82 research outputs found
An optical heterodyne densitometer
Researchers are developing an optical heterodyne densitometer with the potential to measure optical density over an unprecedented dynamic range with high accuracy and sensitivity. This device uses a Mach-Zender interferometer configuration with heterodyne detection to make direct comparisons between optical and RF attenuators. Researchers expect to attain measurements of filter transmittance down to 10 to the minus 12th power with better than 1 percent uncertainty. In addition, they intend to extend the technique to the problem of measuring low levels of light scattering from reflective and transmissive optics
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
Enhancing image contrast using coherent states and photon number resolving detectors
We experimentally map the transverse profile of diffraction-limited beams
using photon-number-resolving detectors. We observe strong compression of
diffracted beam profiles for high detected photon number. This effect leads to
higher contrast than a conventional irradiance profile between two Airy
disk-beams separated by the Rayleigh criterion.Comment: 7 pages, 3 figures, accepted for publication in Optics Expres
Properties of entangled photon pairs generated in one-dimensional nonlinear photonic-band-gap structures
We have developed a rigorous quantum model of spontaneous parametric
down-conversion in a nonlinear 1D photonic-band-gap structure based upon
expansion of the field into monochromatic plane waves. The model provides a
two-photon amplitude of a created photon pair. The spectra of the signal and
idler fields, their intensity profiles in the time domain, as well as the
coincidence-count interference pattern in a Hong-Ou-Mandel interferometer are
determined both for cw and pulsed pumping regimes in terms of the two-photon
amplitude. A broad range of parameters characterizing the emitted
down-converted fields can be used. As an example, a structure composed of 49
layers of GaN/AlN is analyzed as a suitable source of photon pairs having high
efficiency.Comment: 14 pages, 23 figure
Impact of the Court of International Trade on the Department of Commerce’s Administration of the Antidumping and Countervailing Duty Laws
Experimental joint signal-idler quasi-distributions and photon-number statistics for mesoscopic twin beams
Joint signal-idler photoelectron distributions of twin beams containing
several tens of photons per mode have been measured recently. Exploiting a
microscopic quantum theory for joint quasi-distributions in parametric
down-conversion developed earlier we characterize properties of twin beams in
terms of quasi-distributions using experimental data. Negative values as well
as oscillating behaviour in quantum region are characteristic for the
subsequently determined joint signal-idler quasi-distributions of integrated
intensities. Also the conditional and difference photon-number distributions
are shown to be sub-Poissonian and sub-shot-noise, respectively.Comment: 7 pages, 6 figure
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
Effect of hyperfine structure on atomic frequency combs in Pr:YSO
Quantum memory will be a key component in future quantum networks, and atomic
frequency combs (AFCs) in rare-earth-doped crystals are one promising platform
for realizing this technology. We theoretically and experimentally investigate
the formation of AFCs in Pr3+:Y2SiO5, with an overall bandwidth of 120 MHz and
tooth spacing ranging from 0.1 MHz to 20 MHz, showing agreement between our
calculations and measurements. We observe that the echo efficiency depends
crucially on the AFC tooth spacing. Our results suggest approaches to
developing a high-efficiency AFC quantum memory.Comment: 20 pages, 7 figure
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