Temporal monitoring of nonresonant feeding of semiconductor nanocavity modes by quantum dot multiexciton transitions

Abstract

We experimentally investigate the nonresonant ͑⌬E Ͼ 5 meV͒ feeding of photons into the optical mode of a two-dimensional photonic crystal nanocavity by quantum dot multiexciton transitions. Power-dependent photoluminescence measurements reveal a superlinear power dependence of the mode emission, indicating that the emission stems from multiexcitons. By monitoring the temporal evolution of the photoluminescence spectrum, we observe a clear anticorrelation of the mode and single exciton emission; the mode emission quenches as the population in the system reduces toward the single exciton level while the intensity of the mode emission tracks the multiexciton transitions. Our results lend strong support to a recently proposed mechanism ͓M. Winger et al., Phys. Rev. Lett. 103, 207403 ͑2009͔͒ mediating the strongly nonresonant feeding of photons into the cavity mode.Semiconductor quantum dots ͑QDs͒ exhibit atomlike properties such as a discrete interband optical spectrum with nearly homogeneously broadened transitions and shell filling effects as carriers ͑electrons and holes͒ are added. As a result, they are natural candidates for conducting cavity quantum electrodynamics ͑cQED͒ experiments in the solid state. 1 Among the many potential applications of single QD-cavity structures are the efficient and deterministic generation of indistinguishable photons, 2 devices that exploit single photon quantum nonlinearities, 3 and ultralow threshold nanolasers. 4 While exhibiting many properties known from atom based cQED, a number of surprising deviations from this model system have been identified. For example, recent experiments have revealed pronounced emission from the cavity mode, even when all the discrete QD emission lines are spectrally detuned. 5-7 This effect has been attributed to phonon mediated dot-cavity interactions for small dot-cavity detunings up to a few meV. 8-11 However, nonresonant QD-cavity coupling was also observed for much larger detunings, up to ϳ20 meV ͑Refs. 5, 7, 12, and 13͒ which cannot be attributed to phonon mediated processes. Experimental investigations of such highly nonresonant coupling revealed apparently contradictory observations in photon autocorrelation and crosscorrelation measurements: 5-7,12 ͑i͒ the QD emission is strongly antibunched, ͑ii͒ the cavity emission is Poissonian while ͑iii͒ pronounced crosscorrelations exist between the QD and cavity mode emission. Winger et al. explained these observations by a model that links the strong off-resonant cavity mode emission to Purcell enhanced decay into a quasicontinuum of few particle states. 12 The coexistence of the discrete QD states, where all particles are confined in the dot, and the quasicontinuum, where some particles occupy states in the wetting layer is inherent to the mesoscopic nature of the QD confinement.In this Rapid Communication, we present experimental investigations of cavity mode feeding from spectrally detuned QD multiexciton states for a wide range of negative and positive single exciton-mode detunings ͑ QD − cav =...

Bichromatic dressing of a quantum dot detected by a remote second quantum dot

“…1 Cavity QED experiments in semiconductor quantum dots (QDs) 2 gave rise to a number of applications, particularly in quantum information processing and quantum networking, 3,4 as well as for single-photon emitters. [5][6][7] This is partly due to the simultaneous confinement of excitons and photons 2,[8][9][10][11] in these systems. If the two-level system is coherently driven by strong resonant excitation, mixed exciton-photon states (dressed states) are formed, which are at the origin of the wellknown Mollow triplet 12 observed in the optical emission of atoms 13 and QDs under resonant excitation.…”

“…If the two-level system is coherently driven by strong resonant excitation, mixed exciton-photon states (dressed states) are formed, which are at the origin of the wellknown Mollow triplet 12 observed in the optical emission of atoms 13 and QDs under resonant excitation. [14][15][16] Strong cavity emission also occurs even when the QD emitter is not in resonance with the cavity, 9 and several cavity-feeding mechanisms have been proposed 10,11 for this phenomenon, including the intermediation by acoustic phonons. 17 Simultaneous coupling of more than one QD to the same cavity mode (CM) is also possible when there is sufficient spectral and spatial overlap.…”

Fundamental Properties

“…Eventually it was realized [2,43,44] that the very non-resonant coupling, |Δ| > 10 meV, was dependent on the excitation energy and power of the QD and arose due to multi-excitons in the QD and their Coulomb-mediated correlations with carriers in the wetting layer. In the weak excitation regime, the spectrally very long-ranged couplings did not occur.…”

“…where the "row-stacked" version of the matrix X is 43) employing the vec operation yields and where the coupling matrix is given by…”

Time-Resolved Two-Pulse Excitation of Quantum Dots Coupled to a Photonic Crystal Cavity in the Purcell Regime

“…Therefore both the powerdependent and time-resolved response of the excitation and emission can be simultaneously studied, with the temporal resolution limited only by the duration of the laser pulse. For LIA, the radiative lifetime of an emitter is measured through the nonlinear response of the timeaveraged emission intensity, which is inherently different from time-resolved photo-detection methods using streak cameras [12] or photon correlation measurements [13].…”