Phonon-assisted transitions from quantum dot excitons to cavity photons

Abstract

For a single semiconductor quantum dot embedded in a microcavity, we theoretically and experimentally investigate phonon-assisted transitions between excitons and the cavity mode. Within the framework of the independent boson model we find that such transitions can be very efficient, even for relatively large exciton-cavity detunings of several millielectron volts. Furthermore, we predict a strong detuning asymmetry for the exciton lifetime that vanishes for elevated lattice temperature. Our findings are corroborated by experiment, which turns out to be in good quantitative and qualitative agreement with theory

Cavity quantum electrodynamics with semiconductor quantum dots: Role of phonon-assisted cavity feeding

“…In a recent paper, 32 it has been demonstrated theoretically and experimentally that, besides phonon dephasing, there exists another phonon-mediated feeding channel for the cavity that works efficiently over a broad detuning range of several meV. Similar results have been independently obtained by other authors.…”

Measuring the effective phonon density of states of a quantum dot in cavity quantum electrodynamics

“…Previous work on detuning-dependent decay rates in a PC nanocavity has established the importance of phonon dephasing for the Purcell enhancement. 12 In the present experiment, the dynamics of a single QD enables a direct measurement of the phonon decoherence mechanism, which is possible since the QD is coherently coupled to a cavity. Our work constitutes a significant extension, into the realm of coherent quantum optics, of previous work where proper account of the QD fine structure enabled probing the incoherent local optical density of states (LDOS).…”

“…4,5 Cavity quantum-electrodynamics (QED) experiments in solid-state systems have yielded major breakthroughs within the last decade, including the observation of Purcell enhancement, 6,7 strong coupling between a single QD and a photon, 8,9 and non-Markovian dynamics. 10 A number of surprises have emerged, distinguishing QD-based QED from its atomic counterpart, including the breakdown of the pointdipole description of light-matter interaction, 11 the role of phonon dephasing, [12][13][14] and multiple-charge transitions. 15,16 In this paper, we explore the role of environmental fluctuations by employing a QD embedded in a nanocavity as a sensitive probe of the phonon dephasing processes in a photoniccrystal (PC) nanomembrane.…”

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

“…Also for dots in cavities phonons can play a decisive role, e.g., for the dephasing [87,88,89,90,91], the photon statistics [92,58,93,94], the indistinguishability of photons [95] as well as for providing a dot-cavity coupling in the case of non-resonant QD and cavity modes where phenomena like off-resonant cavity feeding have been found [96,82,97,98,99,100,101,102]. Although such systems are not at the focus of the present review, we note in passing that in this case, additional relaxation mechanisms, in particular cavity losses, may become of importance.…”