Jarzynski Equality for Driven Quantum Field Theories

The fluctuation theorems, and in particular, the Jarzynski equality, are the most important pillars of modern nonequilibrium statistical mechanics. We extend the quantum Jarzynski equality together with the two-time measurement formalism to their ultimate range of validity—to quantum field theories. To this end, we focus on a time-dependent version of scalar ϕ^4. We find closed-form expressions for the resulting work distribution function, and we find that they are proper physical observables of the quantum field theory. Also, we show explicitly that the Jarzynski equality and Crooks fluctuation theorems hold at one-loop order independent of the renormalization scale. As a numerical case study, we compute the work distributions for an infinitely smooth protocol in the ultrarelativistic regime. In this case, it is found that work done through processes with pair creation is the dominant contribution