Direct measurement of the Wigner function of a one-photon Fock state in a cavity

Phys Rev Lett. 2002 Nov 11;89(20):200402. doi: 10.1103/PhysRevLett.89.200402. Epub 2002 Oct 28.


We have measured the complete Wigner function W of the vacuum and of a single-photon state for a field stored in a high-Q cavity. This experiment implements the direct Lutterbach and Davidovich method [L. G. Lutterbach and L. Davidovich, Phys. Rev. Lett. 78, 2547 (1997)]] and is based on the dispersive interaction of a single circular Rydberg atom with the cavity field. The nonclassical nature of the single-photon field is exhibited by a region of negative W values. Extensions to other nonclassical cavity field states are discussed.