arXiv subjects

Fabrice P. Laussy

Publications and source records attributed to Fabrice P. Laussy.

47 records · Page 3Linked to original sources

arXiv2012

Fluctuation induced luminescence sidebands in the emission spectra of resonantly driven quantum dots

We describe how complex fluctuations of the local environment of an optically active quantum dot can leave rich fingerprints in its emission spectrum. A new feature, termed "Fluctuation Induced Luminescence" (FIL), is observed to arise from extremely rare fluctuation events that have a dramatic impact on the response of the system-so called "black swan" events. A quantum dissipative master equation formalism is developed to describe this effect phenomenologically. Experiments performed on single quantum dots subject to electrical noise show excellent agreement with our theory, producing the characteristic FIL sidebands.

cond-mat.mes-hall↗

arXiv2011

Generation of a two-photon state from a quantum dot in a microcavity under incoherent and coherent continuous excitation

We analyze the impact of both an incoherent and a coherent continuous excitation on our proposal to generate a two-photon state from a quantum dot in a microcavity [New J. Phys. 13, 113014 (2011)]. A comparison between exact numerical results and analytical formulas provides the conditions to efficiently generate indistinguishable and simultaneous pairs of photons under both types of excitation.

cond-mat.mes-hall↗

arXiv2011

Climbing the Jaynes-Cummings ladder by photon counting

We present a new method to observe direct experimental evidence of Jaynes--Cummings nonlinearities in a strongly dissipative cavity quantum electrodynamics system, where large losses compete with the strong light-matter interaction. This is a highly topical problem, particularly for quantum dots in microcavities where transitions from higher rungs of the Jaynes--Cummings ladder remain to be evidenced explicitly. We compare coherent and incoherent excitations of the system and find that resonant excitation of the detuned emitter make it possible to unambiguously evidence few photon quantum nonlinearities in currently available experimental systems.

cond-mat.mes-hall↗

arXiv2010

Exciton-polariton mediated superconductivity

We revisit the exciton mechanism of superconductivity in the framework of microcavity physics, replacing virtual excitons as a binding agent of Cooper pairs by excitations of an exciton-polariton Bose-Einstein condensate. We consider a model microcavity where a quantum well with a two dimensional electron gas is sandwiched between two undoped quantum wells, where a polariton condensate is formed. We show that the critical temperature for superconductivity dramatically increases with the condensate population, opening a new route towards high temperature superconductivity.

cond-mat.supr-con↗

arXiv2010

Two-photon lasing by a single quantum dot in a high-Q microcavity

We investigate theoretically two-photon processes in a microcavity containing one quantum dot in the strong coupling regime. The cavity mode can be tuned to resonantly drive the two-photon transition between the ground and the biexciton states, while the exciton states are far-off resonance due to the biexciton binding energy. We study the steady state of the quantum dot and cavity field in presence of a continuous incoherent pumping. We identify the regime where the system acts as two-photon emitter and discuss the feasibility and performance of realistic single quantum dot devices for two-photon lasing.

cond-mat.mes-hall↗

arXiv2009

Optical Spectra of the Jaynes-Cummings Ladder

We explore how the Jaynes-Cummings ladder transpires in the emitted spectra of a two-level system in strong coupling with a single mode of light. We focus on the case of very strong coupling, that would be achieved with systems of exceedingly good quality (very long lifetimes for both the emitter and the cavity). We consider the incoherent regime of excitation, that is realized with semiconductors quantum dots in microcavities, and discuss how reasonable is the understanding of the systems in terms of transitions between dressed states of the Jaynes-Cummings Hamiltonian.

cond-mat.mes-hall↗

arXiv2009

Luminescence Spectra of Quantum Dots in Microcavities. II. Fermions

We discuss the luminescence spectra of coupled light-matter systems realized with semiconductor heterostructures in microcavities in the presence of a continuous, incoherent pumping, when the matter field is Fermionic. The linear regime--which has been the main topic of investigation both experimentally and theoretically--converges to the case of coupling to a Bosonic material field, and has been amply discussed in the first part of this work. We address here the nonlinear regime, and argue that, counter to intuition, it is better observed at low pumping intensities. We support our discussion with particular cases representative of, and beyond, the experimental state of the art. We explore the transition from the quantum to the classical regime, by decomposing the total spectrum into individual transitions between the dressed states of the light-matter coupling Hamiltonian, reducing the problem to the positions and broadenings of all possible transitions. As the system crosses to the classical limit, rich multiplet structures mapping the quantized energy levels melt and turn to cavity lasing and to an incoherent Mollow triplet in the direct exciton emission for very good structure. Less ideal figures of merit can still betray the quantum regime, with a proper balance of cavity versus electronic pumping.

cond-mat.mes-hall↗

arXiv2008

Luminescence Spectra of Quantum Dots in Microcavities. I. Bosons

We provide a unified theory of luminescence spectra of coupled light-matter systems realized with semiconductor heterostructures in microcavities, encompassing: i) the spontaneous emission case, where the system decays from a prepared (typically pure) initial state, and ii) luminescence in the presence of a continuous, incoherent pump. While the former case has been amply discussed in the literature (albeit mainly for the case of resonance), no consideration has been given to the influence of the incoherent pump. We show how, by provoking a self-consistent quantum state, the pump considerably alters the emission spectra, even at vanishing intensities. The main outcome of our analysis is to unambiguously identify strong-coupling in situations where it appears in disguise or only seems to appear. Here, we consider bosonic matter fields, in which case fully analytical solutions can be obtained. This describes the case of quantum wells or large quantum dots, or the limit of low excitation where the average populations remain much smaller than one.

cond-mat.mes-hall↗

arXiv2008

Strong-coupling of quantum dots in microcavities

We show that strong-coupling (SC) of light and matter as it is realized with quantum dots (QDs) in microcavities differs substantially from the paradigm of atoms in optical cavities. The type of pumping used in semiconductors yields new criteria to achieve SC, with situations where the pump hinders, or on the contrary, favours it. We analyze one of the seminal experimental observation of SC of a QD in a pillar microcavity [Reithmaier et al., Nature (2004)] as an illustration of our main statements.

cond-mat.mes-hall↗

arXiv2007

Electrostatic control of quantum dot entanglement induced by coupling to external reservoirs

We propose a quantum transport experiment to prepare and measure charge-entanglement between two electrostatically defined quantum dots. Coherent population trapping, as realized in cavity quantum electrodynamics, can be carried out by using a third quantum dot to play the role of the optical cavity. In our proposal, a pumping which is quantum mechanically indistinguishable for the quantum dots drives the system into a state with a high degree of entanglement. The whole effect can be switched on and off by means of a gate potential allowing both state preparation and entanglement detection by simply measuring the total current.

cond-mat.mes-hall↗

arXiv2005

Multiplets in Emission of Large Quantum Dots in Microcavities

We show theoretically that the emission spectrum of a single large quantum dot strongly coupled to a single photon mode in a microcavity can be qualitatively different from the spectrum obtained with an atom in a cavity. Instead of the well-known Mollow triplet we predict appearance of multiplets with the number of peaks a function of the quantum dot size and pumping intensity. The mutiplets can appear if the quantum dot is larger than the exciton Bohr radius, so that excitons are confined as whole particles in the dot. In this case the Pauli principle is relaxed and one can accommodate more than one exciton (but still a finite number) in a given quantum state.

cond-mat.mes-hall↗