490 research outputs found
Accelerometer using atomic waves for space applications
The techniques of laser cooling combined with atom interferometry make
possible the realization of very sensitive and accurate inertial sensors like
gyroscopes or accelerometers. Besides earth-based developments, the use of
these techniques in space should provide extremely high sensitivity for
research in fundamental physics, Earth's observation and exploration of the
solar system
Stability comparison of two absolute gravimeters: optical versus atomic interferometers
We report the direct comparison between the stabilities of two mobile
absolute gravimeters of different technology: the LNE-SYRTE Cold Atom
Gravimeter and FG5X\#216 of the Universit\'e du Luxembourg. These instruments
rely on two different principles of operation: atomic and optical
interferometry. The comparison took place in the Walferdange Underground
Laboratory for Geodynamics in Luxembourg, at the beginning of the last
International Comparison of Absolute Gravimeters, ICAG-2013. We analyse a 2h10
duration common measurement, and find that the CAG shows better immunity with
respect to changes in the level of vibration noise, as well as a slightly
better short term stability.Comment: 6 page
Enhancing the area of a Raman atom interferometer using a versatile double-diffraction technique
IIn this paper we demonstrate a new scheme for Raman transitions which
realize a symmetric momentum-space splitting of , deflecting the
atomic wave-packets into the same internal state. Combining the advantages of
Raman and Bragg diffraction, we achieve a three pulse state labelled
interferometer, intrinsically insensitive to the main systematics and
applicable to all kind of atomic sources. This splitting scheme can be extended
to momentum transfer by a multipulse sequence and is implemented
on a interferometer. We demonstrate the area enhancement by
measuring inertial forces
How to estimate the differential acceleration in a two-species atom interferometer to test the equivalence principle
We propose a scheme for testing the weak equivalence principle (Universality
of Free Fall) using an atom-interferometric measurement of the local
differential acceleration between two atomic species with a large mass ratio as
test masses. A apparatus in free fall can be used to track atomic free-fall
trajectories over large distances. We show how the differential acceleration
can be extracted from the interferometric signal using Bayesian statistical
estimation, even in the case of a large mass and laser wavelength difference.
We show that this statistical estimation method does not suffer from
acceleration noise of the platform and does not require repeatable experimental
conditions. We specialize our discussion to a dual potassium/rubidium
interferometer and extend our protocol with other atomic mixtures. Finally, we
discuss the performances of the UFF test developed for the free-fall (0-g)
airplane in the ICE project (\verb"http://www.ice-space.fr"
Double diffraction in an atomic gravimeter
We demonstrate the realization of a new scheme for cold atom gravimetry based
on the use of double diffraction beamsplitters recently demonstrated in
\cite{Leveque}, where the use of two retro-reflected Raman beams allows
symmetric diffraction in momenta. Though in principle
restricted to the case of zero Doppler shift, for which the two pairs of Raman
beams are simultaneously resonant, we demonstrate that such diffraction pulses
can remain efficient on atoms with non zero velocity, such as in a gravimeter,
when modulating the frequency of one of the two Raman laser sources. We use
such pulses to realize an interferometer insensitive to laser phase noise and
some of the dominant systematics. This reduces the technical requirements and
would allow the realization of a simple atomic gravimeter. We demonstrate a
sensitivity of per shot
Effective velocity distribution in an atom gravimeter: effect of the convolution with the response of the detection
We present here a detailed study of the influence of the transverse motion of
the atoms in a free-fall gravimeter. By implementing Raman selection in the
horizontal directions at the beginning of the atoms free fall, we characterize
the effective velocity distribution, ie the velocity distribution of the
detected atom, as a function of the laser cooling and trapping parameters. In
particular, we show that the response of the detection induces a pronounced
asymetry of this effective velocity distribution that depends not only on the
imbalance between molasses beams but also on the initial position of the
displaced atomic sample. This convolution with the detection has a strong
influence on the averaging of the bias due to Coriolis acceleration. The
present study allows a fairly good understanding of results previously
published in {\it Louchet-Chauvet et al., NJP 13, 065025 (2011)}, where the
mean phase shift due to Coriolis acceleration was found to have a sign
different from expected
Hybridizing matter-wave and classical accelerometers
We demonstrate a hybrid accelerometer that benefits from the advantages of
both conventional and atomic sensors in terms of bandwidth (DC to 430 Hz) and
long term stability. First, the use of a real time correction of the atom
interferometer phase by the signal from the classical accelerometer enables to
run it at best performances without any isolation platform. Second, a
servo-lock of the DC component of the conventional sensor output signal by the
atomic one realizes a hybrid sensor. This method paves the way for applications
in geophysics and in inertial navigation as it overcomes the main limitation of
atomic accelerometers, namely the dead times between consecutive measurements
Continuous Cold-atom Inertial Sensor with Rotation Stability
We report the operation of a cold-atom inertial sensor which continuously
captures the rotation signal. Using a joint interrogation scheme, where we
simultaneously prepare a cold-atom source and operate an atom interferometer
(AI) enables us to eliminate the dead times. We show that such continuous
operation improves the short-term sensitivity of AIs, and demonstrate a
rotation sensitivity of in a
cold-atom gyroscope of Sagnac area. We also demonstrate a
rotation stability of at s of integration time,
which establishes the record for atomic gyroscopes. The continuous operation of
cold-atom inertial sensors will enable to benefit from the full sensitivity
potential of large area AIs, determined by the quantum noise limit.Comment: 4 pages, 3 figure
A cold atom pyramidal gravimeter with a single laser beam
International audienceWe demonstrate a scheme for realizing a compact cold atom gravimeter. The use of a hollow pyramidal configuration allows to achieve all functions: trapping, interferometer and detection with a unique laser beam leading to a drastic reduction in complexity and volume. In particular, we demonstrate a relative sensitivity to acceleration of gravity (g) of 1.7 à 10-7 at one second, with a moderate laser power of 50 mW. This simple geometry combined to such a high sensitivity opens wide perspectives for practical applications (P. Bouyer and A. Landragin, patent n° FR2009/000252, 2009)
Metrology with Atom Interferometry: Inertial Sensors from Laboratory to Field Applications
Developments in atom interferometry have led to atomic inertial sensors with
extremely high sensitivity. Their performances are for the moment limited by
the ground vibrations, the impact of which is exacerbated by the sequential
operation, resulting in aliasing and dead time. We discuss several experiments
performed at LNE-SYRTE in order to reduce these problems and achieve the
intrinsic limit of atomic inertial sensors. These techniques have resulted in
transportable and high-performance instruments that participate in gravity
measurements, and pave the way to applications in inertial navigation.Comment: 7 pages, 5 figure
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