C. Jarlov

Bound and anti-bound biexciton in site-controlled pyramidal GaInAs/GaAs quantum dots

We present a detailed study of biexciton complexes formed in single, site-controlled pyramidal GaInAs/GaAs quantum dots (QDs). By using power dependent measurements and photon correlation spectroscopy, we identify the excitonic transitions of a large number of pyramidal QDs, exhibiting both positive and negative biexciton binding energies. Separation of charges within the QD, caused by piezoelectric fields, is believed to be responsible for the positive to negative crossover of the biexciton binding energy with increasing QD size. In particular, QDs exhibiting vanishing biexciton binding energies are evidenced, with potential applications in quantum information processing.

Site-controlled quantum dots coupled to a photonic crystal molecule

Two site-controlled quantum dots (QDs) were integrated in a photonic crystal molecule (PCM) formed by L3 nanocavities. A statistical analysis of the coupled cavity modes demonstrated the formation of bonding and anti-bonding delocalized PCM states. Excitonic transitions belonging to each QD were identified by scanning micro-photoluminescence spectroscopy. Co-polarization of the QDs photoluminescence with the coupled cavity modes provides evidence for the simultaneous coupling of two spatially separated QDs to the same PCM mode.

Exciton dynamics in a site-controlled quantum dot coupled to a photonic crystal cavity

Exciton and cavity mode (CM) dynamics in site-controlled pyramidal quantum dots (QDs), integrated with linear photonic crystal membrane cavities, are investigated for a range of temperatures and photo-excitation power levels. The absence of spurious multi-excitonic effects, normally observed in similar structures based on self-assembled QDs, permits the observation of effects intrinsic to two-level systems embedded in a solid state matrix and interacting with optical cavity modes. The coupled exciton and CM dynamics follow the same trend, indicating that the CM is fed only by the exciton transition. The Purcell reduction of the QD and CM decay times is reproduced well by a theoretical model that includes exciton linewidth broadening and temperature dependent non-radiative processes, from which we extract a Purcell factor of 17 ± 5. For excitation powers above QD saturation, we show the influence of quantum wire barrier states at short delay time, and demonstrate the absence of multiexcitonic background emission.

Effect of Pure Dephasing and Phonon Scattering on the Coupling of Semiconductor Quantum Dots to Optical Cavities

We investigate the effect of decoherence mechanisms in semiconductor quantum dot-cavity systems by performing photoluminescence measurements of InGaAs/GaAs site-controlled quantum dots coupled to photonic crystal cavities and comparing the results to a theoretical model.

1D and 2D arrays of coupled photonic crystal cavities with a site-controlled quantum wire light source

We investigated experimentally 1D and 2D arrays of coupled L3 photonic crystal cavities. The optical modes of the coupled cavity arrays are fed by a site-controlled quantum wire light source. By performing photoluminescence measurements and relying on near-field calculation of the cavitiy modes, we evidence optical coupling between the cavities as well as supermode delocalization. In particular, for small cavity separations, fabrication induced disorder effects are shown to be negligible compared to optical coupling between cavities.

Deterministic radiative coupling of two semiconductor quantum dots to the optical mode of a photonic crystal nanocavity

A system of two site-controlled semiconductor quantum dots (QDs) is deterministically integrated with a photonic crystal membrane nano-cavity. The two QDs are identified via their reproducible emission spectral features, and their coupling to the fundamental cavity mode is established by emission co-polarization and cavity feeding features. A theoretical model accounting for phonon interaction and pure dephasing reproduces the observed results and permits extraction of the light-matter coupling constant for this system. The demonstrated approach offers a platform for scaling up the integration of QD systems and nano-photonic elements for integrated quantum photonics applications.

Propagation losses in photonic crystal waveguides: effects of band tail absorption and waveguide dispersion

Propagation losses in GaAs-based photonic crystal (PhC) waveguides are evaluated near the semiconductor band-edge by measuring the finesse of corresponding L-n cavities. This approach yields simultaneously the propagation losses and the mode reflectivity at the terminations of the cavities. We demonstrate that the propagation losses are dominated by band tail absorption for shorter wavelengths and by fabrication disorder related scattering, near the photonic band edge, for longer wavelengths. Strategies for minimizing losses in such elongated cavities and waveguides are discussed, which is important for the monolithic integration of light sources with such optical elements

Deterministic coupling of a system of multiple quantum dots to a single photonic cavity mode

We fabricated and studied a system comprising four site-controlled semiconductor quantum dots (QDs) embedded in a linear photonic crystal membrane cavity. The excellent position control and small spectral broadening permit coupling of the emission of all four QDs to the same photonic cavity modes. This is corroborated by co-polarization of the QD and cavity emission lines, as well as reduction in decay time, both with characteristic dependence on QD-cavity energy detuning. Scaling up to larger QD systems is discussed.

Probing disorder and mode localization in photonic crystal cavities using site-controlled quantum dots

The impact of optical disorder on photon propagation in long Ln photonic crystal cavities is investigated using spectrally resolved imaging, group index measurements, and selective mode excitation with site-controlled quantum dots. Mobility and diffusive edges, separating localized, diffusive, and dispersive regimes, are consistently identified. In situ probing of the photonic modes demonstrates the low impact of disorder in the dispersive regime and the transition to phase-distorted modes in the diffusive regime. The analysis yields criteria for designing photonic crystal waveguides for efficient single photon transport.

Site-controlled quantum dots coupled to photonic crystal cavities and waveguides

We investigate the optical coupling of excitons confined in site-controlled semiconductor quantum dots (QDs) with the modes of photonic crystal (PhC) cavities membrane cavities and waveguides. The structures are fabricated by organometallic vapor phase epitaxy of InGaAs/GaAs heterostructures on patterned (111)B GaAs substrates combined with electron-beam-based nanolithography. We elucidate the role of pure dephasing and phonon interaction on the weak exciton-cavity mode coupling, and demonstrate the simultaneous coupling of several QDs to the same optical mode of various PhC cavity configurations. In addition, coupling of QD systems to PhC waveguides for implementing single photon transport in the face of optical disorder is studied. Implications on the potential of constructing integrated quantum photonic circuits for on-chip manipulation of quantum light will be discussed.