1205.2898 (T. Kiesel et al.)

Universal nonclassicality witnesses for harmonic oscillators    [PDF]

T. Kiesel, W. Vogel

It is shown that a nonclassicality witness, whose expectation value can be measured for all quantum states, can be constructed from every nonclassicality filter. This finding leads to a set of universal witnesses, parameterized by only three real numbers, for the detection of nonclassicality of any quantum state of a harmonic oscillator. An explicit operator expression is given for such a universal witness. The application of the witnesses is demonstrated for a nontrivial example, and its experimental measurement is briefly considered.

View original: http://arxiv.org/abs/1205.2898