Quantum Fermi's golden rule for semiconductor nanodevices

We shall revisit the conventional adiabatic or Markov approximation, stressing its intrinsic failure in describing the proper quantum-mechanical evolution of a generic subsystem interacting with its environment. In particular, we shall show that - contrary to the semiclassical case - the Markov limit does not preserve the positivedefinite character of the corresponding density matrix, thus leading to highly non-physical results. To overcome this problem, we shall propose an alternative adiabatic procedure which (i) in the semiclassical limit reduces to the standard Fermi's golden rule, and (ii) describes a genuine Limblad evolution, thus providing a reliable/robust treatment of energy-dissipation and dephasing processes in electronic quantum devices. Compared to standard master-equation formulations, the proposed approach does not involve/require any reduction or average procedure, exactly as for the derivation of the well known Fermi's golden rule.