Abstract

We show that a anti-correlation of a Stokes parameter implies polarization entanglement according to the PPT criterion and analyze an experiment underway to make a bright source of entangled photons using polarization squeezed light. The polarization of light can be analyzed by using either the continuous variable (CV) or the discrete variable (DV) formalism. We demonstrate that it is possible to develop both approaches by using the second order correlation tensor $R_{kl,nm}^{(2)}(\tau )=〈{\widehat{a}}_k^{†}(t){\widehat{a}}_l^{†}(t+\tau ){\widehat{a}}_m(t+\tau ){\widehat{a}}_n(t)〉$, where â_j (with j={H, V}) are the operators associated to orthogonal polarization modes. Considering continuous variables, one can express the correlation function of one of the Stokes parameters in terms of $R_{kl,mn}^{(2)}(\tau )$. On the other hand, we show that, if we extract two photons from the investigated state, the density matrix associated to them will be proportional to the second order correlation tensor.

© 2011 IEEE