Fock state superpositions in cavity QED with dark atoms

Abstract

We have proposed a new scheme for generating Fock states in a cavity by “adiabatic passage from the vacuum.” In addition we have shown that an atomic Zeeman coherence can be mapped one-to-one to a photon coherence in a cavity. To the extent that arbitrary Zeeman coherences can be prepared in an atom by radio frequency fields and optical pumping, a “general superposition state” can be prepared in the cavity. The maximum number of photons in these states is limited by the Zeeman degeneracy. We emphasize that the scheme is robust against atomic spontaneous emission, and that the method of preparing the photon states is deterministic, since the atoms leave the cavity in a single final (pure) state.

Finally, we note that all of the adiabatic passage schemes presented above are reversible, i.e., by reversing the order of g(t) and Θ(t), states of the cavity field(s) can be mapped onto atomic ground-state sublevels. Probing these sublevels following the passage of the atom through a cavity would thus provide detailed information on the field that was present in the cavity. Hence, we would also like to propose adiabatic transfer as a powerful tool for the measurement of cavity fields.