Generalized quantum Langevin equations from the forward-backward path integral
Kazuhiro Tsusaka · Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics · 1999
Kleinert and Shabanov [H. Kleinert and S. V. Shabanov, Phys. Lett. A 200, 224 (1995)] have derived the quantum Langevin equations from the Feynman-Vernon forward-backward path integral for a density matrix of a quantum system in a thermal oscillator bath. However, their derivation is confined to an Ohmic case. In this paper we derive the generalized quantum Langevin equations from the forward-backward path integral, by extending the Kleinert-Shabanov method to a general case.