15 research outputs found
Cavity-Enhanced Two-Photon Interference using Remote Quantum Dot Sources
Quantum dots in cavities have been shown to be very bright sources of
indistinguishable single photons. Yet the quantum interference between two
bright quantum dot sources, a critical step for photon based quantum
computation, has never been investigated. Here we report on such a measurement,
taking advantage of a deterministic fabrication of the devices. We show that
cavity quantum electrodynamics can efficiently improve the quantum interference
between remote quantum dot sources: poorly indistinguishable photons can still
interfere with good contrast with high quality photons emitted by a source in
the strong Purcell regime. Our measurements and calculations show that cavity
quantum electrodynamics is a powerful tool for interconnecting several devices.Comment: 5 pages, 4 figures (Supp. Mat. attached
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
is evidenced with a . The photon
extraction of and measured brightness of make this source
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
Remote ischaemic conditioning: defining critical criteria for success—report from the 11th Hatter Cardiovascular Workshop
Abstract: The Hatter Cardiovascular Institute biennial workshop, originally scheduled for April 2020 but postponed for 2 years due to the Covid pandemic, was organised to debate and discuss the future of Remote Ischaemic Conditioning (RIC). This evolved from the large multicentre CONDI-2–ERIC–PPCI outcome study which demonstrated no additional benefit when using RIC in the setting of ST-elevation myocardial infarction (STEMI). The workshop discussed how conditioning has led to a significant and fundamental understanding of the mechanisms preventing cell death following ischaemia and reperfusion, and the key target cyto-protective pathways recruited by protective interventions, such as RIC. However, the obvious need to translate this protection to the clinical setting has not materialised largely due to the disconnect between preclinical and clinical studies. Discussion points included how to adapt preclinical animal studies to mirror the patient presenting with an acute myocardial infarction, as well as how to refine patient selection in clinical studies to account for co-morbidities and ongoing therapy. These latter scenarios can modify cytoprotective signalling and need to be taken into account to allow for a more robust outcome when powered appropriately. The workshop also discussed the potential for RIC in other disease settings including ischaemic stroke, cardio-oncology and COVID-19. The workshop, therefore, put forward specific classifications which could help identify so-called responders vs. non-responders in both the preclinical and clinical settings
Reducing Phonon-Induced Decoherence in Solid-State Single-Photon Sources with Cavity Quantum Electrodynamics
International audienc
Reducing Phonon-Induced Decoherence in Solid-State Single-Photon Sources with Cavity Quantum Electrodynamics
Solid-state emitters are excellent candidates for developing integrated
sources of single photons. Yet, phonons degrade the photon indistinguishability
both through pure dephasing of the zero-phonon line and through phonon-assisted
emission. Here, we study theoretically and experimentally the
indistinguishability of photons emitted by a semiconductor quantum dot in a
microcavity as a function of temperature. We show that a large coupling to a
high quality factor cavity can simultaneously reduce the effect of both
phonon-induced sources of decoherence. It first limits the effect of pure
dephasing on the zero phonon line with indistinguishabilities above up
to K. Moreover, it efficiently redirects the phonon sidebands into the
zero-phonon line and brings the indistinguishability of the full emission
spectrum from (resp. ) without cavity effect to more than
(resp. ) at K (resp. K). We provide guidelines for optimal
cavity designs that further minimize the phonon-induced decoherence.Comment: (6 pages, 3 figures) + (11 pages, 10 figures in Supplemental
Material
Fiber-integrated microcavities for efficient generation of coherent acoustic phonons
International audienceCoherent phonon generation by optical pump-probe experiments has enabled the study of acoustic properties at the nanoscale in planar heterostructures, plasmonic resonators, micropillars and nanowires. Focalizing both pump and probe on the same spot of the sample is a critical part of pumpprobe experiments. This is particularly relevant in the case of small objects. The main practical challenges for the actual implementation of this technique are: stability of the spatio-temporal overlap, reproducibility of the focalization and optical mode matching conditions. In this work, we solve these three challenges for the case of planar and micropillar optophononic cavities. We integrate the studied samples to single mode fibers lifting the need for focusing optics to excite and detect coherent acoustic phonons. The resulting excellent reflectivity contrast of at least 66% achieved in our samples allows us to observe stable coherent phonon signals over at least a full day and signals at extremely low excitation powers of 1µW. The monolithic sample structure is transportable and could provide a means to perform reproducible plug-and-play experiments