Multi-loop and Multi-axis Atomtronic Sagnac Interferometry

Abstract

We report the experimental realization of a large-area and multi-axis atomtronic interferometer in an optical waveguide for rotation sensing. A large enclosed area is achieved through multi-loop operation in a guided atom interferometer using Bose-Einstein condensates. We demonstrate a three-loop interferometer with a total interrogation time of ~ 0.4 s and an enclosed area of 8.7 mm$^2$- the largest reported in a fully guided or one-dimensional setup. High-contrast interference fringes are observed for up to five Sagnac orbits in a smaller loop-area configuration. Our approach enables interleaved rotation measurements about multiple arbitrary axes within the same experimental setup. We present results for area-enclosing interferometers in both horizontal and vertical planes, demonstrating that the interferometer contrast remains comparable across orthogonal orientations of the enclosed area vectors.

Figures (8)

• Figure 1: One-loop moving waveguide unfolded interferometer scheme. The sequence starts by releasing a BEC from a crossed dipole trap into the guide. After an expansion duration of $t_\text{evol.1}$, a delta-kick collimation lens is applied, and right after that a beam splitter (BS) pulse is shone on a collimated wave-packet. After a guide moving time of $T/4$, a mirror (M) pulse is shone that reverses the sign of the atomic momentum. At the mid point of the interferometer at $T/2$, the guide motion is reversed. A second M pulse is applied at $3T/4$. The wave-packets are recombined at $T$ with a second BS at their starting position. Right after the final BS, a delta-kick focusing lens is applied that tightly focuses all the three momentum states in $t_{\text{evol.2}}$, and the three states separate spatially. The dotted curves show the trajectory of the atoms (see main text).
• Figure 2: Accelerometer phase correction. Improvement in the average fringe contrast after applying the phase correction to the individual runs of a 121 ms one-loop static guide interferometer. a) Without phase correction and b) Phase corrected fringe. The gray dots are individual experimental data points, the red points are binned averages of those measurements, and the blue curves are least-squares fit of a cosine function to the average points.
• Figure 3: Multi-loop moving guide interferometry. a) One-loop fringe for $T$ = 124 ms and 2.9 mm$^2$ enclosed area. b) Two-loop fringe for a total $T$ = 246 ms and 5.8 mm$^2$ enclosed area. c) 371 ms total $T$ three-loop fringe with of 8.7 mm$^2$ enclosed area. d) A five-loop fringe for a total $T$ of 108 ms and 0.13 mm$^2$ enclosed area. The guide was moved vertically in all these interferometers. The red (gray) points show the bin-average (raw) fringe data. The blue curve is the cosine fit.
• Figure 4: Multi-axis interferometry. a) Waveguide moving in the horizontal and vertical plane forming two Sagnac loops with orthogonal area vectors for sensing $\Omega_\text{x}$ and $\Omega_\text{z}$. b) One-loop interferometer fringe for the guide moving in the horizontal plane. The interrogation time and enclosed area is 160 ms and 3.2 mm$^2$, respectively.
• Figure 5: Bragg beam setup. a) Bragg laser and AOM control. b) Relevant components of the BEC experiment setup.