Quantum Work Statistics at Strong Reservoir Coupling
Work statistics are an important concept in quantum thermodynamics and contain rich information about the non-equilibrium behaviour of open quantum systems. However, determining these statistics becomes a formidable task when environmental interactions are significant, requiring the calculation of the full eigenspectrum of the combined system and reservoir. In this talk I will discuss how to circumvent this issue by using the polaron transformation, which is a technique that can map a spin system into a frame in which weak-coupling theory is applicable. The mapping is unitary and thus preserves the statistics of work, allowing for a direct calculation of the work distribution in strong coupling regimes. This polaron approach maintains consistency with the laws of stochastic thermodynamics, correctly reproducing key predictions such as the fluctuation theorems. As an application I will focus on a Landau-Zener transition at strong coupling; here we observe clear signatures in the work distribution such as renormalisation and increased dispersion due to the non-negligible coupling to the environment. These results provide a new method for studying the stochastic thermodynamics of driven quantum systems beyond Markovian, weak-coupling regimes.