Holographically generated optical ring trap for a chip-scale Sagnac atom interferometer*

There is growing need for alternatives to satellite-enabled navigation, particularly for GNSS-denied environments. Quantum solutions to inertial sensing offer a pathway to resilient dead reckoning, with an ambition for a complete chip-scale quantum navigator. In this work we address the challenge of a Sagnac atom interferometer to enable precise rotational sensing.

Drawing inspiration from "atomtronics" techniques, we create a purely optical trapping potential using a static hologram. We use Fresnel zone plate with high spatial resolution and two-bit phase depth to generate smooth, ring-shaped optical potentials with a radii in the range of 5 μm to 2 mm [1]. This range of ring geometries allows us to optimize trap depth in addition to interrogation time and enclosed area, thereby enhancing sensitivity for rotation sensing.

We demonstrate the initial trapping of approximately 10⁵ laser-cooled atoms in an optical waveguide of radius 250μm. We examine localised loading of pre-cooled atoms from a separate single-beam dipole trap. These results are a key step toward interferometry on an adaptable and scalable platform, and ultimately towards miniaturization.



[1] V. A. Henderson, M. Y. H. Johnson, Y. B. Kale, P. F. Griffin, E. Riis, and A. S. Arnold, "Optical characterisation of micro-fabricated Fresnel zone plates for atomic waveguides," Opt. Express 28, 9072-9081 (2020)