Collective excitation interferometry with a toroidal Bose-Einstein condensate

Abstract

The precision of compact inertial sensing schemes using trapped-and guided-atom interferometers has been limited by uncontrolled phase errors caused by trapping potentials and interactions. Here, we propose an acoustic interferometer that uses sound waves in a toroidal Bose-Einstein condensate to measure rotation, and we demonstrate experimentally several key aspects of this type of interferometer. We use spatially patterned light beams to excite counter-propagating sound waves within the condensate and use in situ absorption imaging to characterize their evolution. We present an analysis technique by which we extract separately the oscillation frequencies of the standing-wave acoustic modes, the frequency splitting caused by static imperfections in the trapping potential, and the characteristic precession of the standing-wave pattern due to rotation. Supported by analytic and numerical calculations, we interpret the noise in our measurements, which is dominated by atom shot noise, in terms of rotation noise. While the noise of our acoustic interferometric sensor, at the level of ∼ rad s −1 / √ Hz, is high owing to rapid acoustic damping and the small radius of the trap, the proof-of-concept device does operate at 10 4 − 10 6 times higher density and in a volume 10 9 times smaller than free-falling atom interferometers.

Interferometric measurement of micro-g acceleration with levitated atoms

“…Other interferometer schemes use external trapping potentials to prevent the gravitational acceleration by channelling the wave packets along magnetic [20,21] and optical [22,23] waveguides. External guiding and trapping potentials allow for equally long observation times [24], however, they introduce additional challenges.…”

Geometry-induced modification of fluctuation spectrum in quasi-two-dimensional condensates

“…Following which, toroidal condensates of atomic 23 Na [4], and 87 Rb [5] have been achieved using LG l 0 beams [28]. Furthermore, toroidal trapping potentials for 87 Rb condensates have been realized by combining an RF-dressed magnetic trap with an optical potential [3] or by the intersection of three light beams as elucidated in [6]. Our present investigation has profound experimental implications since, the more commonly used approach to produce toroidal traps using LG p l laser beams do not have limiting case equivalent to a harmonic oscillator potential.…”

A SQUID Analog with a Bose-Einstein Condensate

“…Atom SQUID counterparts of both types of SQUID are possible: a ''dc atom SQUID'' with two junctions, and a ''rf atom SQUID'' with a single junction. BECs have been created in toroidal traps using a magnetic trap with a repulsive optical trap at the center [7], a Laguerre-Gaussian mode of a laser beam [8,9], superpositions of attractive and repulsive optical dipole potentials [10], and a painted potential [11,12]. Separately, JJs for BECs have been realized with interference of laser beams [13,14], a magnetic trap with a repulsive barrier from a laser beam [15], and a radio frequency dressed magnetic trap [16].…”