Nonclassical correlations of photon number and field components in the vacuum state - art. no. 013806

It is shown that the quantum jumps in the photon number (n) over cap from z ero to one or more photons induced by backaction evasion quantum nondemolit ion measurements of a quadrature component (x) over cap of the vacuum light held state are strongly correlated with the quadrature component measureme nt results. This correlation corresponds to the operator expectation value [(xnx) over cap] which is equal to one-fourth for the vacuum even though th e photon number eigenvalue is zero. Quantum nondemolition measurements of a quadrature component can thus provide experimental evidence of the nonclas sical operator ordering dependence of the correlations between photon numbe r and held components in the vacuum state.