Photon Statistics of Filtered Resonance Fluorescence.

Spectral filtering of resonance fluorescence is widely employed to improve single photon purity and indistinguishability by removing unwanted backgrounds. For filter bandwidths approaching the emitter linewidth, complex behavior is predicted due to preferential transmission of components with differing photon statistics. We probe this regime using a Purcell-enhanced quantum dot in both weak and strong excitation limits, finding excellent agreement with an extended sensor theory model. By changing only the filter width, the photon statistics can be transformed between antibunched, bunched, or Poissonian. Our results verify that strong antibunching and a subnatural linewidth cannot simultaneously be observed, providing new insight into the nature of coherent scattering.

Light Scattering from Solid-State Quantum Emitters: Beyond the Atomic Picture.

Coherent scattering of light by a single quantum emitter is a fundamental process at the heart of many proposed quantum technologies. Unlike atomic systems, solid-state emitters couple to their host lattice by phonons. Using a quantum dot in an optical nanocavity, we resolve these interactions in both time and frequency domains, going beyond the atomic picture to develop a comprehensive model of light scattering from solid-state emitters. We find that even in the presence of a low-Q cavity with high Purcell enhancement, phonon coupling leads to a sideband that is completely insensitive to excitation conditions and to a nonmonotonic relationship between laser detuning and coherent fraction, both of which are major deviations from atomlike behavior.

High Purcell factor generation of indistinguishable on-chip single photons.

On-chip single-photon sources are key components for integrated photonic quantum technologies. Semiconductor quantum dots can exhibit near-ideal single-photon emission, but this can be significantly degraded in on-chip geometries owing to nearby etched surfaces. A long-proposed solution to improve the indistinguishablility is to use the Purcell effect to reduce the radiative lifetime. However, until now only modest Purcell enhancements have been observed. Here we use pulsed resonant excitation to eliminate slow relaxation paths, revealing a highly Purcell-shortened radiative lifetime (22.7 ps) in a waveguide-coupled quantum dot-photonic crystal cavity system. This leads to near-lifetime-limited single-photon emission that retains high indistinguishablility (93.9%) on a timescale in which 20 photons may be emitted. Nearly background-free pulsed resonance fluorescence is achieved under π-pulse excitation, enabling demonstration of an on-chip, on-demand single-photon source with very high potential repetition rates.

Dilute nitride and GaAs n-i-p-i solar cells.

We demonstrate for the first time the operation of GaInNAs and GaAs n-i-p-i doping solar cells with ion-implanted selective contacts. Multiple layers of alternate doping are grown by molecular beam epitaxy to form the n-i-p-i structure. After growth, vertical selective contacts are fabricated by Mg and Si ion implantation, followed by rapid thermal annealing treatment and fabrication into circular mesa cells. As means of characterisation, spectral response and illuminated current-voltage (I-V) were measured on the samples. The spectral response suggests that all horizontal layers are able to contribute to the photocurrent. Performance of the devices is discussed with interest in the n-i-p-i structure as a possible design for the GaInP/GaAs/GaInNAs tandem solar cell.