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Applied Physics Letters

A field-deployable compact gravimeter based on a grating magneto-optical trap with μGal-level long-term stability

Sangwon Seo, Hyun-Gue Hong, J. Lee, Sang Eon Park, Taeg Yong Kwon, Sanglok Lee, Jeongju Choi, Meungho Seo, Jongcheol Park, Sang-Bum Lee

Published Feb 9, 2026• 1 citation
Publisher

Abstract

We present a compact quantum gravimeter based on a grating magneto-optical trap using 87Rb atoms that achieves μGal-level long-term stability without passive vibration isolation. The sensor head integrates magnetic shielding, an ion pump, optical components, and a classical seismometer within a total volume of less than 75L. The gravimeter achieves a sensitivity of 270 μGal/Hz and a stability of 5 μGal at a 1-h average with the long-term gravity record in good agreement with the theoretical tidal model. These results demonstrate a field-deployable platform for portable and chip-integrable quantum gravimetry.

DOI
10.1063/5.0307253

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Nature Communications•Sep 1, 2022•101 citations
We present a compact quantum gravimeter based on a grating magneto-optical trap using 87Rb atoms that achieves μGal-level long-term stability without passive vibration isolation. The sensor head integrates magnetic shielding, an ion pump, optical components, and a classical seismometer within a total volume of less than 75L. The gravimeter achieves a sensitivity of 270 μGal/Hz and a stability of 5 μGal at a 1-h average with the long-term gravity record in good agreement with the theoretical tidal model. These results demonstrate a field-deployable platform for portable and chip-integrable quantum gravimetry.
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We present an ultrahigh-sensitivity gravimeter based on an 87{}^{87}87Rb atom interferometer using stimulated Raman transitions. Compared with our previous work, a two-dimensional magneto-optical trap is added in the new gravimeter to increase the atom number and improve the detection signal-to-noise ratio, and a better optical phase-locked loop system is used to reduce the phase noise of Raman beams. Benefiting from these efforts and the excellent performance of the active vibration isolator, a short-term sensitivity of about 4.2 $\ensuremath{\mu}\text{Gal}/\sqrt{\text{Hz}}$ ($1\phantom{\rule{4pt}{0ex}}\ensuremath{\mu}\mathrm{Gal}=1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}$ m/s2\text{m}/{\text{s}}^{2}m/s2) is reached, which improves the sensitivity by a factor of 2 compared with the former best reported value. By a modulation experiment, we further indicate that the residual vibration noise contribution is about 1.2 $\ensuremath{\mu}\text{Gal}/\sqrt{\text{Hz}}$, which implies a possible improvement over the present absolute gravity measurement level by about one order of magnitude. Moreover, we demonstrate a calibration experiment to directly evaluate the sub-$\ensuremath{\mu}$Gal resolution of our gravimeter.
Abstract The extreme miniaturization of a cold-atom interferometer accelerometer requires the development of novel technologies and architectures for the interferometer subsystems. We describe several component technologies and a laser system architecture to enable a path to such miniaturization. We developed a custom, compact titanium vacuum package containing a microfabricated grating chip for a tetrahedral grating magneto-optical trap (GMOT) using a single cooling beam. The vacuum package is integrated into the optomechanical design of a compact cold-atom sensor head with fixed optical components. In addition, a multichannel laser system driven by a single seed laser has been implemented with time-multiplexed frequency shifting using single sideband modulators, reducing the number of optical channels connected to the sensor head. This laser system architecture is compatible with a highly miniaturized photonic integrated circuit approach, and by demonstrating atom-interferometer operation with this laser system, we show feasibility for the integrated photonic approach. In the compact sensor head, sub-Doppler cooling in the GMOT produces 15 μK temperatures, which can operate at a 20 Hz data rate for the atom interferometer sequence. After validating atomic coherence with Ramsey interferometry, we demonstrate a light-pulse atom interferometer in a gravimeter configuration without vibration isolation for 10 Hz measurement cycle rate and T = 0 - 4.5 ms interrogation time, resulting in Δg/g = 2.0e-6. All these efforts demonstrate progress towards deployable cold-atom inertial sensors under large amplitude motional dynamics.