Quantum Thermodynamics of Open Quantum Systems: Nature of Thermal Fluctuations

We investigate the thermodynamic behavior of open quantum systems through the Hamiltonian of Mean Force, focusing on two models: a two-qubit system interacting with a thermal bath and a Jaynes-Cummings Model without the rotating wave approximation. By analyzing both weak and strong coupling regimes, we uncover the impact of environmental interactions on quantum thermodynamic quantities, including specific heat capacity, internal energy, and entropy. Further, the ergotropy and entropy production are computed. We also explore the thermodynamic uncertainty relation, which sets an upper bound on the signal-to-noise ratio.