Ultra high sensitivity quantum gravi-gradiometer

Valentin Cambier, Joel Gomes Baptista, Leonid A. Sidorenkov +2 more

Joel Gomes Baptista, Louis Pagot, Léo Rol +4 more

Xiangmin Wu, Tianteng Ma, Mingqi Huang +7 more

Lute Maleki, Nan Yu, James M. Kohel

Gravity gradiometers based on atom-wave interferometry hold the promise for increased sensitivity, and suitability for space applications. This capability will significantly advance our knowledge of solid Earth and the oceans, as well as other solar system planets and their moons. The quantum interferometer gravity gradiometer is based on atom-wave interferometry, and is intrinsically more sensitive than laser interferometers, because of the finite mass of the atom and the shorter de Broglie wavelengths associated with atom waves. Recent advances in laser cooling and trapping have made quantum interferometer applications practical. In this paper the principle of the operation of the quantum gravity gradiometer will first be described, together with the progress in its development to date. Estimates for the performance, and projections for the sensitivity will also be presented, together with potential applications to gravity science. Over the past few years advanced in laser cooling has brought about a significant progress towards realization of ultra-high sensitivity gravity gradiometers based on atom wave (matter wave) interferometry. These instruments represent a powerful potential for sensitive measurements of the components of the gravity gradient tensor from space to provide access to three-dimensional maps of geophysical structures deep below the surface. The exquisite sensitivity associated with atom-wave interferometry holds a great promise for new gravity mapping and monitoring capabilities - higher measurement sensitivity, finer spatial resolution, and, most importantly, temporal monitoring. This implies measurement opportunities for the Earth Observing System to develop comprehensive models for the understanding of the planetary inner structure and dynamics, changes in ice sheets and ocean currents, changes in underground water storage, and weather, earthquake, and volcano prediction capabilities. In this paper, we will review briefly the principles of the quantum gravity gradiometer and its advantages in the space environment. We will then describe our laboratory experiment and report some of the component development work towards a space-borne system. Gravity gradiometers based on atom interferometers are currently under development at the Jet propulsion Laboratory under NASA sponsorship.

Fernando Sansò, Federica Migliaccio

Rui Zhang, Rahul Mhaskar, Ken Smith +1 more

We demonstrate a portable all-optical intrinsic scalar magnetic gradiometer composed of miniaturized cesium vapor cells and vertical-cavity surface-emitting lasers (VCSELs). Two cells, with inner dimensions of 5 mm × 5 mm × 5 mm and separated by a baseline of 5 cm, are driven by one VCSEL, and the resulting Larmor precessions are probed by a second VCSEL through optical rotation. The off-resonant linearly polarized probe light interrogates two cells at the same time, and the output of the intrinsic gradiometer is proportional to the magnetic field gradient measured over the given baseline. This intrinsic gradiometer scheme has the advantage of avoiding added noise from combining two scalar magnetometers. We achieve a sensitivity better than 18 fT/cm/√Hz in the gradient measurement. Ultra-sensitive short-baseline magnetic gradiometers can potentially play an important role in many practical applications, such as nondestructive evaluation and unexploded ordnance detection. Another application of the gradiometer is for magnetocardiography (MCG) in an unshielded environment. Real-time MCG signals can be extracted from the raw gradiometer readings. The demonstrated gradiometer greatly simplifies the MCG setup and may lead to a ubiquitous MCG measurement in the future.