Nonmonotonic Field Dependence of Damping and Reappearance of Rabi Oscillations in Quantum Dots

Abstract

The dynamics of strongly confined laser driven semiconductor quantum dots coupled to phonons is studied theoretically by calculating the time evolution of the reduced density matrix using a numerical path integral method. We explore the cases of long pulses, strong dot-phonon and dot-laser coupling, and high temperatures, which, up to now, have been inaccessible. We find that the phonon-induced damping of Rabi rotations is a nonmonotonic function of the laser field that is increasing at low fields and decreasing at high fields. This results in a reappearance of Rabi rotations at high fields. This phenomenon is of a general nature which occurs for all temperatures and carrier-phonon coupling strengths.

Effect of detuning on the phonon induced dephasing of optically driven InGaAs/GaAs quantum dots

“…For example, if the driving-field is strong enough, will the intensity damped Rabi rotation reappear? 6,15 Also, can one observe consequences of the phonon bath memory? 11 Conversely, can the phonon bath be used as a resource?…”

“…[8][9][10][11][12][13][14] A number of alternative approaches for calculating the dephasing have been studied, including a numerically exact approach. 15 Our model treats the quantum dot as an optically driven two-level system coupled to a bath of bosons, in this case LA-phonons. A transformation from the exciton basis to the optically dressed states, the energy eigen-states of the optically driven two-level system, results in a stationary frame where the exciton-phonon interaction is treated as a second-order perturbation.…”

The role of phonons for exciton and biexciton generation in an optically driven quantum dot

“…For the Hamiltonian dynamics within the model established by Eqs. (1), (4) and (8), also a numerically complete treatment without any further approximations to the light-matter or the carrier-phonon coupling has been implemented using a real-time path-integral approach [130,131,132,133,134]. Taking these numerically complete solutions as a benchmark, direct comparisons have been performed for the correlation expansion [135,136], the time-convolutionless formulation [127], and master equation [127] approaches.…”

“…However, it should be noted that this is not an undamping in the time regime such as, e.g., the revival of Rabi oscillations in the Jaynes-Cummings model [173]. This behavior has therefore been termed the reappearance of Rabi rotations [131]; an example is shown in Fig. 7.…”

“…The impact of the interaction of a QD exciton with acoustic phonons on the damping of Rabi rotations has been the subject of many theoretical works [123,129,169,125,119,120,64,127,136,170,131,171]. Besides analyzing specific experimental conditions, these studies have also been motivated by the exemplary character of the Hamiltonian describing a bosonic bath coupled to a two-level system [65,48,116].…”