Quantum effective action for dissipative semiclassical dynamics (opens in new tab)

Using the quantum effective action in the Schwinger-Keldysh formalism, we derive quantum corrections to the semiclassical Langevin dynamics of a dissipative system governed by a macroscopic degree of freedom. We discuss the connection with the Ehrenfest theorem and show that, in the low-temperature and weak-damping regime, quantum corrections are determined by the zero-point energy of fluctuations evaluated at the classical underdamped frequen...