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

Citation

Madjarov, Ivaylo Sashkov (2021) Entangling, Controlling, and Detecting Individual Strontium Atoms in Optical Tweezer Arrays. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/d1em-dt34. https://resolver.caltech.edu/CaltechTHESIS:01292021-001639979

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 state-detection 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.

Thesis Files