Entangling, Controlling, and Detecting Individual Strontium Atoms in Optical Tweezer Arrays

Abstract

We present a novel experimental platform for quantum and precision science: single strontium atoms trapped in arrays of optical tweezers. We demonstrate development of this platform along three important fronts: single-atom trapping, imaging, and cooling; coherent control of the ultra-narrow clock transition; and inter-atom entanglement via Rydberg interactions.

In the context of single-atom physics, we demonstrate trapping in tweezer arrays of one- and two-dimensions as well as cooling to the motional ground state. We furthermore show high-fidelity single-atom imaging with extremely low loss, allowing us to image the same atoms thousands of times before losing them and in principle allowing for the assembly of defect-free atom arrays of several hundred sites.

Notably, we show these results in tweezers that are at a magic wavelength for strontium’s clock transition. This feature allows us to perform high-fidelity state rotations on the clock transition. We also demonstrate operation of a single-site resolved atomic-array optical clock — a new atomic clock platform that combines several benefits of optical lattice and single-ion clocks.

From the metastable clock state, we drive the atoms to highly-excited Rydberg states to introduce interactions between nearby atoms. Using a Rydberg blockade in an assembled array of atom pairs, we demonstrate generation of two-atom entangled Bell states with a fidelity of >98%, or >99% with correction for state preparation and measurement errors. Furthermore, we demonstrate an auto-ionization statedetection scheme for Rydberg atoms which improves on the infidelity of previous Rydberg state-detection schemes by over an order of magnitude.

We conclude with several outlooks, including preliminary data on light-cone correlation spreading in a system of 17 interacting atoms. We also discuss prospects for implementing quantum gates, operating a spin-squeezed clock, increasing system size, quantifying many-body state fidelity, and reducing sources of infidelity.