In a coupled quantum-dot nano-cavity system, the photoluminescence from an off-resonance cavity mode exhibits strong quantum correlations with the quantum dot transitions, even though its autocorrelation function is classical. Using new pump-power dependent photon-correlation measurements, we demonstrate that this seemingly contradictory observation that has so far defied an explanation stems from cascaded cavity photon emission in transitions between excited multiexciton states. The mesoscopic nature of quantum dot confinement ensures the presence of a quasicontinuum of excitonic transitions part of which overlaps with the cavity resonance.A quantum dot (QD) coupled to a photonic crystal cavity provides a promising system for studying cavity quantum-electrodynamics (QED) in the solid state [1,2]. In contrast to their atom-based counterparts, these systems exhibit features that arise from their complex environment. A common effect that surfaced in previous experiments is strong off-resonant emission of a cavity mode (CM) containing one or multiple QDs. Photon correlation measurements revealed that the cavity-mode emission is anti-correlated with the QD excitons at the level of single quanta, proving that cavity feeding is mediated solely by a single QD [3,4]. Surprisingly, however, the photon stream emitted by the far off-resonant CM did not show any significant quantum correlations. Previous experimental [5,6,7] and theoretical [8,9] investigations have focused on explaining cavity feeding in terms of dephasing of the QD excitons mediated either by coupling to acoustic phonons or to free carriers. However, all of the attempts to describe cavity feeding using Markovian dephasing of the fundamental exciton line fail to explain the above mentioned photon correlation signatures that appear to be true for all studied QD cavity-QED systems.In this Letter, we unequivocally demonstrate that the far off-resonant excitation of the CM is solely due to the mesoscopic nature of quantum dot confinement, which in turn leads to an energetically broad cascaded emission of the QD. In this setting, cavity feeding and its photon correlation signatures can be regarded as an intrinsic feature of QD-cavity systems that arises from the complicated QD multi-exciton level structure. We carry out pump-power dependent photoluminescence (PL) as well as photon auto-and cross-correlation measurements on a nano-structure incorporating a single QD embedded in a photonic crystal (PC) defect cavity [3]. To explain our experimental observations, we develop a new theoretical model for the QD-cavity system, perform numerical calculations of its semi-classical dynamics and compare its predictions with the new experimental findings. While a quantitative comparison between numerical and experimental results is intrinsically difficult, the qualitative agreement we achieve is excellent. In particular, the unusual correlation features found experimentally are naturally reproduced by the model and the simulations.Before proceeding, we remark that acoustic...

We demonstrate that the emission characteristics of site-controlled InGaAs/GaAs single quantum dots embedded in photonic crystal slab cavities correspond to single confined excitons coupled to cavity modes, unlike previous reports of similar systems based on self-assembled quantum dots. By using polarization-resolved photoluminescence spectroscopy at different temperatures and a theoretical model, we show that the exciton-cavity interaction range is limited to the phonon sidebands. Photon-correlation and pump-power dependence experiments under nonresonant excitation conditions further establish that the cavity is fed only by a single exciton.

We develop a theoretical formalism to model the linear spectrum of a quantum dot embedded in a highquality cavity, in the presence of an arbitrary mechanism modifying the homogeneous spectrum of the quantum dot. Within the simple assumption of Lorentzian broadening, we show how the known predictions of cavity quantum electrodynamics are recovered. We then apply our model to the case where the quantum dot interacts with an acoustic-phonon reservoir, producing phonon sidebands in the response of the bare dot. In this case, we show that the sidebands can sustain the spectral response of the cavitylike peak even at moderate dot-cavity detuning, thus, supporting recent experimental findings.

We study the system of two quantum dots lying on the central plane of a planar semiconductor microcavity. By solving the full Maxwell problem, we demonstrate that the rate of resonant excitation transfer between the two dots decays as d–1/2 as a function of the distance d at long distance. This very longrange mechanism is due to the leaky and guided modes of the microcavity, which act as effective radiative transfer channels. At short distance, the d–3 dependence of the Förster mechanism, induced by the electrostatic dipole–dipole interaction, is recovered. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

We model the emission spectrum of a quantum dot embedded in a (e.g. photonic crystal) nanocavity, using a semi-classical approach to describe the matter-field interaction. We start from the simple model of a quantum dot as a two-level system, and recover the result expected from cavity quantum electrodynamics. Then, we study the influence of electron-acoustic-phonons interaction. We show that the surrounding semiconductor plays an essential role in the emission spectrum in strong coupling.Schematic of the L1 cavity of the 2D triangular PHC with embedded quantum dot.