Atom-interferometric techniques for measuring uniform magnetic field gradients and gravitational acceleration

Abstract

We discuss techniques for probing the effects of a constant force acting on cold atoms using two configurations of a grating echo-type atom interferometer. Laser-cooled samples of 85 Rb with temperatures as low as 2.4 µK have been achieved in a new experimental apparatus with a wellcontrolled magnetic environment. We demonstrate interferometer signal lifetimes approaching the transit time limit in this system (∼ 270 ms), which is comparable to the timescale achieved by Raman interferometers. Using these long timescales, we experimentally investigate the influence of a homogeneous magnetic field gradient using two-and three-pulse interferometers, which enable us to sense changes in externally applied magnetic field gradients as small as ∼ 4 × 10 −5 G/cm. We also provide an improved theoretical description of signals generated by both interferometer configurations that accurately models experimental results. With this theory, absolute measurements of B-gradients at the level of 3 × 10 −4 G/cm are achieved. Finally, we contrast the suitability of the two-and three-pulse interferometers for precision measurements of the gravitational acceleration, g.

Representation-free description of atom interferometers in time-dependent linear potentials

“…constant [14][15][16][17][18], and the Newtonian gravitational constant [19][20][21][22]. On a more applied side, there has been much activity in the development of interferometers as sensors of acceleration , rotation [44][45][46][47], gravity gradients [48][49][50][51][52][53], magnetic fields and magnetic field gradients [54][55][56][57][58], and dual accelerometer/gyroscopes [59][60][61]. Some of these works have been reviewed in [62,63].…”

Two-dimensional grating magneto-optical trap

“…Matter wave interferometry has demonstrated orders of magnitude improvement over a wide range of precision measurements [1][2][3][4][5][6][7][8]. These successes have spurred interest in transitioning cold atom devices from the lab to more demanding environments [9][10][11][12][13][14][15][16][17].…”

Detection of applied and ambient forces with a matter-wave magnetic gradiometer

“…Alkali atoms offer an attractive medium due to the relatively simple internal structure, and the ability to readily prepare, manipulate, and interrogate them with lasers [1,2]. Atom interferometry in general offers the ability to perform precision measurements in the form of magnetic and gravitational metrology [3][4][5][6][7][8][9][10] and inertial sensing [2,[10][11][12][13][14][15] as well as to test fundamental physics by making measurements of the fine-structure constant [16][17][18][19], the Newtonian gravitational constant [20], atomic polarisabilities [21], tests of the equivalence principle [22], and recent proposals for gravitational wave detection [23]. The use of Bose-Einstein condensates over thermal atoms in interferometry can be favourable due to the low atomic speed and therefore low dispersion, and increased phase coherence offering a high-contrast signal and an increased signal-to-noise ratio [9,24,25].…”