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 $\pi$-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

New concepts of inertial measurements with multi-species atom interferometry

In the field of cold atom inertial sensors, we present and analyze innovative configurations for improving their measurement range and sensitivity, especially attracting for onboard applications. These configurations rely on multi-species atom interferometry, involving the simultaneous manipulation of different atomic species in a unique instrument to deduce inertial measurements. Using a dual-species atom accelerometer manipulating simultaneously both isotopes of rubidium, we report a preliminary experimental realization of original concepts involving the implementation of two atom interferometers first with different interrogation times and secondly in phase quadrature. These results open the door to a new generation of atomic sensors relying on high performance multi-species atom interferometric measurements

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 $\pi$ 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

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