  A quantum analog of friction (understood as a completely positive, Markovian,
translation-invariant and phenomenological model of dissipation) is known to be
in odds with the detailed balance in the thermodynamic limit. We show that this
is not the case for quantum systems with internal (e.g. spin) states
non-adiabatically coupled to translational dynamics. For such systems, a
quantum master equation is derived which phenomenologically accounts for the
frictional effect of a uniform zero temperature environment. A simple
analytical example is provided. Conjectures regarding the finite temperature
case are also formulated. The results are important for efficient simulations
of complex molecular dynamics and quantum reservoir engineering applications.

Quantum Physics