Testing quantum microscopic reversibility using quantum optics

Quantum mechanics can be dramatically different from classical physics as quantum states can be in superposition, while quantum optics has provided a promising platform for exploring quantum natures in the microscopic regime. Recently, it has been actively studied how quantum coherence changes the laws of thermodynamics from both thermodynamics and quantum information perspectives. We propose and experimentally test quantum modification for the principle of microscopic reversibility, a symmetry relation between forward and backward state transitions when a system is interacting with a thermal heat bath. We show that quantum modification plays a critical role in the low-temperature limit, while the quantum-to-classical transition occurs at a high temperature. The experimental demonstration is done in an optical setup by interacting coherent states with thermal states using a beam-splitter, followed by heterodyne detection.