arXiv subjects

C. Anton

Publications and source records attributed to C. Anton.

8 recordsLinked to original sources

arXiv2021

Bright Polarized Single-Photon Source Based on a Linear Dipole

Semiconductor quantum dots in cavities are promising single-photon sources. Here, we present a path to deterministic operation, by harnessing the intrinsic linear dipole in a neutral quantum dot via phonon-assisted excitation. This enables emission of fully polarized single photons, with a measured degree of linear polarization up to 0.994 $\pm$ 0.007, and high population inversion -- 85\% as high as resonant excitation. We demonstrate a single-photon source with a polarized first lens brightness of 0.50 $\pm $ 0.01, a single-photon purity of 0.954 $\pm$ 0.001 and single-photon indistinguishability of 0.909 $\pm$ 0.004.

quant-ph↗

arXiv2020

Hong-Ou-Mandel Interference with Imperfect Single Photon Sources

Hong-Ou-Mandel interference is a cornerstone of optical quantum technologies. We explore both theoretically and experimentally how the nature of unwanted multi-photon components of single photon sources affect the interference visibility. We apply our approach to quantum dot single photon sources in order to access the mean wavepacket overlap of the single-photon component - an important metric to understand the limitations of current sources. We find that the impact of multi-photon events has thus far been underestimated, and that the effect of pure dephasing is even milder than previously expected.

quant-ph↗

arXiv2016

Scalable performance in solid-state single-photon sources

The desiderata for an ideal photon source are high brightness, high single-photon purity, and high indistinguishability. Defining brightness at the first collection lens, these properties have been simultaneously demonstrated with solid-state sources, however absolute source efficiencies remain close to the 1% level, and indistinguishability only demonstrated for photons emitted consecutively on the few nanosecond scale. Here we employ deterministic quantum dot-micropillar devices to demonstrate solid-state single-photon sources with scalable performance. In one device, an absolute brightness at the output of a single-mode fibre of 14% and purities of 97.1-99.0% are demonstrated. When non-resontantly excited, it emits a long stream of photons that exhibit indistinguishability up to 70%---above the classical limit of 50%---even after 33 consecutively emitted photons, a 400 ns separation between them. Resonant excitation in other devices results in near-optimal indistinguishability values: 96% at short timescales, remaining at 88% in timescales as large as 463 ns, after 39 emitted photons. The performance attained by our devices brings solid-state sources into a regime suitable for scalable implementations.

quant-ph↗

arXiv2015

Near optimal single photon sources in the solid state

Single-photons are key elements of many future quantum technologies, be it for the realisation of large-scale quantum communication networks for quantum simulation of chemical and physical processes or for connecting quantum memories in a quantum computer. Scaling quantum technologies will thus require efficient, on-demand, sources of highly indistinguishable single-photons. Semiconductor quantum dots inserted in photonic structures are ultrabright single photon sources, but the photon indistinguishability is limited by charge noise induced by nearby surfaces. The current state of the art for indistinguishability are parametric down conversion single-photon sources, but they intrinsically generate multiphoton events and hence must be operated at very low brightness to maintain high single photon purity. To date, no technology has proven to be capable of providing a source that simultaneously generates near-unity indistinguishability and pure single photons with high brightness. Here, we report on such devices made of quantum dots in electrically controlled cavity structures. We demonstrate on-demand, bright and ultra-pure single photon generation. Application of an electrical bias on deterministically fabricated devices is shown to fully cancel charge noise effects. Under resonant excitation, an indistinguishability of $0.9956\pm0.0045$ is evidenced with a $g^{2}(0)=0.0028\pm0.0012$. The photon extraction of $65%$ and measured brightness of $0.154\pm0.015$ make this source $20$ times brighter than any source of equal quality. This new generation of sources open the way to a new level of complexity and scalability in optical quantum manipulation.

quant-ph↗

arXiv2013

Motion of spin polariton bullets in semiconductor microcavities

The dynamics of optical switching in semiconductor microcavities in the strong coupling regime is studied using time- and spatially-resolved spectroscopy. The switching is triggered by polarised short pulses which create spin bullets of high polariton density. The spin packets travel with speeds of the order of 106 m/s due to the ballistic propagation and drift of exciton-polaritons from high to low density areas. The speed is controlled by the angle of incidence of the excitation beams, which changes the polariton group velocity.

cond-mat.mes-hall↗

arXiv2012

Dynamics of a polariton condensate transistor switch

We present a time-resolved study of the logical operation of a polariton condensate transistor switch. Creating a polariton condensate (source) in a GaAs ridge-shaped microcavity with a non-resonant pulsed laser beam, the polariton propagation towards a collector, at the ridge edge, is controlled by a second weak pulse (gate), located between the source and the collector. The experimental results are interpreted in the light of simulations based on the generalized Gross-Pitaevskii equation, including incoherent pumping, decay and energy relaxation within the condensate.

cond-mat.mes-hall↗

arXiv2012

Role of supercurrents on vortices formation in polariton condensates

Observation of quantized vortices in non-equilibrium polariton condensates has been reported either by spontaneous formation and pinning in the presence of disorder or by imprinting them onto the signal or idler of an optical parametric oscillator (OPO). Here, we report a detailed analysis of the creation and annihilation of polariton vortex-antivortex pairs in the signal state of a polariton OPO by means of a short optical Gaussian pulse at a certain finite pump wave-vector. A time-resolved, interferometric analysis of the emission allows us to extract the phase of the perturbed condensate and to reveal the dynamics of the supercurrents created by the pulsed probe. This flow is responsible for the appearance of the topological defects when counter-propagating to the underlying currents of the OPO signal.

cond-mat.mes-hall↗

arXiv2011

Onset and dynamics of vortex-antivortex pairs in polariton OPO superfluids

We study, both theoretically and experimentally, the occurrence of topological defects in polariton superfluids in the optical parametric oscillator (OPO) regime. We explain in terms of local supercurrents the deterministic behaviour of both onset and dynamics of spontaneous vortex-antivortex pairs generated by perturbing the system with a pulsed probe. Using a generalised Gross-Pitaevskii equation, including photonic disorder, pumping and decay, we elucidate the reason why topological defects form in couples and can be detected by direct visualizations in multi-shot OPO experiments.

cond-mat.mes-hall↗