Guillaume Tarel

Explanation of Photon Correlations in the Far-Off-Resonance Optical Emission from a Quantum-Dot-Cavity System

Martin Winger, Thomas Volz, Guillaume Tarel, Stefano Portolan, Antonio Badolato, Kevin J. Hennessy, Evelyn L. Hu, Alexios Beveratos, Jonathan Finley, Vincenzo Savona, and Ataç Imamoğlu Institute of Quantum Electronics, ETH Zurich, 8093 Zurich, Switzerland Institute of Theoretical Physics, Ecole Polytechnique Fédérale de Lausanne EPFL, CH-1015 Lausanne, Switzerland Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627, USA California NanoSystems Institute, University of California, Santa Barbara, California 93106, USA CNRS Laboratoire Photonique et Nanostructures, Route de Nozay, F-91460 Marcoussis, France Walter Schottky Institut, Am Coulombwall 3, D-85748 Garching, Germany (Dated: November 23, 2009)

Linear spectrum of a quantum dot coupled to a nanocavity

We develop a theoretical formalism to model the linear spectrum of a quantum dot embedded in a high-quality 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.

Assessing the Future of Renewable and Smart Grid Technologies in Regional Energy Systems

SummaryIn this paper we present the regional techno-economic model ETEM, designed for the analysis of regional energy/environment systems and we show how it can be used to explore the possible penetration of new technologies in a region corresponding roughly to the canton of Geneva. We investigate three scenarios with different constraints on CO2 emissions and electricity imports and show the essential role played by new technologies, linked through a smart grid, in the effort toward a sustainable energy system. We strengthen our conclusion with a stochastic approach dealing with uncertainty in future electricity prices and electric car technology penetration.

Emission spectrum of a quantum dot embedded in a nanocavity

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.

Photoluminescence from a quantum dot-cavity system

: This chapter describes the photoluminescence properties of a solid-state cavity quantum electrodynamics (CQED) system, consisting of a single quantum dot (QD) coupled to a photonic crystal (PC) defect cavity. It addresses in particular the phenomenon of cavity feeding, that is, the efficient luminescence at the cavity frequency even for large detunings. The chapter presents a theoretical model of cavity feeding that takes into account the coupling to wetting-layer states. We find excellent agreement between simulations based on this model and experimental observations in the case of large detuning. In addition, the influence of acoustic phonons for the small-detuning case is discussed.

Phonon-mediated exciton-photon coupling in site-controlled quantum-dot-nanocavity systems

We show that far off-resonance exciton-photon coupling reported for self-assembled quantum dots in optical microcavities is not universal, and demonstrate that site-controlled dots exhibit clean phonon-mediated resonant coupling.

Active Semiconductor Nanophotonics based on Deterministic Quantum Wire and Dot Systems

We investigate the use of MOVPE-grown ordered nanostructures on non-planar substrates for quantum nano-photonics and quantum electrodynamics-based applications. The mastering of surface adatom fluxes on patterned GaAs substrates allows for forming nanostrucutres confining well-defined charge carrier states. An example given is the formation of quantum dot (QD) molecules tunneled-coupled by quantum wires (QWRs), in which both electron and hole states are hybridized. In addition, it is shown that the high degree of symmetry of QDs grown on patterned (111)B substrates makes them efficient entangled-photons emitters. Thanks to the optimal control over their position and emission wavelength, the fabricated nanostructures can be efficiently coupled to photonic nano-cavities. Low-threshold, optically pumped QWR laser incorporating photonic crystal (PhC) membrane cavities are demonstrated. Moreover, phononmediated coupling of QD exciton states to PhC cavities is observed. This approach should be useful for integrating more complex systems of QWRs and QDs for forming a variety of active nano-photonic structures.

Monte Carlo model for the photoluminescence kinetics of a quantum dot embedded in a nanocavity

We address the problem of the photoluminescence of a quantum (QD) dot in a nanocavity, with focus on the case of nonzero detuning. In this regime, experiments have shown that strong emission from the cavity-like peak is still present for dot-cavity detuning exceeding 10 meV, which seems puzzling. We will discuss the general theory of cavity feeding, due to the relaxation and recombination kinetics of a multiply excited QD. We first compute the multi-exciton manifolds using a configuration-interaction scheme, starting from a truncated single-particle basis. We then run Monte-Carlo paths of excitation-emission kinetics on these states. This allows to extract photoluminescence spectra and two-photon correlation curves. The agreement with experimental data[1, 2] is very good. Our result shows unambiguously that the cavity feeding mechanism at large detunings can be attributed to excited-state multiexciton radiative decay (mostly biexcitons), also involving states in the wetting layer continuum.