Novel Movements for Optical Clocks and Sensors The international online workshop took place from 20 to 22 September 2021. See the News section. Ultra-stable optical oscillators from quantum coherent and entangled systems See the latest Publishable Summary here. Optical clocks require more stable optical oscillators to accelerate the redefinition of the SI second, bring excellent fundamental science to metrology and enable applications for innovative sensors in clock-based geodesy. While the application of quantum measurement strategies in atomic clocks and sensors via multi-particle and light-matter interactions is at the proof-of-principle stage, this project will implement and further develop state-of-the-art quantum measurement strategies on optical oscillators of metrological relevance. It will impact on metrology and sensing with cold atomic systems and optical devices, as well as in those techniques used in scalable quantum information processing and simulation. The overall objective of this project is to realise a new generation of ultra-stable optical oscillators which take advantage of quantum technologies. Knowledge transfer in theoretical and experimental quantum manipulation from quantum optics and quantum computing, to the optical frequency metrology field is at the heart of the project. The implementation, study and characterisation of both established and brand-new methods to develop quantum-enhanced optical oscillators toward a 10-17 relative instability at one second integration time is targeted. This will enable the operation of optical clocks and atomic sensors at their projected accuracy limits of 10-18 with practical measurement times ranging from minutes to hours. Non-classical techniques will be introduced to overcome technical obstacles and the Quantum projection noise (QPN) limit, to approach the Heisenberg noise limit. Specific objectives of the project are: To demonstrate entanglement-enhanced spectroscopy in optical lattice-based and ion-based clocks. In particular, to design and study spin-squeezing via quantum non-demolition methods to go beyond the quantum projection noise (QPN) at the 10-16 instability level at 1 s and study entanglement techniques in ion-based clocks to overcome the single-ion QPN limit. (Work package 1, 2 & 4) To stabilise an optical oscillator at the QPN limit in the collective atom-cavity strong coupling regime, identifying suitable strategies to surpass the QPN limit with intrinsic field-shift compensation. (Work package 3) To develop an active frequency standard based on optically-trapped ultra-cold atoms with engineered lattice topologies to supersede thermal-noise limited optical cavities. (Work package 3 & 4) To demonstrate elementary scaling-of-entanglement operations with ion strings across multiple trapping segments towards increased sensitivity of measurement beyond classical limits. (Work package 4) To disseminate the results among the quantum optics and cold atoms community in order to advance fundamental research in metrology and enable further applications for innovative sensors in clock‑based geodesy. (Work package 5)
