Abstract

In the present work it is demonstrated how the quantum state of a single signal mode can be inferred from two-detector photocount statistics. The outline of the scheme is simple: the signal is mixed on the beam-splitter with a known probe field, or set of different probe fields, and the photocount statistics is recorded. It is shown [1] that for the certain choices of the probe field it is possible to establish a one-to-one correspondence between the elements of the density matrix of the signal field and the set of photocount probabilities. It is also shown that the reconstruction of the signal can be done measuring only the probability of having zero counts on both detectors. As consequence, one can use for the reconstruction the detectors able only to distinguish between presence and absence of photons. It is interesting, that the latter variant of the scheme works only for non-ideal detectors, and can even be improved to some extent by making the detectors less efficient.

© 1998 IEEE