Probing different regimes of strong field light–matter interaction with semiconductor quantum dots and few cavity photons (original) (raw)

Cavity versus dot emission in strongly coupled quantum dots-cavity systems

2011

We discuss the spectral lineshapes of N quantum dots in strong coupling with the single mode of a microcavity. Nontrivial features are brought by detuning the emitters or probing the direct exciton emission spectrum. We describe dark states, quantum nonlinearities, emission dips and interferences and show how these various effects may coexist, giving rise to highly peculiar lineshapes.

Single-photon nonlinearity of a semiconductor quantum dot in a cavity

2006

A single atom in a cavity is the model system of cavity quantum electrodynamics (CQED). The strong coupling regime between the atom and cavity-confined photon corresponds to the reversible exchange of energy between the two modes, and underpins a wide range of CQED phenomena with applications in quantum information science, including for example as quantum logic gates and as sources of entangled states. 2,3,4 An important advance was achieved recently when strong coupling between excitons and cavity photons was reported for the first time for localized quantum dots (QDs) in micron-size solid state cavities, 5-8 . This has significance in terms of scalability and integration with other optical devices, and could lead to the emergence of 'quantum optics on a chip' technology. However the results presented so far for quantum dots are in the linear regime, corresponding to coupling to the vacuum field (vacuum Rabi splitting); they are not a true QED effect and can equally well be described by classical physics as the coupling between two oscillators. 9 In this paper, we present evidence for a purely quantum phenomenon for the QD/cavity photon system, namely the increase in splitting of the levels when the mean number of photons in the cavity is increased. This corresponds to non-linearities on the single-photon scale: the presence of a single excitation in the cavity changes the level structure, affecting the emission energies for a second photon. Such results are a first step in demonstrating the promise of quantum dots for CQED applications.

Detuning effect in quantum dynamics of a strongly coupled single quantum dot–cavity system

Journal of Physics: Condensed Matter, 2008

The quantum dynamics of a strongly coupled single quantum dot-cavity system with non-zero detuning in a phonon bath is investigated theoretically in terms of a perturbation treatment based on a unitary transformation and an operator displacement. The decoherence due to phonons as a function of the detuning between the cavity mode and exciton is obtained analytically. It is shown that the detuning has a significant impact on the quantum dot exciton lifetime. In realistic experimental conditions, the calculated exciton lifetimes are in good agreement with recent experimental observation (Hennessy et al 2007 Nature 445 896).

Coherent optical spectroscopy of a single quantum dot (non)-resonantly coupled to a high-q microcavity

Electronic/Optical Coherence in Low Dimensional Semiconductors and Atomic Gases Session II

In recent experiments on coupled quantum dot (QD) optical cavity systems a pronounced interaction between the dot and the cavity has been observed even for detunings of many cavity linewidths. This interaction has been attributed to an incoherent phonon-mediated scattering process and is absent in atomic systems. Here, we demonstrate that despite its incoherent nature, this process preserves the signatures of coherent interaction between a QD and a strong driving laser, which may be observed via the optical emission from the off-resonant cavity. Under bichromatic driving of the QD, the cavity emission exhibits spectral features consistent with optical dressing of the QD transition. In addition to revealing new aspects of the off-resonant QD-cavity interaction, this result provides a new, simpler means of coherently probing QDs than traditional approaches and opens the possibility of employing off-resonant cavities to optically interface QD-nodes in quantum networks.

Correlations between axial and lateral emission of coupled quantum dot–micropillar cavities

Physical Review B, 2015

We analyze the occurrence of normal-mode coupling (NMC) in bimodal lasers attributed to the collective interaction of the cavity field with a mesoscopic number of quantum dots (QDs). In contrast to the conventional NMC here we observe locking of the frequencies and splitting of the linewidths of the eigenmodes of the system in the coherent coupling regime. The theoretical analysis of the incoherent regime is supported by experimental observations where the emission spectrum of one of the orthogonally polarized modes of a bimodal QD micropillar laser demonstrates a two-peak structure.

Coherent excitation of a strongly coupled quantum dot - cavity system

2009

We have studied the coherent excitation of a strongly coupled QD/photonic crystal cavity system. Time-resolved reflectivity measurements show the vacuum Rabi oscillation of the dot in the cavity. Next, we considered the resonant driving of a cavity-detuned dot, which efficiently populates the cavity mode. This cavity-controlled read-out channel allows high-resolution single quantum dot spectroscopy. Autocorrelation measurements on the cavity mode show antibunching and suggest the use of the resonantly driven QD/cavity system as an on-demand source of single photons with potentially near-unity indistinguishability.

Excitonic dynamics of a quantum dot coupled to a laser-driven semiconductor microcavity

Microelectronics Journal, 2008

Within the density matrix formalism, we report on the quantum control of the excitonic coherences in quantum dots coupled to a single mode field resonant semiconductor cavity. We use an external classical laser field to drive the dynamical response of the excitonic states. Dissipation mechanisms associated with the cavity field and the excitonic states are explicitly included in the model. Our numerical simulations of the excitonic dynamics are in good agreement with recent experimental reports. Furthermore, we compute and show how to tailor such a dynamics in the presence of the laser field by means of controlling the detuning between the laser and the cavity field frequencies. The results are analyzed with a view to implementing quantum control of local qubit operations.

Dephasing of Triplet-Sideband Optical Emission of a Resonantly Driven InAs/GaAs Quantum Dot inside a Microcavity

Physical Review Letters, 2011

Detailed properties of resonance fluorescence from a single quantum dot in a micropillar cavity are investigated, with particular focus on emission coherence in dependence on optical driving field power and detuning. Power-dependent series over a wide range could trace characteristic Mollow triplet spectra with large Rabi splittings of |Ω| ≤ 15 GHz. In particular, the effect of dephasing in terms of systematic spectral broadening ∝ Ω 2 of the Mollow sidebands is observed as a strong fingerprint of excitation-induced dephasing. Our results are in excellent agreement with predictions of a recently presented model on phonon-dressed QD Mollow triplet emission in the cavity-QED regime.

Exciton photon strong-coupling regime for a single quantum dot in a microcavity

2004

We report on the observation of the strong coupling regime between a single GaAs quantum dot and a microdisk optical mode. Photoluminescence is performed at various temperatures to tune the quantum dot exciton with respect to the optical mode. At resonance, we observe an anticrossing, signature of the strong coupling regime with a well resolved doublet. The Vacuum Rabi splitting amounts to 400 μeV and is twice as large as the individual linewidths.

Competition between pure dephasing and photon losses in the dynamics of a dot-cavity system

Physical Review B

We demonstrate that in quantum-dot cavity systems, the interplay between acoustic phonons and photon losses introduces novel features and characteristic dependencies in the system dynamics. In particular, the combined action of both loss mechanisms strongly affects the transition from the weak to the strong coupling regime as well as the shape of Mollow-type spectra in untypical ways. For weak coupling, where the spectra degenerate to a single line, we predict that their widths decrease with rising temperature.