4,988 research outputs found
A Factorization Law for Entanglement Decay
We present a simple and general factorization law for quantum systems shared
by two parties, which describes the time evolution of entanglement upon passage
of either component through an arbitrary noisy channel. The robustness of
entanglement-based quantum information processing protocols is thus easily and
fully characterized by a single quantity.Comment: 4 pages, 5 figure
MIMAC : A micro-tpc matrix for directional detection of dark matter
Directional detection of non-baryonic Dark Matter is a promising search
strategy for discriminating WIMP events from background. However, this strategy
requires both a precise measurement of the energy down to a few keV and 3D
reconstruction of tracks down to a few mm. To achieve this goal, the MIMAC
project has been developed. It is based on a gaseous micro-TPC matrix, filled
with CF4 and CHF3. The first results on low energy nuclear recoils (H, F)
obtained with a low mono-energetic neutron field are presented. The discovery
potential of this search strategy is discussed and illustrated by a realistic
case accessible to MIMAC.Comment: 6 pages, Proc. of the fifth international symposium on large TPCs for
low energy rare event detection, Paris, France, Dec. 2010. To appear in
Journal of Physic
The theory of quantum levitators
We develop a unified theory for clocks and gravimeters using the
interferences of multiple atomic waves put in levitation by traveling light
pulses. Inspired by optical methods, we exhibit a propagation invariant, which
enables to derive analytically the wave function of the sample scattering on
the light pulse sequence. A complete characterization of the device sensitivity
with respect to frequency or to acceleration measurements is obtained. These
results agree with previous numerical simulations and confirm the conjecture of
sensitivity improvement through multiple atomic wave interferences. A realistic
experimental implementation for such clock architecture is discussed.Comment: 11 pages, 6 Figures. Minor typos corrected. Final versio
MIMAC: MIcro-tpc MAtrix of Chambers for dark matter directional detection
Directional detection of non-baryonic Dark Matter is a promising search
strategy for discriminating WIMP events from neutrons, the ultimate background
for dark matter direct detection. This strategy requires both a precise
measurement of the energy down to a few keV and 3D reconstruction of tracks
down to a few mm. The MIMAC (MIcro-tpc MAtrix of Chambers) collaboration has
developed in the last years an original prototype detector based on the direct
coupling of large pixelized micromegas with a special developed fast
self-triggered electronics showing the feasibility of a new generation of
directional detectors. The first bi-chamber prototype has been installed at
Modane, underground laboratory in June 2012. The first undergournd background
events, the gain stability and calibration are shown. The first spectrum of
nuclear recoils showing 3D tracks coming from the radon progeny is presented.Comment: Proceedings of the 4th International Conference on Directional Dark
Matter Detection CYGNUS2013, held in Toyoma (Japan), June 201
Micromegas detector developments for MIMAC
The aim of the MIMAC project is to detect non-baryonic Dark Matter with a
directional TPC. The recent Micromegas efforts towards building a large size
detector will be described, in particular the characterization measurements of
a prototype detector of 10 10 cm with a 2 dimensional readout
plane. Track reconstruction with alpha particles will be shown.Comment: 8 pages, 7 figures Proceedings of the 3rd International conference on
Directional Detection of Dark Matter (CYGNUS 2011), Aussois, France, 8-10
June 2011; corrections on author affiliation
Development of ultra-light pixelated ladders for an ILC vertex detector
The development of ultra-light pixelated ladders is motivated by the
requirements of the ILD vertex detector at ILC. This paper summarizes three
projects related to system integration. The PLUME project tackles the issue of
assembling double-sided ladders. The SERWIETE project deals with a more
innovative concept and consists in making single-sided unsupported ladders
embedded in an extra thin plastic enveloppe. AIDA, the last project, aims at
building a framework reproducing the experimental running conditions where sets
of ladders could be tested
The optical calcium frequency standards of PTB and NIST
We describe the current status of the Ca optical frequency standards with
laser-cooled neutral atoms realized in two different laboratories for the
purpose of developing a possible future optical atomic clock.
Frequency measurements performed at the Physikalisch-Technische Bundesanstalt
(PTB) and the National Institute of Standards and Technology (NIST) make the
frequency of the clock transition of 40Ca one of the best known optical
frequencies (relative uncertainty 1.2e-14) and the measurements of this
frequency in both laboratories agree to well within their respective
uncertainties.
Prospects for improvement by orders of magnitude in the relative uncertainty
of the standard look feasible.Comment: 13 pages, 11 figures, to appear in Comptes Rendus Physiqu
Perturbations of the local gravity field due to mass distribution on precise measuring instruments: a numerical method applied to a cold atom gravimeter
We present a numerical method, based on a FEM simulation, for the
determination of the gravitational field generated by massive objects, whatever
geometry and space mass density they have. The method was applied for the
determination of the self gravity effect of an absolute cold atom gravimeter
which aims at a relative uncertainty of 10-9. The deduced bias, calculated with
a perturbative treatment, is finally presented. The perturbation reaches (1.3
\pm 0.1) \times 10-9 of the Earth's gravitational field.Comment: 12 pages, 7 figure
Violation of Bell inequalities by photons more than 10 km apart
A Franson-type test of Bell inequalities by photons 10.9 km apart is
presented. Energy-time entangled photon-pairs are measured using two-channel
analyzers, leading to a violation of the inequalities by 16 standard deviations
without subtracting accidental coincidences. Subtracting them, a 2-photon
interference visibility of 95.5% is observed, demonstrating that distances up
to 10 km have no significant effect on entanglement. This sets quantum
cryptography with photon pairs as a practical competitor to the schemes based
on weak pulses.Comment: 4 pages, REVTeX, 2 postscript figures include
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