Thermodynamics was developed in the XIXth century to provide a physical description to engines and other macroscopic thermal machines. Since then, progress in nanotechnologies urged to extend these formalism, initially designed for classical systems, to the quantum world. During this thesis, I have built a formalism to study the stochastic thermodynamics of quantum systems, in which quantum measurement plays a central role : like the thermal reservoir of standard stochastic thermodynamics, it is the primary source of randomness in the system's dynamics. I first studied projective measurement as a thermodynamic process. I evidenced that measurement is responsible for an uncontroled variation of the system's energy that I called quantum heat, and also a production of entropy. As a proof of concept, I studied an engine extracting work from the measurementinduced quantum fluctuations. Then, I extended this formalism to generalized measurements, which allowed to describe open quantum systems (i.e. in contact with reservoirs). I defined work, heat and entropy production for single realizations of thermodynamic protocols, and retrieved that these quantities obey fluctuation theorems. I applied this formalism to the canonical situation of quantum optics, i.e. a Qubit coupled to a laser and a the vacuum. Finally, I studied a promising platform to test Qubit's thermodynamics: a hybrid optomechanical system. The formalism developed in this thesis is of interest for the quantum thermodynamics community as it enables to characterize quantum heat engines and compare their performances to their classical analogs. Furthermore, as it sets quantum measurement as a thermodynamic process, it pave the ways to a new kind of thermodynamic machines, exploiting the specificities of quantum realm in an unprecedented way.
High-order interactions in quantum optomechanics: fluctuations, dynamics and thermodynamics
Institute for Quantum Computing Analytics (PGI-12), Forschungszentrum Jülich（于利希研究中心量子计算分析研究所（PGI-12））；Dipartimento di Fisica, Università di Pavia（帕维亚大学物理系）；Department of Information and Communication Engineering, Graduate School of Information Science and Technology, The University of Tokyo（东京大学信息理工学研究科信息通信工程学专攻）；Theoretical Physics, Universität des Saarlandes（萨尔兰州立大学理论物理系）
