A new master equation describing the irreversible process of a quantum mechanical Brownian particle is proposed. The master equation is shown to obey the symmetry of detailed balance leading to a quantum analog of the reciprocity relations, and the fluctuation-dissipation theorem is obtained. The method is applied to the damped harmonic oscillator. The relation to previous approaches is discussed.

• Received 29 March 1982

DOI:https://doi.org/10.1103/PhysRevLett.50.1335