We introduce a family of criteria to detect quantum non-Gaussian states of a harmonic oscillator, that is, quantum states that cannot be expressed as a convex mixture of Gaussian states. In particular, we prove that for convex mixtures of Gaussian states, the value of the Wigner function at the origin of phase space is bounded from below by a nonzero positive quantity, which is a function only of the average number of excitations (photons) of the state. As a consequence, if this bound is violated, then the quantum state must be quantum non-Gaussian. We show that this criterion can be further generalized by considering additional Gaussian operations on the state under examination. We then apply these criteria to various non-Gaussian states evolving in a noisy Gaussian channel, proving that the bounds are violated for high values of losses, and thus also for states characterized by a positive Wigner function.
Detecting quantum non-Gaussianity via the Wigner function / M.G. Genoni, M.L. Palma, T. Tufarelli, S. Olivares, M.S. Kim, M.G.A. Paris. - In: PHYSICAL REVIEW A. - ISSN 1050-2947. - 87:6(2013), pp. 062104.1-062104.9.
|Titolo:||Detecting quantum non-Gaussianity via the Wigner function|
PARIS, MATTEO (Ultimo)
|Parole Chiave:||non-Gaussianity ; measurement theory ; quantum state engineering|
|Settore Scientifico Disciplinare:||Settore FIS/03 - Fisica della Materia|
|Data di pubblicazione:||2013|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1103/PhysRevA.87.062104|
|Appare nelle tipologie:||01 - Articolo su periodico|