Probing the quantum state in a cavity via atomic two-photon transitions

Abstract

This paper contains a theoretical treatment of a scheme for determining phase-dependent features of a single mode of quantized light fields in general states. The proposal involves using a three-level atom, in a cascade configuration, as a detector. The cascade atom, which is on two-photon resonance with the field, is prepared in a coherent superposition of the upper and lower levels, and detection involves measuring the probability of the cascade atom being in the upper level. The results depend on the phase difference between the amplitudes for the field being in N and N + 2 photon states in the number state basis, and are important in describing nonclassical states, such as squeezed and Schrödinger cat states. The analysis is based on a standard dressed atom model approach and a Fourier treatment of the measured signal. The experimental possibilities of realizing this scheme are also discussed.