1,430 research outputs found
Nonclassical radiation from diamond nanocrystals
The quantum properties of the fluorescence light emitted by diamond
nanocrystals containing a single nitrogen-vacancy (NV) colored center is
investigated. We have observed photon antibunching with very low background
light. This system is therefore a very good candidate for the production of
single photon on demand. In addition, we have measured larger NV center
lifetime in nanocrystals than in the bulk, in good agreement with a simple
quantum electrodynamical model.Comment: 8 pages, 5 figures, revised version, to appear in PR
Complete amino acid sequence of a human platelet proteoglycan
AbstractThe primary structure of a human platelet proteoglycan (P.PG) core was established by a combination of amino acid sequence analysis and cDNA cloning. The deduced 131 amino acid long protein contains eight Ser-Gly repeats. The significance of homologies observed between P.PG and promyelocytic leukemia cell line proteoglycans is discussed
Single photon quantum cryptography
We report the full implementation of a quantum cryptography protocol using a
stream of single photon pulses generated by a stable and efficient source
operating at room temperature. The single photon pulses are emitted on demand
by a single nitrogen-vacancy (NV) color center in a diamond nanocrystal. The
quantum bit error rate is less that 4.6% and the secure bit rate is 9500
bits/s. The overall performances of our system reaches a domain where single
photons have a measurable advantage over an equivalent system based on
attenuated light pulses.Comment: 4 pages, 3 figure
Photon antibunching in the fluorescence of individual color centers in diamond
We have observed photon antibunching in the fluorescence light emitted from a
single N-V center in diamond at room temperature. The possibility of generating
triggerable single photons with such a solide state system is discussedComment: 4 pages, 4 figure
Homodyne estimation of Gaussian quantum discord
We address the experimental estimation of Gaussian quantum discord for
two-mode squeezed thermal state, and demonstrate a measurement scheme based on
a pair of homodyne detectors assisted by Bayesian analysis which provides
nearly optimal estimation for small value of discord. Besides, though homodyne
detection is not optimal for Gaussian discord, the noise ratio to the ultimate
quantum limit, as dictacted by the quantum Cramer-Rao bound, is limited to
about 10 dB.Comment: 5+3 pages, 3 figures, published versio
Improving the maximum transmission distance of continuous-variable quantum key distribution using a noiseless amplifier
We show that the maximum transmission distance of continuous-variable quantum
key distribution in presence of a Gaussian noisy lossy channel can be
arbitrarily increased using a linear noiseless amplifier. We explicitly
consider a protocol using amplitude and phase modulated coherent states with
reverse reconciliation. We find that a noiseless amplifier with amplitude gain
g can increase the maximum admissible losses by a factor 1/g^2.Comment: 8 pages, 6 figure
Nanoscale heat flux between nanoporous materials
International audienceBy combining stochastic electrodynamics and the Maxwell-Garnett description for effective media we study the radiative heat transfer between two nanoporous materials. We show that the heat ïŹux can be sig-niïŹcantly enhanced by air inclusions, which we explain by:(a) the presence of additional surface waves that give rise to supplementary channels for heat transfer throughout the gap, (b) an increase in the contribution given by the ordinary surface waves at resonance, (c) and the appearance of frustrated modes over a broad spectral range. We generalize the known expression for the nanoscale heat ïŹux for anisotropic metamaterials
Magnifying NASA Roman GBTDS exoplanet science with coordinated observations by ESA Euclid
The ESA Euclid mission is scheduled to launch on July 1st 2023. This White
Paper discusses how Euclid observations of the Galactic Bulge Time Domain
Survey (GBTDS) area could dramatically enhance the exoplanet science output of
the Nancy Grace Roman Space Telescope (Roman). An early Euclid pre-imaging
survey of the Roman GBTDS fields, conducted soon after launch, can improve
proper motion determinations for Roman exoplanet microlenses that can yield a
factor of up to improvement in exoplanet mass measurements. An
extended Euclid mission would also enable the possibility of sustained
simultaneous observations of the GBTDS by Euclid and Roman that would achieve
large gains in several areas of Roman exoplanet science, including science that
is impossible to achieve with Roman alone. These include: a comprehensive
demographic survey for free-floating planets that includes precision mass
measurements to establish the true nature of individual candidates; detection,
confirmation and mass measurements of exomoons; direct exoplanet mass
measurements through parallax and finite source size effects for a large sample
of bound exoplanets detected jointly by Euclid and Roman; enhanced
false-positive discrimination for the large samples of transiting planets that
Roman will detect. Our main recommendation to NASA and ESA is to initiate a
Joint Study Group as early as possible that can examine how both missions could
best conduct a coordinated campaign. We also encourage flexibility in the GBTDS
scheduling.Comment: 15 pages. Submission to the NASA Roman Core Community Survey White
Paper Cal
Single photon generation by pulsed excitation of a single dipole
The fluorescence of a single dipole excited by an intense light pulse can
lead to the generation of another light pulse containing a single photon. The
influence of the duration and energy of the excitation pulse on the number of
photons in the fluorescence pulse is studied. The case of a two-level dipole
with strongly damped coherences is considered. The presence of a metastable
state leading to shelving is also investigated.Comment: 17 pages, 4 figures, submitted to PR
- âŠ