  We propose a hybrid quantum-classical atomic clock protocol where the
interrogation of an ensemble of uncorrelated atoms in a spin-coherent state is
used to feedback one (or more) spin-squeezed atomic ensembles toward their
optimal phase sensitivity point. This protocol overcomes the stability of a
single Ramsey clock and it reaches a Heisenberg-limited stability while
avoiding non-destructive measurements. Analytical predictions are compared with
numerical simulations of clocks operations including correlated 1/f local
oscillator noise.
