  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.
