8 research outputs found
Observation of large spontaneous emission rate enhancement of quantum dots in a broken-symmetry slow-light waveguide
Quantum states of light and matter can be manipulated on the nanoscale to
provide a technological resource for aiding the implementation of scalable
photonic quantum technologies [1-3]. Experimental progress relies on the
quality and efficiency of the coupling between photons and internal states of
quantum emitters [4-6]. Here we demonstrate a nanophotonic waveguide platform
with embedded quantum dots (QDs) that enables both Purcell-enhanced emission
and strong chiral coupling. The design uses slow-light effects in a glide-plane
photonic crystal waveguide with QD tuning to match the emission frequency to
the slow-light region. Simulations were used to map the chirality and Purcell
enhancement depending on the position of a dipole emitter relative to the air
holes. The highest Purcell factors and chirality occur in separate regions, but
there is still a significant area where high values of both can be obtained.
Based on this, we first demonstrate a record large radiative decay rate of 17
ns^-1 (60 ps lifetime) corresponding to a 20 fold Purcell enhancement. This was
achieved by electric-field tuning of the QD to the slow-light region and
quasi-resonant phonon-sideband excitation. We then demonstrate a 5 fold Purcell
enhancement for a dot with high degree of chiral coupling to waveguide modes,
substantially surpassing all previous measurements. Together these demonstrate
the excellent prospects for using QDs in scalable implementations of on-chip
spin-photonics relying on chiral quantum optics.Comment: 15 pages, 4 figures, 1 table. Supporting information is available
upon request to the corresponding autho
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 behaviour 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 sub-natural linewidth cannot
simultaneously be observed, providing new insight into the nature of coherent
scattering.Comment: Main manuscript 7 pages with 4 figures, supplementary material of 4
page
Purcell-Enhanced Single Photons at Telecom Wavelengths from a Quantum Dot in a Photonic Crystal Cavity
Quantum dots are promising candidates for telecom single photon sources due
to their tunable emission across the different low-loss telecommunications
bands, making them compatible with existing fiber networks. Their suitability
for integration into photonic structures allows for enhanced brightness through
the Purcell effect, supporting efficient quantum communication technologies.
Our work focuses on InAs/InP QDs created via droplet epitaxy MOVPE to operate
within the telecoms C-band. We observe a short radiative lifetime of 340 ps,
arising from a Purcell factor of 5, owing to interaction of the QD within a
low-mode-volume photonic crystal cavity. Through in-situ control of the sample
temperature, we show both temperature tuning of the QD's emission wavelength
and a preserved single photon emission purity at temperatures up to 25K. These
findings suggest the viability of QD-based, cryogen-free, C-band single photon
sources, supporting applicability in quantum communication technologies
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
Observation of large spontaneous emission rate enhancement of quantum dots in a broken-symmetry slow-light waveguide
AbstractQuantum states of light and matter can be manipulated on the nanoscale to provide a technological resource for aiding the implementation of scalable photonic quantum technologies. Experimental progress relies on the quality and efficiency of the coupling between photons and internal spin states of quantum emitters. Here we demonstrate a nanophotonic waveguide platform with embedded quantum dots (QDs) that enables both Purcell-enhanced emission and strong chiral coupling. The design uses slow-light effects in a glide-plane photonic crystal waveguide with QD tuning to match the emission frequency to the slow-light region. Simulations were used to map the chirality and Purcell enhancement depending on the position of a dipole emitter relative to the air holes. The highest Purcell factors and chirality occur in separate regions, but there is still a significant area where high values of both can be obtained. Based on this, we first demonstrate a record large radiative decay rate of 17 ± 2 ns−1 (60 ± 6 ps lifetime) corresponding to a 20 ± 2 fold Purcell enhancement. This was achieved by electric-field tuning of the QD to the slow-light region and quasi-resonant phonon-side band excitation. We then demonstrate a 5 ± 1 fold Purcell enhancement for a dot with high degree of chiral coupling to waveguide modes, substantially surpassing all previous measurements. Together these demonstrate the excellent prospects for using QDs in scalable implementations of on-chip spin-photonics relying on chiral quantum optics.</jats:p