A pyramid MOT with integrated optical cavities as a cold atom platform for an optical lattice clock

William Bowden,Patrick E G Baird,Ian R Hill,Helen S Margolis,Alvise Vianello,Richard Hobson,Marco Schioppo,Alissa Silva,Patrick Gill

doi:10.1038/s41598-019-48168-3

William Bowden, Patrick E G Baird + Show 7 more

Open Access

https://doi.org/10.1038/s41598-019-48168-3

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Abstract

We realize a two-stage, hexagonal pyramid magneto-optical trap (MOT) with strontium, and demonstrate loading of cold atoms into cavity-enhanced 1D and 2D optical lattice traps, all within a single compact assembly of in-vacuum optics. We show that the device is suitable for high-performance quantum technologies, focusing especially on its intended application as a strontium optical lattice clock. We prepare 2 × 104 spin-polarized atoms of 87Sr in the optical lattice within 500 ms; we observe a vacuum-limited lifetime of atoms in the lattice of 27 s; and we measure a background DC electric field of 12 V m−1 from stray charges, corresponding to a fractional frequency shift of (−1.2 ± 0.8) × 10−18 to the strontium clock transition. When used in combination with careful management of the blackbody radiation environment, the device shows potential as a platform for realizing a compact, robust, transportable optical lattice clock with systematic uncertainty at the 10−18 level.

Highlights

Single beam pyramid magneto-optical traps (MOTs) are well-suited for cold-atom quantum technologies[1] as their compact, elegant design simplifies the optical setup needed for laser cooling
The two-stage MOT is insufficient by itself to realize an optical lattice clock (OLC); atoms must be loaded into a magic-wavelength optical lattice trap so that the clock transition can be probed in the Lamb-Dicke regime[18]
Following the two-stage MOT, atoms are loaded into a 2D optical lattice trap that is generated by coupling a milliwatt of light at 813 nm into the TEM00 modes of the two-crossed enhancement cavities

Summary

Introduction

Single beam pyramid magneto-optical traps (MOTs) are well-suited for cold-atom quantum technologies[1] as their compact, elegant design simplifies the optical setup needed for laser cooling. The two-stage MOT is insufficient by itself to realize an OLC; atoms must be loaded into a magic-wavelength optical lattice trap so that the clock transition can be probed in the Lamb-Dicke regime[18] This motivates the construction of a single monolithic structure capable of supporting both a pyramid MOT and optics to generate the lattice trap. The enhancement provided by the cavity eliminates the need for high power lasers—a benefit for compact systems—and facilitates better characterization of lattice-induced sources of systematic uncertainty To exploit these advantages, we integrate two build-up cavities into the same structure as the pyramid MOT which can either generate independent 1D lattices or be combined to make a 2D lattice. In this report we outline how these challenges can be addressed in a compact cold atom platform, realizing the benefits of in-vacuum trapping optics without compromising the accuracy of the strontium optical lattice clock

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