Quantum self-homodyne tomography with an empty cavity

We develop a scheme to reconstruct the optical quantum state of a single-mode bright light field by using the dispersion characteristics of the empty cavity. The input field has a strong coherent component at frequency ω0, which serves as a local oscillator (LO) to measure its two-sideband mode at ω0±Ω. We control the relative phase of the 0–2π range between the LO and the two-sideband mode by scanning the cavity length, so the optical quantum state is tomographically reconstructed. In the proposed scheme the influence of the space-mode mismatch between the LO and measured mode on the quantum efficiency is eliminated, and this scheme can conveniently be used in some quantum optical systems in which LO field cannot be available.