61 research outputs found
Extraction of the beta-factor for single quantum dots coupled to a photonic crystal waveguide
We present measurements of the beta-factor, describing the coupling
efficiency of light emitted by single InAs/GaAs semiconductor quantum dots into
a photonic crystal waveguide mode. The beta-factor is evaluated by means of
time-resolved frequency-dependent photoluminescence spectroscopy. The emission
wavelength of single quantum dots is temperature tuned across the band edge of
a photonic crystal waveguide and the spontaneous emission rate is recorded.
Decay rates up to 5.7 ns^(-1), corresponding to a Purcell factor of 5.2, are
measured and beta-factors up to 85% are extracted. These results prove the
potential of photonic crystal waveguides in the realization of on-chip
single-photon sources.Comment: 3 pages, 3 figure
Non-exponential spontaneous emission dynamics for emitters in a time-dependent optical cavity
We have theoretically studied the effect of deterministic temporal control of
spontaneous emission in a dynamic optical microcavity. We propose a new
paradigm in light emission: we envision an ensemble of two-level emitters in an
environment where the local density of optical states is modified on a time
scale shorter than the decay time. A rate equation model is developed for the
excited state population of two-level emitters in a time-dependent environment
in the weak coupling regime in quantum electrodynamics. As a realistic
experimental system, we consider emitters in a semiconductor microcavity that
is switched by free-carrier excitation. We demonstrate that a short temporal
increase of the radiative decay rate depletes the excited state and drastically
increases the emission intensity during the switch time. The resulting
time-dependent spontaneous emission shows a distribution of photon arrival
times that strongly deviates from the usual exponential decay: A deterministic
burst of photons is spontaneously emitted during the switch event.Comment: 12 pages, 4 figure
Differential ultrafast all-optical switching of the resonances of a micropillar cavity
We perform frequency- and time-resolved all-optical switching of a GaAs-AlAs
micropillar cavity using an ultrafast pump-probe setup. The switching is
achieved by two-photon excitation of free carriers. We track the cavity
resonances in time with a high frequency resolution. The pillar modes exhibit
simultaneous frequency shifts, albeit with markedly different maximum switching
amplitudes and relaxation dynamics. These differences stem from the
non-uniformity of the free carrier density in the micropillar, and are well
understood by taking into account the spatial distribution of injected free
carriers, their spatial diffusion and surface recombination at micropillar
sidewalls.Comment: 4 pages, 3 figure
Nanomechanical single-photon routing
The merger between integrated photonics and quantum optics promises new
opportunities within photonic quantum technology with the very significant
progress on excellent photon-emitter interfaces and advanced optical circuits.
A key missing functionality is rapid circuitry reconfigurability that
ultimately does not introduce loss or emitter decoherence, and operating at a
speed matching the photon generation and quantum memory storage time of the
on-chip quantum emitter. This ambitious goal requires entirely new active
quantum-photonic devices by extending the traditional approaches to
reconfigurability. Here, by merging nano-optomechanics and deterministic
photon-emitter interfaces we demonstrate on-chip single-photon routing with low
loss, small device footprint, and an intrinsic time response approaching the
spin coherence time of solid-state quantum emitters. The device is an essential
building block for constructing advanced quantum photonic architectures
on-chip, towards, e.g., coherent multi-photon sources, deterministic
photon-photon quantum gates, quantum repeater nodes, or scalable quantum
networks.Comment: 7 pages, 3 figures, supplementary informatio
Statistical theory of a quantum emitter strongly coupled to Anderson-localized modes
A statistical theory of the coupling between a quantum emitter and
Anderson-localized cavity modes is presented based on a dyadic Green's function
formalism. The probability of achieving the strong light-matter coupling regime
is extracted for an experimentally realistic system composed of InAs quantum
dots embedded in a disordered photonic crystal waveguide. We demonstrate that
by engineering the relevant parameters that define the quality of light
confinement, i.e. the light localization length and the loss length, strong
coupling between a single quantum dot and an Anderson-localized cavity is
within experimental reach. As a consequence of disorder-induced light
confinement provides a novel platform for quantum electrodynamics experiments.Comment: 5 pages, 4 figure
Quantum optics with near lifetime-limited quantum-dot transitions in a nanophotonic waveguide
Establishing a highly efficient photon-emitter interface where the intrinsic
linewidth broadening is limited solely by spontaneous emission is a key step in
quantum optics. It opens a pathway to coherent light-matter interaction for,
e.g., the generation of highly indistinguishable photons, few-photon optical
nonlinearities, and photon-emitter quantum gates. However, residual broadening
mechanisms are ubiquitous and need to be combated. For solid-state emitters
charge and nuclear spin noise is of importance and the influence of photonic
nanostructures on the broadening has not been clarified. We present near
lifetime-limited linewidths for quantum dots embedded in nanophotonic
waveguides through a resonant transmission experiment. It is found that the
scattering of single photons from the quantum dot can be obtained with an
extinction of , which is limited by the coupling of the quantum
dot to the nanostructure rather than the linewidth broadening. This is obtained
by embedding the quantum dot in an electrically-contacted nanophotonic
membrane. A clear pathway to obtaining even larger single-photon extinction is
laid out, i.e., the approach enables a fully deterministic and coherent
photon-emitter interface in the solid state that is operated at optical
frequencies.Comment: 27 pages, 7 figure
- …