Status and Perspectives of INRIM Sr Cavity-Enhanced Optical Clock

We report on the status of the strontium optical lattice clock at INRIM and its development towards a cavity-enhanced optical frequency standard exploiting quantum techniques. We have recently developed a novel method to perform high-fidelity spectral purity transfer based on serrodyne optical frequency shifting. We estimated the phase noise induced by the modulation setup by developing a novel composite self-heterodyne interferometer. The consequent short-term stability of our clock is presented, showing collision-limited interaction time in the bosonic
⁸⁸
Sr clock. We also outline the progress towards a cavity-enhanced optical lattice clock. We present a numerical study on collective spin-squeezed states produced by QND continuous measurement of a lossy cavity and its relevance for a Sr optical lattice clock.