High Sensitivity Multi-Axes Rotation Sensing Using Large Momentum Transfer Point Source Atom Interferometry

Abstract

A point source interferometer (PSI) is a device where atoms are split and recombined by applying a temporal sequence of Raman pulses during the expansion of a cloud of cold atoms behaving approximately as a point source. The PSI can work as a sensitive multi-axes gyroscope that can automatically filter out the signal from accelerations. The phase shift arising from the rotations is proportional to the momentum transferred to each atom from the Raman pulses. Therefore, by increasing the momentum transfer, it should be possible to enhance the sensitivity of the PSI. Here, we investigate the degree of enhancement in sensitivity that could be achieved by augmenting the PSI with large momentum transfer (LMT) employing a sequence of many Raman pulses with alternating directions. We analyze how factors such as Doppler detuning, spontaneous emission, and the finite initial size of the atomic cloud compromise the advantage of LMT and how to find the optimal momentum transfer under these limitations, with both the semi-classical model and a model under which the motion of the center of mass of each atom is described quantum mechanically. We identify a set of realistic parameters for which LMT can improve the PSI by a factor of nearly 40.

Sensitivity of a Point-Source-Interferometry-Based Inertial Measurement Unit Employing Large Momentum Transfer and Launched Atoms

“…We next consider a PSI augmented with LMT. In Figure 1, we describe schematically the basic approach for LMT for a PSI [14,[16][17][18]. Recalling briefly, the LMT scheme works as follows.…”

“…Refs. [14,15] developed heuristic expressions for the rotation sensitivity of a PSI without any analysis of the acceleration sensitivity.…”

“…As such, an analysis of the sensitivity of rotation sensing and accelerometry for a PSI is very different from that of a conventional atomic interferometer. To the best of our knowledge, there are only sensitivity analyses for rotation sensing, and they are heuristic [14,15]. In this paper, we present a systematic and rigorous analysis of both acceleration and rotation sensitivity of a PSI.…”

“…In order to determine the ultimate capability of a PSI, we also consider the case when Raman-transition-based large momentum transfer (LMT) [14,[16][17][18] is incorporated in order to enhance the sensitivity for both rotation sensing and accelerometry. The way to implement LMT is to apply additional Raman π pulses in opposite effective directions.…”

Enhanced Readout from Spatial Interference Fringes in a Point-Source Cold Atom Inertial Sensor

“…Compared with direct fitting of the fringes from a raw image, the measurement precision of spatial periods is improved by one order of magnitude, leading to about twice-higher precision of angular velocity measurements out of the same atom interferometer. This technique can be combined with a variety of techniques to obtain an increase in measurement performance, for example with LMT for higher sensitivity [14].…”