Compensation of phonon-induced renormalization of vacuum Rabi splitting in large quantum dots: Towards temperature-stable strong coupling in the solid state with quantum dot-micropillars

Abstract

We study experimentally the influence of temperature on the emission characteristics of quantum dotmicropillars in the strong coupling regime of cavity quantum electrodynamics (cQED). In particular, we investigate its impact on the vacuum Rabi splitting (VRS) and we address the important question of the temperature stability of the coherent coupling regime in a semiconductor system, which is relevant in view of both fundamental study and future applications. To study the temperature dependence we investigate an unprecedentedly large number of strong coupling cases (89) in a wide temperature range from 10 up to 50 K, which constitutes a good basis for statistical analysis. The experiment indicates a statistically significant increase of the VRS with temperature in contrast to an expected decrease of the VRS due to the dephasing induced by acoustic phonons. From the theoretical point of view, the phonon-induced renormalization of the VRS is calculated using a real-time path-integral approach for strongly confined quantum dots (QDs), which allows for a numerical exact treatment of the coupling between the QD and a continuum of longitudinal acoustic phonons. The absence of the expected decrease of the VRS with temperature in our experimental data can be attributed to a unique optical property of laterally extended In 0.4 Ga 0.6 As QDs used in this study. Their electronic structure facilitates an effective temperature-driven increase of the oscillator strength of the excitonic state by up to 40% in the given temperature range. This leads to enhanced light-matter interaction and overcompensates the phonon-related decrease of the VRS. The observed persistence of strong coupling in the presence of phonon-induced decoherence demonstrates the appealing possibility to counteract detrimental phonon effects in the cQED regime via engineering the electronic structure of QDs.

Non-Markovian features in semiconductor quantum optics: quantifying the role of phonons in experiment and theory

“…Examples are matrix product state evolution techniques [111][112][113][114] or the real-time path integral method [33,115] in which the time evolution is discretized and the dissipative quantum kinetics becomes solvable due to the finite memory of the dissipative kernel, here of the acoustic phonons. Within the path-integral method technique, excellent agreement between theory and experiment has been demonstrated for state-preparation protocols [25], and the description of phonon-induced dephasing of coupled QD-microcavity systems in the strong coupling regime of cavity quantum electrodynamics [116,117].…”

Distinctive characteristics of carrier-phonon interactions in optically driven semiconductor quantum dots

“…The phonon impact on this critical λ value manifests itself in a pronounced dependence on the temperature [154]. For less confined larger QDs a temperature dependent change of the wave function extension of the state from which the emission takes place results in an effectively temperature dependent strength of the dipole coupling, which can overcompensate the reduction of the vacuum Rabi frequency [236].…”

Acousto-optical phonon excitation in cubic piezoelectric slabs and crystal growth orientation effects

“…While usually leading to a degradation of electronic performance, electron-phonon interactions can be employed to design device characteristics by appropriate geometry and well-controlled external conditions [2]. Recently, there have been several studies on the effect of phonons on excited states, utilizing phonons to achieve population inversion in InGaAs quantum dot systems [3][4][5][6].…”