Entanglement-enhanced optical atomic clocks

Recent developments in atomic physics have enabled the experimental generation of many-body entangled states to boost performance quantum sensors beyond Standard Quantum Limit (SQL). This limit is imposed by inherent projection noise a measurement. In this Perspective article, we describe commonly used methods create operate SQL. particular, focus on potential applying entanglement state-of-the-art optical clocks. addition, present recently developed time-reversal protocols that make use complex with high Fisher information without requiring sub-SQL measurement resolution. We discuss prospects for reaching near-Heisenberg limited metrology based such protocols.