# INTERNSHIP: Quantum stochastic thermodynamics of light

**INTERNSHIP: Quantum stochastic thermodynamics of light**

Classic thermodynamics is the phenomenological theory of the average behavior of heat and work for systems in thermal equilibrium. At the nanoscale, fluctuations dominate and systems generically operate far from thermal equilibrium [1]. The extension of thermodynamics to such situations was achieved only rather recently with the discovery of so-called fluctuations theorems. These theorems are statements of the second law of thermodynamics, and they constitute one of the most important breakthroughs in modern theoretical physics. At their core, they quantify that entropy only increases on average, and that processes with negative entropy production do occur, but they are exponentially unlikely.

The inception of these fluctuation theorems effectively opened a new field of research, which quickly adapted the name ‘stochastic thermodynamics’. In contrast to conventional thermodynamics, in stochastic thermodynamics work, heat, and also entropy production are defined along single trajectories of a classical system [2]. Naturally, the generalization of this new version of thermodynamics to quantum systems has posed a formidable task [3], which had lead to the development of rapidly growing field of research known as quantum thermodynamics. Intensive works were done along this line considering quantum close system exploring the role of quantum information, thermalisation or even quantum thermal machine [4].

However much more remain to do regarding quantum open systems even so they are the most commonly used in experiment to explore the quantum features. Among the large variety of those systems quantum optical devices are definitively those that allows the more accurate and profound exploration of quantum realm. This theoretical internship will be centred along this line and more precisely along the use of thermodynamics of trajectories [5] in quantum optical context.

[1] C. Jarzynski, Diverse phenomena, common themes

*Nat. Phys.*

**11**105 (2015) [2] U. Seifert, Stochastic thermodynamics, fluctuation theorems and molecular machines

*Rep. Prog. Phys.*

**75**126001 (2012) [3] M. Campisi, P. Hänggi and P. Talkner, Colloquium: quantum fluctuation relations: foundations and applications

*Rev. Mod. Phys.*

**83**771 (2011) [4] J. Millen and A. Xuereb, Perspective on quantum thermodynamics

*New J. Phys.*

**18**011002 (2016) [5] J. P. Garrahan and I. Lesanovsky, Thermodynamics of quantum jump trajectories

*Phys. Rev. Lett.*

**104**160601 (2010)

Interested candidates should contact Simon Pigeon (simon.pigeon@lkb.upmc.fr).

Theoretical internship.

Duration: 3 to 6 months.