Quantum Fermi's golden rule for semiconductor nanodevices

Abstract

AbstractWe 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. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)