87 research outputs found
Accurate measurement of a 96% input coupling into a cavity using polarization tomography
Pillar microcavities are excellent light-matter interfaces providing an
electromagnetic confinement in small mode volumes with high quality factors.
They also allow the efficient injection and extraction of photons, into and
from the cavity, with potentially near-unity input and output-coupling
efficiencies. Optimizing the input and output coupling is essential, in
particular, in the development of solid-state quantum networks where artificial
atoms are manipulated with single incoming photons. Here we propose a technique
to accurately measure input and output coupling efficiencies using polarization
tomography of the light reflected by the cavity. We use the residual
birefringence of pillar microcavities to distinguish the light coupled to the
cavity from the uncoupled light: the former participates to rotating the
polarization of the reflected beam, while the latter decreases the polarization
purity. Applying this technique to a micropillar cavity, we measure a output coupling and a input coupling with unprecedented
precision.Comment: 6 pages, 3 figure
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
Hybrid organic-inorganic polariton laser
Organic materials exhibit exceptional room temperature light emitting characteristics and enormous exciton oscillator strength, however, their low charge carrier mobility prevent their use in high-performance applications such as electrically pumped lasers. In this context, ultralow threshold polariton lasers, whose operation relies on Bose-Einstein condensation of polaritons - part-light part-matter quasiparticles, are highly advantageous since the requirement for high carrier injection no longer holds. Polariton lasers have been successfully implemented using inorganic materials owing to their excellent electrical properties, however, in most cases their relatively small exciton binding energies limit their operation temperature. It has been suggested that combining organic and inorganic semiconductors in a hybrid microcavity, exploiting resonant interactions between these materials would permit to dramatically enhance optical nonlinearities and operation temperature. Here, we obtain cavity mediated hybridization of GaAs and J-aggregate excitons in the strong coupling regime under electrical injection of carriers as well as polariton lasing up to 200 K under non-resonant optical pumping. Our demonstration paves the way towards realization of hybrid organic-inorganic microcavities which utilise the organic component for sustaining high temperature polariton condensation and efficient electrical injection through inorganic structure
Deterministic assembly of a charged quantum dot-micropillar cavity device
Developing future quantum communication may rely on the ability to engineer
cavity-mediated interactions between photons and solid-state artificial atoms,
in a deterministic way. Here, we report a set of technological and experimental
developments for the deterministic coupling between the optical mode of a
micropillar cavity and a quantum dot trion transition. We first identify a
charged transition through in-plane magnetic field spectroscopy, and then tune
the optical cavity mode to its energy via in-situ lithography. In addition, we
design an asymmetric tunneling barrier to allow the optical trapping of the
charge, assisted by a quasi-resonant pumping scheme, in order to control its
occupation probability. We evaluate the generation of a positively-charged
quantum dot through second order auto-correlation measurements of its resonance
fluorescence, and the quality of light-matter interaction for these spin-photon
interfaces is assessed by measuring the performance of the device as a
single-photon source.Comment: 9 pages, 7 figure
Probing the dynamics and coherence of a semiconductor hole spin via acoustic phonon-assisted excitation
Spins in semiconductor quantum dots are promising local quantum memories to
generate polarization-encoded photonic cluster states, as proposed in the
pioneering Rudolph-Lindner scheme [1]. However, harnessing the polarization
degree of freedom of the optical transitions is hindered by resonant excitation
schemes that are widely used to obtain high photon indistinguishability. Here
we show that acoustic phonon-assisted excitation, a scheme that preserves high
indistinguishability, also allows to fully exploit the polarization selective
optical transitions to initialise and measure single spin states. We access the
coherence of hole spin systems in a low transverse magnetic field and directly
monitor the spin Larmor precession both during the radiative emission process
of an excited state or in the quantum dot ground state. We report a spin state
detection fidelity of granted by the optical selection rules
and a ~ns hole spin coherence time, demonstrating the potential of this
scheme and system to generate linear cluster states with a dozen of photonsComment: 3 figure
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