics using Hydrogen atom Hamiltonian has been addressed. Since we understand the classical systems with trajectories, we used Bohmian mechanics as an alternative way to study the Earth-Sun dynamics in a quantum fashion. Moreover, for better understanding the concept of the quantum to classical transition, we studied quantum thermodynamics. Accordingly, we described open quantum systems in...

#### Review of Thermalization in Closed Quantum Systems

, M.Sc. Thesis Sharif University of Technology ; Rezakhani, Ali (Supervisor)
Abstract

For a physical system, equilibrium is defined as a state in which the values of macroscopic quantities describing the system do not change in time. We observe systems around us reaching equilibrium every day. Describing such a seemingly simple phenomena has remained as one of the important challenges in theoretical physics. So far, various explanations for thermalization (approach to equilibrium) have been offered within classical and quantum thermodynamics. In classical statistical mechanics, the microcanonical ensemble provides a suitable prediction of the thermal behavior of a closed system. In this ensemble, using ergodic hypothesis and chaos theory one can assume that all microstates...

#### Quench dynamics and zero-energy modes: The case of the Creutz model

, Article Physical Review B ; Volume 99, Issue 5 , 2019 ; 24699950 (ISSN) ; Johannesson, H ; Langari, A ; Martin Delgado, M. A ; Sharif University of Technology
American Physical Society
2019

Abstract

In most lattice models, the closing of a band gap typically occurs at high-symmetry points in the Brillouin zone. Differently, in the Creutz model - describing a system of spinless fermions hopping on a two-leg ladder pierced by a magnetic field - the gap closing at the quantum phase transition between the two topologically nontrivial phases of the model can be moved by tuning the hopping amplitudes. We take advantage of this property to examine the nonequilibrium dynamics of the model after a sudden quench of the magnetic flux through the plaquettes of the ladder. For a quench to one of the equilibrium quantum critical points, we find that the revival period of the Loschmidt echo -...