Compact, vibration-insensitive atomic gravity and inertial sensor
Abstract
Atomic accelerometers are among the most accurate tools for measuring gravity in thelaboratory. They have also been developed towards airborne sensing, shipborne surveys, or - inour own work - land-based campaigns. To date, however, they suffer from severe tradeoffsbetween size and sensitivity, with atomic fountains as high as 10 meters needed for aninterrogation time of 2 seconds. Atomic accelerometers are also excessively sensitive tovibrations, as compared to classical ones. Atoms interact with the environment only during veryshort (100-s) laser pulses; this sparse sampling causes aliasing. It results in a slow (Hz-level)signal bandwidth compared to a very large (10-100 kHz) noise bandwidth. Finally, atomicrotation and acceleration sensors only operate when aligned precisely vertically, lest the atomsdrop out of the laser beam used to address them.We have recently introduced a new paradigm to atom interferometry that promises to overcomethese limitations. Instead of measuring gravity by dropping atoms, we hold them for up to 20seconds in an optical lattice. This eliminates the need for a tall atomic fountain. Because theatoms interact with the platform for an extended period, the signal and noise bandwidth arenearly equal, suppressing the sensitivity to vibrations by 2-3 orders of magnitude.We propose to turn this recent breakthrough into a demonstration that atomic accelerometers canoperate under real-world conditions. This proposal has three main technical objectives: In Aim 1,we will remove technical limitations on the data rate. Then, we will increase the wavepacketseparation, attempting to simultaneously increase the sensitivity of the experiment. In Aim 2, wewill conduct simulations that will help us decide on the optimum approach to 3-D confinement,whether a blue- or red-detuned optical lattice, both in combination with a blue-detuned donutbeam, is more favorable. The simulations will first be optimized by comparing them withexperimental data obtained in Aim 1. In Aim 3, we will demonstrate the lattice interferometer with3-D confinement and test its performance, including tests under tilt.This work would lead the way towards atomic inertial sensors that could operate on ships. Evenwithout classical vibration isolation or gimbals, it could tolerate rotational motion in heavy seas.The work could also lead to rotation sensors and gravity gradiometers that can operate undersimilar conditions.The goal is to create an atom interferometer that can take data even while tilted substantially(e.g., 90 degrees) relative to the vertical. (While construction of such a sensor is outside thescope of this proposal, we will build and test a lab-based prototype under smaller tilt angles,generating the preliminary data necessary to justify such an investment). Several of these sensorscould be combined for multiaxis sensing, sharing a laser system. Using atoms within crossedcavities could be used as an atomic gyroscope that shares the advantages of the cavity-basedaccelerometer, i.e., immunity against vibrations, long coherence, compactness, and operationunder arbitrary orientation.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 20, 2020
- Source ID
- N000142012656
Entities
People
- Holger Mueller
Organizations
- Office of Naval Research
- United States Navy
- University of California Regents