Continuous measurement of photon number with double registration of counts- art. no. 033806

The theory of continuous measurement has been applied to photon counting by means of an atomic beam crossing a cavity and impinging on a field-ionizat ion detector behind. An interesting feature of the proposed measurement con sists in an incoherent frequency down-conversion coupling of the measured m ode to another mode, which, on the assumption that the latter is initially in the vacuum state, results in a second registration of the counts.