Generation of two-photon States with an arbitrary degree of entanglement via nonlinear crystal superlattices.
We demonstrate a general method of engineering the joint quantum state of photon pairs produced in spontaneous parametric down-conversion. The method makes use of a superlattice structure of nonlinear and linear materials, in conjunction with a broadband pump, to manipulate the group delays of the signal and idler photons relative to the pump pulse, and realizes photon pairs described by a joint spectral amplitude with arbitrary degree of entanglement. This method of group-delay engineering has the potential of synthesizing a broad range of states including factorizable states crucial for quantum networking and states optimized for Hong-Ou-Mandel interferometry. Experimental results for the latter case are presented, illustrating the principles of this approach.
U'Ren
Alfred B
AB
Clarendon Laboratory, Oxford University, Parks Road, Oxford, OX1 3PU, United Kingdom.
Erdmann
Reinhard K
RK
de la Cruz-Gutierrez
Manuel
M
Walmsley
Ian A
IA