  In this paper we describe that the optically pumped frequency standards can
have frequency stability beyond the quantum noise limit by detecting the Ramsey
resonance through the squeezed light. In this paper we report that instead of
considering the interaction of entangled atoms in the microwave region, it will
be more practical to create the entanglement of the atoms in the detection
region using the squeezed light, which is also used for the detection of the
Ramsey resonance. The advantage of squeezing can be derived when the technical
noises have been removed.

Quantum Physics