Measuring work and heat in ultracold quantum gases
Gabriele De Chiara (Queen's University Belfast)

The study of out-of-equilibrium thermodynamics has received a significant thrust thanks to the experimental advances in the control and manipulation of microscopic systems. Heat and work, two ubiquitous concepts in traditional thermodynamics, assume in this context the role of stochastic variables whose fluctuations can be ingeniously related to equilibrium properties, as is the case of the celebrated Jarzynski equality. In this seminar I will revise these concepts and discuss a feasible experimental scheme to direct measure heat and work in cold atomic setups. The method is based on a recent proposal which shows that work is a positive operator valued measure (POVM). I will show that the interaction between atoms and the light polarisation of a probe laser, as in atomic ensembles experiments, allows us to implement such POVM.
In this way the work done on or extracted from the atoms after a given process is encoded in the light quadrature that can be measured with a standard homodyne detection. The protocol allows one to verify fluctuation theorems and study properties of the non-unitary dynamics of a given thermodynamic process.

Ref.: G. De Chiara, A. J. Roncaglia, J. P. Paz, arXiv:1412.6116