Two-mode squeezed states and quantum entanglement
In Chapter 2, we introduced the idea of nonclassicality and discussed at length the single-mode squeezed state. In this chapter we start with two-mode squeezed states. This discussion would naturally take us to the idea of quantum entanglement between different modes of the field. Let us denote the two modes by a and b with commutators
The two modes can correspond to different frequencies, for example to signal and idler modes in type-I parametric down-conversion or to different polarizations in type-II parametric down-conversion discussed in Section 3.10. The two modes can also correspond ...