16 research outputs found
Frequency tuning of a triply-resonant whispering-gallery mode resonator to MHz wide transitions for proposed quantum repeater schemes
Quantum repeaters rely on an interfacing of flying qubits with quantum
memories. The most common implementations include a narrowband single photon
matched in bandwidth and central frequency to an atomic system. Previously, we
demonstrated the compatibility of our versatile source of heralded single
photons, which is based on parametric down-conversion in a triply-resonant
whispering-gallery mode resonator, with alkaline transitions [Schunk et al.,
Optica 2, 773 (2015)]. In this paper, we analyze our source in terms of phase
matching, available wavelength-tuning mechanisms, and applications to
narrow-band atomic systems. We resonantly address the D1 transitions of cesium
and rubidium with this optical parametric oscillator pumped above its
oscillation threshold. Below threshold, the efficient coupling of single
photons to atomic transitions heralded by single telecom-band photons is
demonstrated. Finally, we present an accurate analytical description of our
observations. Providing the demonstrated flexibility in connecting various
atomic transitions with telecom wavelengths, we show a promising approach to
realize an essential building block for quantum repeaters.Comment: 18 pages, 14 figure
Squeezed vacuum states from a whispering gallery mode resonator
Squeezed vacuum states enable optical measurements below the quantum limit
and hence are a valuable resource for applications in quantum metrology and
also quantum communication. However, most available sources require high pump
powers in the milliwatt range and large setups, which hinders real world
applications. Furthermore, degenerate operation of such systems presents a
challenge. Here, we use a compact crystalline whispering gallery mode resonator
made of lithium niobate as a degenerate parametric oscillator. We demonstrate
about 1.4 dB noise reduction below the shot noise level for only 300
of pump power in degenerate single mode operation. Furthermore,
we report a record pump threshold as low as 1.35 . Our results
show that the whispering gallery based approach presents a promising platform
for a compact and efficient source for nonclassical light.Comment: 2019 Optical Society of America. Users may use, reuse,
and build upon the article, or use the article for text or data mining, so
long as such uses are for non-commercial purposes and appropriate attribution
is maintained. All other rights are reserve
Nonlinear power dependence of the spectral properties of an optical parametric oscillator below threshold in the quantum regime
Photon pairs and heralded single photons, obtained from cavity-assisted
parametric down-conversion (PDC), play an important role in quantum
communications and technology. This motivated a thorough study of the spectral
and temporal properties of parametric light, both above the Optical Parametric
Oscillator (OPO) threshold, where the semiclassical approach is justified, and
deeply below it, where the linear cavity approximation is applicable. The
pursuit of a higher two-photon emission rate leads into an interesting
intermediate regime where the OPO still operates considerably below the
threshold but the nonlinear cavity phenomena cannot be neglected anymore. Here,
we investigate this intermediate regime and show that the spectral and temporal
properties of the photon pairs, as well as their emission rate, may
significantly differ from the widely accepted linear model. The observed
phenomena include frequency pulling and broadening in the temporal correlation
for the down-converted optical fields. These factors need to be taken into
account when devising practical applications of the high-rate cavity-assisted
SPDC sources
Entangled-photon Fourier optics
Entangled photons, generated by spontaneous parametric down-conversion from a
second-order nonlinear crystal, present a rich potential for imaging and
image-processing applications. Since this source is an example of a three-wave
mixing process, there is more flexibility in the choices of illumination and
detection wavelengths and in the placement of object(s) to be imaged. Moreover,
this source is entangled, a fact that allows for imaging configurations and
capabilities that cannot be achieved using classical sources of light. In this
paper we examine a number of imaging and image-processing configurations that
can be realized using this source. The formalism that we utilize facilitates
the determination of the dependence of imaging resolution on the physical
parameters of the optical arrangement.Comment: 41 pages, 12 figures, accepted for publication in J. Opt. Soc. Am.
Role of entanglement in two-photon imaging
The use of entangled photons in an imaging system can exhibit effects that
cannot be mimicked by any other two-photon source, whatever the strength of the
correlations between the two photons. We consider a two-photon imaging system
in which one photon is used to probe a remote (transmissive or scattering)
object, while the other serves as a reference. We discuss the role of
entanglement versus correlation in such a setting, and demonstrate that
entanglement is a prerequisite for achieving distributed quantum imaging.Comment: 15 pages, 2 figure
The Scientific Measurement System of the Gravity Recovery and Interior Laboratory (GRAIL) Mission
The Gravity Recovery and Interior Laboratory (GRAIL) mission to the Moon utilized an integrated scientific measurement system comprised of flight, ground, mission, and data system elements in order to meet the end-to-end performance required to achieve its scientific objectives. Modeling and simulation efforts were carried out early in the mission that influenced and optimized the design, implementation, and testing of these elements. Because the two prime scientific observables, range between the two spacecraft and range rates between each spacecraft and ground stations, can be affected by the performance of any element of the mission, we treated every element as part of an extended science instrument, a science system. All simulations and modeling took into account the design and configuration of each element to compute the expected performance and error budgets. In the process, scientific requirements were converted to engineering specifications that became the primary drivers for development and testing. Extensive simulations demonstrated that the scientific objectives could in most cases be met with significant margin. Errors are grouped into dynamic or kinematic sources and the largest source of non-gravitational error comes from spacecraft thermal radiation. With all error models included, the baseline solution shows that estimation of the lunar gravity field is robust against both dynamic and kinematic errors and a nominal field of degree 300 or better could be achieved according to the scaled Kaula rule for the Moon. The core signature is more sensitive to modeling errors and can be recovered with a small margin
The deep space quantum link: prospective fundamental physics experiments using long-baseline quantum optics
The National Aeronautics and Space Administration's Deep Space Quantum Link mission concept enables a unique set of science experiments by establishing robust quantum optical links across extremely long baselines. Potential mission configurations include establishing a quantum link between the Lunar Gateway moon-orbiting space station and nodes on or near the Earth. This publication summarizes the principal experimental goals of the Deep Space Quantum Link. These goals, identified through a multi-year design study conducted by the authors, include long-range teleportation, tests of gravitational coupling to quantum states, and advanced tests of quantum nonlocality
Control system of temperature of locomotives traction frequency converters
The features of the control systems of temperature of the traction frequency converters consisted of rectifier, capacitor and voltage source inverter for traction rolling stock are discussed. The induction motor is considered as a load for traction frequency converter. The dependence of the number of thermal cycles from semiconductor junction temperature fluctuations before the failure of the semiconductor device are shown. The topology and operation principle of automatic temperature control system of voltage source inverter semiconductor devices of traction frequency converter are developed and described. The system is based on air forced cooling with the use of fan or blower as an executive regulation device. The main feature of the proposed system is the additional reference of switching frequency that allows to reduce the semiconductor temperature fluctuations. The elements of switching frequency control loop are chosen and evaluated, the recommendations on practical implementations are given. Simulation of automatic temperature control system in Matlab with both references of semiconductor junction temperature and its fluctuation was carried out with all essential nonlinearities of induction motors and semiconductor devices taken into account. Results of simulation are included and discussed