Mobile gravimetry is important in metrology, navigation, geodesy, and geophysics. Atomic gravimeters could be among the most accurate mobile gravimeters but are currently constrained by being complex and fragile. Here, we demonstrate a mobile atomic gravimeter, measuring tidal gravity variations in the laboratory and surveying gravity in the field. The tidal gravity measurements achieve a sensitivity of 37 μGal/ (1 μGal = 10 nm/s) and a long-term stability of better than 2 μGal, revealing ocean tidal loading effects and recording several distant earthquakes. We survey gravity in the Berkeley Hills with an uncertainty of around 0.04 mGal and determine the density of the subsurface rocks from the vertical gravity gradient. With simplicity and sensitivity, our instrument paves the way for bringing atomic gravimeters to field applications.
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http://dx.doi.org/10.1126/sciadv.aax0800 | DOI Listing |
Sci Rep
November 2024
Department of Electrical and Computer Engineering, University of California Santa Barbara, Santa Barbara, CA, 93106, USA.
Today's precision experiments for timekeeping, inertial sensing, and fundamental science place strict requirements on the spectral distribution of laser frequency noise. Rubidium-based experiments utilize table-top 780 nm laser systems for high-performance clocks, gravity sensors, and quantum gates. Wafer-scale integration of these lasers is critical for enabling systems-on-chip.
View Article and Find Full Text PDFInertial sensors utilizing cold atom interferometry are advancing toward real-world applications, necessitating optical systems with superior integration and stability. We have developed a highly integrated and stable optical system for a fountain-type Rb atom gravimeter, utilizing dual fiber laser outputs to generate all the laser beams. The optical system design involves bonding miniaturized optical components onto quartz glass plates, significantly reducing the volume of the optical module while maintaining high spatial laser utilization efficiency.
View Article and Find Full Text PDFThere is a continuous interest in shrinking the dimensions of portable atomic gravimeters. This inevitably ends up truncating the Gaussian wings of the excitation laser beams whose effect has not been properly quantified yet. The diffraction pattern created from this aperture creates ripples in the wavefront in both the phase and the intensity.
View Article and Find Full Text PDFSensors (Basel)
April 2024
School of Automation and Intelligence, Beijing Jiaotong University, Beijing 100044, China.
Many efforts have been taken in recent years to push atomic gravimeters toward practical applications. We demonstrate an atomic gravimeter named NIM-AGRb2 that is transportable and suitable for high-precision gravity measurements. Constraint-structured active vibration isolation (CS-AVI) is used to reduce the ground vibration noise.
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