Fig. 1: Setup and noise processes.
From: Prospects and challenges for squeezing-enhanced optical atomic clocks
a Measurement and feedback loop to stabilize the laser frequency to an atomic transition. b Periodic measurements with Ramsey time TR and dead time TD in each cycle of total time TC lead to increased instability from the Dick effect. c Quantum projection noise ĪSy for N particles limits the clock stability for short interrogation times but can be decreased with squeezed states thus reducing the inferred phase uncertainty \(\zeta =\xi /\sqrt{N}\) where Ī¾ is the Wineland spin squeezing parameter. d For longer TR the distribution P(Ļ,Ā t) of phases broadens substantially due the laserās decoherence. Inefficient feedback for phases outside the \([-\frac{\pi }{2},\frac{\pi }{2}]\) interval gives the coherence time limit.
