Decoherence of an impurity in a one-dimensional fermionic bath with mass   imbalance
  We study the transport, decoherence and dissipation of an impurity interacting with a bath of free fermions in a one-dimensional lattice. Numerical simulations are made with the time-evolving block decimation method. We introduce a mass imbalance between the impurity and bath particles and find that the fastest decoherence occurs for a light impurity in a bath of heavy particles. By contrast, the fastest dissipation of energy occurs when the masses are equal. We present a simple model for decoherence in the heavy bath limit, and a linear density response description of the interaction which predicts maximum dissipation for equal masses. 
A.-M. Visuri, J. J. Kinnunen, J. E. Baarsma, and P. T\"orm\"a
cond-mat.quant-gas