Ignacio Franco and I derive a general but simple formula for decoherence times. As it demonstrates, the initial purity decay is Gaussian and the associated timescale is determined only by the fluctuations of system and bath operators that enter into the interaction Hamiltonian. Using this formula, we also showed that mixed quantum-classical methods like Ehrenfest dynamics can capture decoherence correctly provided the initial conditions are sampled from a Wigner distribution.
This paper is published in J. Phys. Chem. Lett., check it out!