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 read-out, 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.
Highlights
Optical clocks—based on interrogation of ultranarrow optical transitions in ions or neutral atoms—have surpassed traditional microwave clocks in both relative frequency stability and accuracy [1,2,3,4]
Single-atom detection and control techniques have propelled quantum simulation and computing applications based on trapped atomic arrays; in particular, ion traps [10], optical lattices [11], and optical tweezers [12,13]
To compare our experimental results with theory predictions, we develop an ab initio Monte Carlo (MC) clock simulation [33] (Appendix A), which directly incorporates laser noise, projective readout, finite temperature, and feedback dynamics, resulting in higher predictive power compared to traditionally used analytical methods [1]
Summary
Optical clocks—based on interrogation of ultranarrow optical transitions in ions or neutral atoms—have surpassed traditional microwave clocks in both relative frequency stability and accuracy [1,2,3,4]. Bofaðs1ed.9o–n2.t2hÞe×M1C0−m15o=dpelffiτffi, we for predict a fractional instability single-clock operation, which would have shorter dead time than that in self-comparpisffioffiffinffiffi.ffi We further demonstrate a direct evaluation of the 1= NA dependence of clock stability with atom number NA, on top of a laser-noise-dominated background, through an atom-byatom system-size-selection technique. This measurement and the MC model strongly indicate that the instability is limited by the frequency noise of our local oscillator.
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