Quantum Clocks are More Accurate Than Classical Ones

A clock is, from an information-theoretic perspective, a system that emits information about time. One may therefore ask whether the theory of imposes any constraints on maximum precision clocks. Here we show quantum-over-classical advantage for clocks or, more precisely, task generating what time it is. The argument is based considerations: analyze how accuracy scales with its size, measured in terms number bits could be stored it. We find quantum can achieve quadratically improved compared to purely classical one same size.Received 28 January 2020Revised 20 September 2021Accepted 21 December 2021DOI:https://doi.org/10.1103/PRXQuantum.3.010319Published by American Physical Society under Creative Commons Attribution 4.0 International license. Further distribution this work must maintain attribution author(s) and published article's title, journal citation, DOI.Published SocietyPhysics Subject Headings (PhySH)Research AreasQuantum channelsQuantum entanglementQuantum walksQuantum Information