CAREER: Operating an Optical Atomic Clock Beyond the Laser Coherence and below the Projection Limit

University Of Illinois At Urbana-Champaign, Urbana IL

Investigators

Abstract

Optical atomic clocks are mankind’s most accurate metrological tool with fractional instabilities at the 10^-18 level. This corresponds to losing less than one second in the entire age of the universe. Such accuracy not only enables incredible timing precision, but also facilitates the study of phenomena that may affect the passage of time such as gravity, dark matter, and the variation of fundamental constants. Research on future generations of optical atomic clocks is focused on further improving accuracy and/or allowing a comparable accuracy to be achieved in deployed systems operating in real-world environments. This work will draw from the toolbox of quantum information science to improve the resource efficiency of optical clocks by using on-the-fly measures such as those found in quantum error correction and by using programmable entanglement generation. This research will provide undergraduate and graduate students with hands-on experience in precision metrology and atomic quantum science. This experience, along with curricular innovations and outreach to the broader community, will help promote the growth and diversity of the American quantum workforce. The operating principle of optical clocks involves comparing a sub-Hz-linewidth laser oscillator to an ultra-narrow atomic transition to correct its frequency fluctuation and drift. The main limitations on clock performance stem from (1) the baseline stability of the laser oscillator, and (2) the atomic resources needed to correct laser frequency fluctuations whose accuracy is hampered by the projective nature of quantum measurements. This work seeks to address both issues by enabling independent operation of two atomic array optical clocks within the same apparatus and by using an optical cavity to engineer spin squeezing that mitigates projection noise. Specifically, by levering the rich atomic structure of ytterbium-171, one clock subsystem will be used for real-time correction of the laser phase during the interrogation of the other clock subsystem via ‘mid-circuit’ operations, enabling nearly a 10-times extension beyond the laser coherence time. This work merges the capabilities of neutral-atom quantum computers, optical atomic clocks, and quantum networking devices into one system. It will thus lead to advances of broad societal impact such as fault-tolerant quantum processors as well as quantum networks of optical atomic clocks that can provide quantum-secured timekeeping and the ability to search for new physics. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.