115 research outputs found
Single Photon Source with Individualized Single Photon Certifications
As currently implemented, single-photon sources cannot be made to produce
single photons with high probability, while simultaneously suppressing the
probability of yielding two or more photons. Because of this, single photon
sources cannot really produce single photons on demand. We describe a
multiplexed system that allows the probabilities of producing one and more
photons to be adjusted independently, enabling a much better approximation of a
source of single photons on demand. The scheme uses a heralded photon source
based on parametric downconversion, but by effectively breaking the trigger
detector area into multiple regions, we are able to extract more information
about a heralded photon than is possible with a conventional arrangement. This
scheme allows photons to be produced along with a quantitative
``certification'' that they are single photons. Some of the single-photon
certifications can be significantly better than what is possible with
conventional downconversion sources (using a unified trigger detector region),
as well as being better than faint laser sources. With such a source of more
tightly certified single photons, it should be possible to improve the maximum
secure bit rate possible over a quantum cryptographic link. We present an
analysis of the relative merits of this method over the conventional
arrangement.Comment: 11 pages, 5 figures, SPIE Free-Space Laser Communication and Laser
Imaging II. To appear in the proceeding of SPIE Free-Space Laser
Communication and Laser Imaging II, vol 482
Optimizing single-photon-source heralding efficiency at 1550 nm using periodically poled lithium niobate
We explore the feasibility of using high conversion-efficiency
periodically-poled crystals to produce photon pairs for photon-counting
detector calibrations at 1550 nm. The goal is the development of an appropriate
parametric down-conversion (PDC) source at telecom wavelengths meeting the
requirements of high-efficiency pair production and collection in single
spectral and spatial modes (single-mode fibers). We propose a protocol to
optimize the photon collection, noise levels and the uncertainty evaluation.
This study ties together the results of our efforts to model the single-mode
heralding efficiency of a two-photon PDC source and to estimate the heralding
uncertainty of such a source.Comment: 14 pages, 2 tables and 3 figures, final version accepted by
Metrologi
Topologically Robust Transport of Photons in a Synthetic Gauge Field
Electronic transport in low dimensions through a disordered medium leads to
localization. The addition of gauge fields to disordered media leads to
fundamental changes in the transport properties. For example, chiral edge
states can emerge in two-dimensional systems with a perpendicular magnetic
field. Here, we implement a "synthetic'' gauge field for photons using
silicon-on-insulator technology. By determining the distribution of transport
properties, we confirm the localized transport in the bulk and the suppression
of localization in edge states, using the "gold standard'' for localization
studies. Our system provides a new platform to investigate transport properties
in the presence of synthetic gauge fields, which is important both from the
fundamental perspective of studying photonic transport and for applications in
classical and quantum information processing.Comment: 4.5 pages, 3 figures and supplementary materia
Reduced Deadtime and Higher Rate Photon-Counting Detection using a Multiplexed Detector Array
We present a scheme for a photon-counting detection system that can be
operated at incident photon rates higher than otherwise possible by suppressing
the effects of detector deadtime. The method uses an array of N detectors and a
1-by-N optical switch with a control circuit to direct input light to live
detectors. Our calculations and models highlight the advantages of the
technique. In particular, using this scheme, a group of N detectors provides an
improvement in operation rate that can exceed the improvement that would be
obtained by a single detector with deadtime reduced by 1/N, even if it were
feasible to produce a single detector with such a large improvement in
deadtime. We model the system for continuous and pulsed light sources, both of
which are important for quantum metrology and quantum key distribution
applications.Comment: 6 figure
Experimental realization of a low-noise heralded single photon source
We present a heralded single-photon source with a much lower level of
unwanted background photons in the output channel by using the herald photon to
control a shutter in the heralded channel. The shutter is implemented using a
simple field programable gate array controlled optical switch.Comment: 4 pages, 5 figure
An extremely low-noise heralded single-photon source: a breakthrough for quantum technologies
Low noise single-photon sources are a critical element for quantum
technologies. We present a heralded single-photon source with an extremely low
level of residual background photons, by implementing low-jitter detectors and
electronics and a fast custom-made pulse generator controlling an optical
shutter (a LiNbO3 waveguide optical switch) on the output of the source. This
source has a second-order autocorrelation g^{(2)}(0)=0.005(7), and an "Output
Noise Factor" (defined as the ratio of the number of noise photons to total
photons at the source output channel) of 0.25(1)%. These are the best
performance characteristics reported to date
High coherence photon pair source for quantum communication
This paper reports a novel single mode source of narrow-band entangled photon
pairs at telecom wavelengths under continuous wave excitation, based on
parametric down conversion. For only 7 mW of pump power it has a created
spectral radiance of 0.08 pairs per coherence length and a bandwidth of 10 pm
(1.2 GHz). The effectively emitted spectral brightness reaches 3.9*10^5 pairs
/(s pm). Furthermore, when combined with low jitter single photon detectors,
such sources allow for the implementation of quantum communication protocols
without any active synchronization or path length stabilization. A HOM-Dip with
photons from two autonomous CW sources has been realized demonstrating the
setup's stability and performance.Comment: 12 pages, 4 figure
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