Decoherence and Quantum Transport in Nanodevices

M. Arzeo

Christophe Couteau

Robert F. O’Connell

Damien Querlioz, Jérôme Saint-Martin, Arnaud Bournel +1 more

This paper examines the phonon-induced electron decoherence in semiconductor nanostructures and nanodevices within the Wigner transport equation, solved using a particle Monte Carlo technique. The Wigner-Boltzmann formalism is first established as a relevant and original approach to modeling electron quantum decoherence in semiconductors. The simulation of the time evolution of a free wave-packet then allows analyzing the competition between decoherence and wave-packet expansion in a semiconductor. It is additionally argued that decoherence occurs faster than in the widely studied case of quantum Brownian motion. The simulation of a wave packet interacting with a tunnel barrier allows studying the electron localization induced by decoherence. The case of a wave packet interacting with a double barrier puts forward the mechanism of decoherence-induced transition from resonant to sequential transport through a bound state. Finally the simulation of resonant tunneling devices shows how these phenomena take place in nanodevices and highlights the transition from the quantum transport regime to the semiclassical transport regime induced by phonon scattering.

Pei-Yun Yang, Wei-Min Zhang

In this review article, we present a non-equilibrium quantum transport theory for transient electron dynamics in nanodevices based on exact Master equation derived with the path integral method in the fermion coherent-state representation. Applying the exact Master equation to nanodevices, we also establish the connection of the reduced density matrix and the transient quantum transport current with the Keldysh nonequilibrium Green functions. The theory enables us to study transient quantum transport in nanostructures with back-reaction effects from the contacts, with non-Markovian dissipation and decoherence being fully taken into account. In applications, we utilize the theory to specific quantum transport systems, a variety of quantum decoherence and quantum transport phenomena involving the non-Markovian memory effect are investigated in both transient and stationary scenarios at arbitrary initial temperatures of the contacts.