Si-Hui Tan, Leonid A. Krivitsky, Berthold-Georg Englert
The variance of difference of photocounts is an established measure of quantum correlations for quantum states of light. It enables us to discriminate between the classical correlation of a two-mode coherent state and the quantum correlation of a twin-beam state. We study the effect of loss and saturation of the photon-number-resolving detector on the measurement of the variance of difference of photocounts. An analytic function is derived for this variance, both for the coherent and the twin-beam states. It is found that the variance of difference of photocounts is no longer a reliable entanglement measure in the non-linear regime of the detector response but it remains useful in some range of values of average photon numbers of the incident light. We also quantify the linear regime of the detector with saturation which will be useful for calibration of the detector quantum efficiency.
View original:
http://arxiv.org/abs/1210.8022
No comments:
Post a Comment