QUANTUM STATE RECONSTRUCTION BY MULTICHANNEL UNBALANCED HOMODYNING

Multichannel unbalanced homodyning is proposed for measuring the densi ty matrix of a single-mode optical field in the photon-number represen tation. Combining the signal beam and the local oscillator by a high-t ransmittance beam splitter, the interfering field is detected using mu ltichannel photocounting. The density matrix is determined by direct s tatistical sampling of the coincident events recorded for various valu es of the local-oscillator phase. The usefulness of the method is demo nstrated by computer simulations of measurements including error estim ations.