Optical atomic clocks

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Optical atomic clocks are one of our most precise tools to measure time and frequency. Frequency comparisons between atomic clocks in separate systems are used for geodesy, measuring the space time variation of fundamental constants, and even probing the structure of dark matter. The precision of such comparisons between independent systems will always be limited by the standard quantum limit. This research aims to use the remote entanglement from a quantum network to enhance such frequency comparisons beyond this limit, building upon our previous proof-of-principle demonstration. We will use mixed-species entangling operations to coherently map the remote entanglement initially generated on remote strontium ions to co-trapped calcium ions. Calcium ions have an optical transition that is first-order insensitive to magnetic field fluctuations; we hope to perform frequency comparisons at the lifetime limit of the transition and achieve one of the first few instances of a practical enhancement with entanglement.