Role of decoherence on adiabatic quantum motors

RAÚL A. BUSTOS MARÚN; LUCAS FERNÁNDEZ-ALCÁZAR; HORACIO M. PASTAWSKI

San Carlos de Bariloche

Encuentro; XIV Encuentro de Superficies y Materiales Nanoestructurados; 2014

Centro Atómico Bariloce

In recent years, several authors have explored the ideaof quantum machines [PRL 79, 10 (1997); PRL 96,130602 (2006); PRL 111, 060802 (2013)]. However, thetrue role of quantum mechanics on this type of devices issometimes blurry. In this work we study the role of deco-herence on a particular example of quantum machines:adiabatic quantum motors [PRL 111, 060802 (2013)].The working principle of this type of motors relies on re-verse quantum pumping and consequently it is expecteda strong effect, on the properties of the systems, of thedegree of coherence of the electrons that go through it.We study two different type of systems: a quantum-dotbased motor and a reverse-Thouless-pump motor. Theeffect of decoherence was modeled through the fictitiousprobes technique [PRB 33, 3020 (1986); PRB 41, 7411(1990)]. In the case of the reverse-Thouless-pump motorwe use a tight binding Hamiltonian to model the system,which allow us, on one hand, to include the effect of de-coherence in a more realistic way and, on the other, toanalyze the deviations from the approximations used inprevious works [PRL 111, 060802 (2013)]. On both exam-ples we study the effect of decoherence on the maximumwork performed per cycle, the friction coefficient, and theefficiency of the motor.