arXiv subjects

Paweł Machnikowski

Publications and source records attributed to Paweł Machnikowski.

77 records · Page 5Linked to original sources

arXiv2010

Electron states, phonon-assisted relaxation and tunneling in self-assembled quantum dot molecules in an electric field

We present a theoretical analysis of the phonon-assisted relaxation in a system composed of two self-assembled vertically stacked quantum dots. We construct realistic model, which takes into account the geometry and strain distribution in the system. We calculate phonon-assisted relaxation rates between the two lowest states (in one- and two-electron cases). The relaxation rates and energy levels are studied as a function of external (axial) electric field and geometry of the structure (dot sizes). We show that the relaxation times can be as low as 1~ps but efficent relaxation occurs only for very finely tuned dots.

cond-mat.mes-hall↗

arXiv2009

Radiative and phonon-induced dephasing in double quantum dots

A simple method for describing the evolution of a quantum state of a double quantum dot system interacting simultaneously with the electromagnetic environment and with the lattice modes is developed. It is shown that the joint action of the two reservoirs leads to nontrivial effects in the system dephasing. As an example, the impact of phonon-induced initial dephasing on the radiative decay of delocalized exciton states is discussed.

cond-mat.mes-hall↗

arXiv2009

Collective luminescence and phonon-induced processes in double quantum dots

We study the evolution of a quantum state of a double quantum dot system interacting with the electromagnetic environment and with the lattice modes, in the presence of a coupling between the two dots. We propose a unified approach to the simulation of the system evolution under joint impact of the two reservoirs. We discuss the sub- and superradiant radiative decay of the system, the phonon-induced decay of entanglement between the dots, and the transfer of excitation between them.

cond-mat.mes-hall↗

arXiv2009

Singlet-triplet dephasing in asymmetric quantum dot molecules

We discuss pure dephasing of singlet-triplet superpositions in two-electron double quantum dots due to elastic phonon scattering. We generalize our previous results to a system built of two non-identical dots. We show that the asymmetry must be very strong in order to considerably affect the dephasing rate.

cond-mat.mes-hall↗

arXiv2006

Change of decoherence scenario and appearance of localization due to reservoir anharmonicity

Although coupling to a super-Ohmic bosonic reservoir leads only to partial dephasing on short time scales, exponential decay of coherence appears in the Markovian limit (for long times) if anharmonicity of the reservoir is taken into account. This effect not only qualitatively changes the decoherence scenario but also leads to localization processes in which superpositions of spatially separated states dephase with a rate that depends on the distance between the localized states. As an example of the latter process, we study the decay of coherence of an electron state delocalized over two semiconductor quantum dots due to anharmonicity of phonon modes.

quant-ph↗