Sampling quantum states via heterodyne measurements with non-classical probe states

We describe an intrinsically non-classical method for the reconstruction of the quantum slate defining the signal mode of a heterodyne set-up. This is achieved by mixing the signal mode with a probe mode prepared in a Schrodi nger-cat state. The emerging quantum interferences in the output photocurre nt allow us to map out the state of the signal mode. We emphasize that the interference term actually serves as a complete phase representation of a q uantum state leading to a simple reconstruction algorithm. (C) 1999 Elsevie r Science B.V. All rights reserved.