An Atomic-Array Optical Clock with Single-Atom Readout

Abstract

Currently, the most accurate and stable clocks use optical interrogation of either a single ion or an ensemble of neutral atoms confined in an optical lattice. Here, we demonstrate a new optical clock system based on an array of individually trapped neutral atoms with single-atom readout, merging many of the benefits of ion and lattice clocks as well as creating a bridge to recently developed techniques in quantum simulation and computing with neutral atoms. We evaluate single-site-resolved frequency shifts and short-term stability via self-comparison. Atom-by-atom feedback control enables direct experimental estimation of laser noise contributions. Results agree well with an ab initio Monte Carlo simulation that incorporates finite temperature, projective readout, laser noise, and feedback dynamics. Our approach, based on a tweezer array, also suppresses interaction shifts while retaining a short dead time, all in a comparatively simple experimental setup suited for transportable operation. These results establish the foundations for a third optical clock platform and provide a novel starting point for entanglement-enhanced metrology, quantum clock networks, and applications in quantum computing and communication with individual neutral atoms that require optical-clock-state control.

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Plain Language Summary

Optical clocks have surpassed traditional microwave clocks in both stability and accuracy. They enable new experiments in geodesy, fundamental physics, and quantum many-body physics, in addition to a prospective redefinition of the second. Current optical clocks either interrogate a single ion or an ensemble of lattice-trapped atoms. Ideally, one could merge the benefits of these platforms by developing a clock based on a large array of isolated atoms that can be read out and controlled individually. As a major advance in this direction, we present an atomic-array optical clock with a single-atom-resolved readout of 40 individually trapped neutral atoms.

This new platform benefits from both a large and scalable number of atoms as well as the ability to prepare and read out individual isolated atoms. The latter capability avoids interaction shifts that degrade clock performance and enables the characterization of clock performance on the single-atom level. Specifically, we can measure inhomogeneous systematic errors across the array, and we propose a scheme leveraging single-atom readout to correct for them. We further study how varying the number of atoms contributes to clock stability.

Further, our work enables a myriad of new applications. Specifically, it provides atom-by-atom error evaluation, feedback, and thermometry; facilitates quantum metrology applications, such as quantum-enhanced clocks and clock networks; and enables novel quantum computation, simulation, and communication architectures that require optical-clock-state control combined with single-atom trapping.