The Study On Quantum Heat Engine And The Related Problems

With the rapid development of quantum information, quantum thermodynamics andquantum optics theories, much more physical phenomena (especially thermodynamic phe-nomenon) have been considered from microscopic perspectives rather than the macroscopic.As a result, the concept of heat engine in classical thermodynamics has also been extendedto the field of quantum mechanics. For quantum heat engine, it is an important model toexplore the thermodynamic properties of quantum systems. Quantum heat engine could be-come an effective way to reveal the physical nature behind some macroscopic thermodynamicphenomenon from microscopic perspective. It plays an important role in promoting the es-tablishment and perfection of quantum thermodynamics. In this paper, using the quantumquantum engine models we will study some related problems in the fields of quantum me-chanics, quantum information and quantum thermodynamics.In the chapter1, we review some thermodynamic problems associated with the Maxwell’sDemon in recent years, and analyze the development and significance of quantum engines.In the chapter2, we mainly introduce some basic concepts and laws, such as the first lawand second law of thermodynamics, Shannon entropy and Von Neumann entropy, quantumcoherence and quantum correlation (including the quantum entanglement and the quantumdiscord) and so on; provide some basic knowledge about classical Szilard engine and cavityquantum electrodynamics (CQED). In the chapter3, we revisit the quantum Szilard enginewith fully quantum consideration. Based on two different cycle strategies, the thermodynamicproperties are analyzed. We find that the amount of work extracted by the system depends onthe microscopic information and the cyclic strategies, and the macroscopic information actslike a feedback controller which has no any contribution to the work. It is the first time todemonstrate the different roles of the microscopic information and the macroscopic informa-tion. At last, thermodynamic behaviors are discussed in the classical limits, i.e., the width ofwell or the temperature of the bath towards infinity. We find that the quantum Szilard engine,in the classical limits, could reduce to the classical Szilard engine. In the chapter4, Based onthe model consisting of single quantum mechanical particle confined to an one-dimensional infinite square well, we construct a nonequilibrium quantum Otto cycle (NQOC). We discussthe thermodynamic properties of the NQOC when the two-level and multi-level systems actas the work substance of the engine, respectively. Compared with the conventional quantumOtto engine investigated by T. D. Kieu, we find that the negentropy produced in the NQOCcan lead to many interesting features:1) the NQOC is capable of extracting more work, soit is more efficient;2) the NQOC could extract work from a single bath;3) in the certainsituation, the NQOC could transfer all the heat absorbed from baths into useful work. Wecompletely demonstrate that the important physical meaning of negentropy which could actas an effective source of efficiency in thermodynamic cycle. At last, we also derive the effi-ciency of NQOC in the classical limit which coincides with the one of classical Otto cycle.In the chapter5, we discuss the effects of multi-particle nonequilibrium reservoir’s quantumcoherence and the quantum correlations on the system’s work capability. With the analyticand numerical simulation methods, we demonstrate quantum coherence rather than quantumcorrelation of reservoir acting as the resource of system’s work capability clearly. At last, wesummarize this paper and point out the direction for future researches in the six chapter.