Microscopic modelling of electronic-phase coherence versus energy dissipation plays a crucial role in the design and optimization of new-generation electronic quantum nanodevices, like quantum-cascade light sources and quantum logic gates; in this context, a variety of simulation strategies have been proposed and employed. The aim of this article is to discuss virtues versus intrinsic limitations of non-Markovian density-matrix approaches. More specifically, we shall show that the usual mean-field treatment employed to derive quantum-kinetic equations may lead to highly unphysical results, like negative distribution functions and non-dissipative carrier–optical phonon couplings. By means of a simple two-level model, we shall show that such limitations are expected to be particularly severe in zero-dimensional electronic systems—like quantum-dot nanostructures, potential constituents of quantum-computation devices—coupled to dispersionless phonon modes. Such a behaviour is in striking contrast with the case of Markovian treatments, where a proper combination of adiabatic limit and mean-field approximation guarantees a physically acceptable solution.

Electron–phonon dissipation in quantum nanodevices - Limitations of quantum-kinetic treatments / Iotti, Rita Claudia; Dolcini, Fabrizio; Montorsi, Arianna; Rossi, Fausto. - In: JOURNAL OF COMPUTATIONAL ELECTRONICS. - ISSN 1569-8025. - STAMPA. - 15:4(2016), pp. 1170-1178. [10.1007/s10825-016-0858-6]

Electron–phonon dissipation in quantum nanodevices - Limitations of quantum-kinetic treatments

IOTTI, Rita Claudia;DOLCINI, FABRIZIO;MONTORSI, Arianna;ROSSI, FAUSTO
2016

Abstract

Microscopic modelling of electronic-phase coherence versus energy dissipation plays a crucial role in the design and optimization of new-generation electronic quantum nanodevices, like quantum-cascade light sources and quantum logic gates; in this context, a variety of simulation strategies have been proposed and employed. The aim of this article is to discuss virtues versus intrinsic limitations of non-Markovian density-matrix approaches. More specifically, we shall show that the usual mean-field treatment employed to derive quantum-kinetic equations may lead to highly unphysical results, like negative distribution functions and non-dissipative carrier–optical phonon couplings. By means of a simple two-level model, we shall show that such limitations are expected to be particularly severe in zero-dimensional electronic systems—like quantum-dot nanostructures, potential constituents of quantum-computation devices—coupled to dispersionless phonon modes. Such a behaviour is in striking contrast with the case of Markovian treatments, where a proper combination of adiabatic limit and mean-field approximation guarantees a physically acceptable solution.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11583/2657046
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