Models for local Ohmic quantum dissipation

We propose a family of master equations for local quantum dissipation. The master equations are constructed in the form of Lindblad generators, with the constraints that the dissipation be strictly linear (i.e., Ohmic), isotropic, and translationally invariant. The resulting master equations are given in both the Schrödinger and Heisenberg forms. We obtain fluctuation-dissipation relations, and discuss the relaxation of average kinetic energy to effective thermal equilibrium values. We compare our results for one dimension to the Dekker master equation [H. Dekker, Phys. Rep. 80, 1 (1981)], which can be interpreted as a low-length-scale approximation of our model, as well as the Caldeira-Leggett master equation [A.O. Caldeira and A. J. Leggett, Physica (Utrecht) A 121, 587 (1983)].