1207.5012 (S. Agarwal et al.)

Witnessing non-classicality of a quantum oscillator state by coupling it
to a qubit    [PDF]

S. Agarwal, J. H. Eberly

We propose a new witness operation for the non-classical character of a harmonic oscillator state. The method does not require state reconstruction. For all harmonic oscillator states that are classical, a bound is established for the evolution of a qubit which is coupled to the oscillator. Any violation of the bound can be rigorously attributed to the non-classical character of the initial oscillator state.

View original: http://arxiv.org/abs/1207.5012