22 research outputs found
Proof-of-principle demonstration of vertical gravity gradient measurement using a single proof mass double-loop atom interferometer
We demonstrate a proof-of-principle of direct Earth gravity gradient
measurement with an atom interferometer-based gravity gradiomter using a single
proof mass of cold 87 rubidium atoms. The atomic gradiometer is implemented in
the so-called double-loop configuration, hence providing a direct gravity
gradient dependent phase shift insensitive do DC acceleration and constant
rotation rate. The atom interferometer (AI) can be either operated as a
gravimeter or a gradiomter by simply adding an extra Raman -pulse. We
demonstrate gravity gradient measurements first using a vibration isolation
platform and second without seismic isolation using the correlation between the
AI signal and the vibration signal measured by an auxilliary classical
accelerometer. The simplicity of the experimental setup (a single atomic source
and unique detection) and the immunity of the AI to rotation-induced contrast
loss, make it a good candidate for onboard gravity gradient measurements.Comment: 11 pages, 7 figure
Atom interferometry based on light pulses : application to the high precision measurement of the ratio h/m and the determination of the fine structure constant
In this paper we present a short overview of atom interferometry based on
light pulses. We discuss different implementations and their applications for
high precision measurements. We will focus on the determination of the ratio
h/m of the Planck constant to an atomic mass. The measurement of this quantity
is performed by combining Bloch oscillations of atoms in a moving optical
lattice with a Ramsey-Bord\'e interferometer
Local gravity measurement with the combination of atom interferometry and Bloch oscillations
We present a local measurement of gravity combining Bloch oscillations and
atom interferometry. With a falling distance of 0.8 mm, we achieve a
sensitivity of 2x10-7 g with an integration time of 300 s. No bias associated
with the Bloch oscillations has been measured. A contrast decay with Bloch
oscillations has been observed and attributed to the spatial quality of the
laser beams. A simple experimental configuration has been adopted where a
single retro-reflected laser beam is performing atoms launch, stimulated Raman
transitions and Bloch oscillations. The combination of Bloch oscillations and
atom interferometry can thus be realized with an apparatus no more complex than
a standard atomic gravimeter
Precise determination of h/m_Rb using Bloch oscillations and atomic interferometry: a mean to deduce the fine structure constant
We use Bloch oscillations to transfer coherently many photon momenta to
atoms. Then we can measure accurately the ratio h/m_Rb and deduce the fine
structure constant alpha. The velocity variation due to the Bloch oscillations
is measured thanks to Raman transitions. In a first experiment, two Raman
pulses are used to select and measure a very narrow velocity class. This method
yields to a value of the fine structure constant alpha^{-1}= 137.035 998 84
(91) with a relative uncertainty of about 6.6 ppb. More recently we use an
atomic interferometer consisting in two pairs of pi/2 pulses. We present here
the first results obtained with this method
Zero-velocity atom interferometry using a retroreflected frequency chirped laser
International audienceAtom interferometry using stimulated Raman transitions in a retroreflected configuration is the first choice in high-precision measurements because it provides low phase noise, a high-quality Raman wave front, and a simple experimental setup. However, it cannot be used for atoms at zero velocity because two pairs of Raman lasers are simultaneously resonant. Here we report a method which allows this degeneracy to be lifted by using a frequency chirp on the Raman lasers. Using this technique, we realize a Mach-Zehnder atom interferometer hybridized with a force balanced accelerometer which provides horizontal acceleration measurements with a short-term sensitivity of 3.2×10−5ms−2/Hz. This technique could be used for multiaxis inertial sensors, tiltmeters, or atom interferometry in a microgravity environment
Absolute airborne gravimetry with a cold atom sensor
Measuring gravity from an aircraft is essential in geodesy, geophysics and exploration. Today, only relative sensors are available for airborne gravimetry. This is a major drawback because of the calibration and drift estimation procedures which lead to important operational constraints and measurement errors. Here, we report an absolute airborne gravimeter based on atom interferometry. This instrument has been first tested on a motion simulator leading to gravity measurements noise of 0.3 mGal for 75 s filtering time constant. Then, we realized an airborne campaign across Iceland in April 2017. From a repeated line and crossing points, we obtain gravity measurements with an estimated error between 1.7 and 3.9 mGal. The airborne measurements have also been compared to upward continued ground gravity data and show differences with a standard deviation ranging from 3.3 to 6.2 mGal and a mean value ranging from-0.7 mGal to-1.9 mGal
Line intensity measurements of methane’s ν3-band using a cw-OPO
We report on absolute line strength measurements of P(1), R(0) and R(1) singlet lines in the 3:3 μm ν3 (C–H stretching) band of methane 12CH4 at referencetemperature T = 296 K. Line strength measurements are performed at low pressure (P <1 Torr) using direct absorption spectroscopy technique based on a widely tunable continuous-wave singly resonant optical parametric oscillator. The 1σ overall accuracy in line strength determinations ranges between 7 and 8 % mostly limited by pressure and frequency measurements. A comparison with previous reported values is made. Our results show good agreement with the HITRAN 2012 database
Combination of Bloch oscillations with a Ramsey-Bord\'e interferometer : new determination of the fine structure constant
We report a new experimental scheme which combines atom interferometry with
Bloch oscillations to provide a new measurement of the ratio
. By using Bloch oscillations, we impart to the atoms up to
1600 recoil momenta and thus we improve the accuracy on the recoil velocity
measurement. The deduced value of leads to a new
determination of the fine structure constant
with a relative uncertainty of . The comparison of this
result with the value deduced from the measurement of the electron anomaly
provides the most stringent test of QED
Phase shift in an atom interferometer induced by the additional laser lines of a Raman laser generated by modulation
The use of Raman laser generated by modulation for light-pulse atom
interferometer allows to have a laser system more compact and robust. However,
the additional laser frequencies generated can perturb the atom interferometer.
In this article, we present a precise calculation of the phase shift induced by
the additional laser frequencies. The model is validated by comparison with
experimental measurements on an atom gravimeter. The uncertainty of the phase
shift determination limits the accuracy of our compact gravimeter at 8.10^-8
m/s^2. We show that it is possible to reduce considerably this inaccuracy with
a better control of experimental parameters or with particular interferometer
configurations