Measurement of Local Gravity via a Cold Atom Interferometer

Abstract

We demonstrate a precision measurement of local gravity acceleration in Wuhan by a compact cold atom interferometer. The atom interferometer is in vertical Mach-Zehnder configuration realized using a /2 − − /2 Raman pulse sequence. Cold atoms were prepared in a magneto-optical trap, launched upward to form an atom fountain, and then coherently manipulated to interfere by stimulated Raman transition. Population signal vs Raman laser phase was recorded as interference fringes, and the local gravity was deduced from the interference signal. We have obtained a resolution of 7 × 10 −9 g after an integration time of 236 s under the best vibrational environment conditions. The absolute g value was derived from the chirp rate with a difference of 1.5 × 10 −7 g compared to the gravity reference value. The tidal phenomenon was observed by continuously monitoring the local gravity over 123 h.

Development of an atom gravimeter and status of the 10-meter atom interferometer for precision gravity measurement

“…7, same results without error bars are shown in Ref. [23]. The experimental data agree well with the prediction of the theoretical model, which indicates that the atom gravimeter works well.…”

“…6, and typical M-Z fringes for T = 2, 3, 4 ms are shown in Ref. [23]. Since the total phase shift depends on the chirp rate, α, the effective wave vector of Raman laser, k e f f , and the absolute gravitational acceleration, g, the absolute value of g can be obtained by setting the total phase shift to zero [24], = k e f f · gT 2 − αT 2 = 0 ( 1 )…”

“…Meanwhile, we designed a 10-meter fountain type atom interferometer for precise measurements of gravity, EP test, and gravitational wave detection. In this paper we summarize our works including the laboratory prototype of a laser-cooled 85 Rb atom interferometer [18,19], investigation of magnetic field dependence of coherent population transfer [20], precision measurements of quadratic Zeeman shift [21,22], and local gravity measurement using atom interferometer [23]. The design and the latest progress of the 10-meter atom interferometer are reported for the first time.…”

Self-alignment of a large-area dual-atom-interferometer gyroscope using parameter-decoupled phase-seeking calibrations

“…If we want to seek the phase intersection, the uncertainty of chirped rate should be confined to a range of a few kHz/s, which corresponds to the 10 −4 level of the gravity measurement. To accurately compensate the chirped rate, we construct a M-Z interferometer with the second pair of Raman lasers to measure the gravity compensated chirp rate [26]. Limited by the beam size, the maximum interrogation time is about 2.6 ms, which can give a chirped rate of 25.104 ± 0.001 MHz/s.…”

Multifunctional radio-frequency generator for cold atom experiments

“…In the experiments associated with cold atoms [1][2][3] , for precisely controlling the frequency and amplitude of laser, fast switching and precise frequency tuning are usually achieved by acousto-optical modulator (AOM) [4,5] , which is driven by radio-frequency (RF) signals. At present, many commercially available RF generators are difficult to control multiple AOMs in atomic physics experiments.…”