Liquid Crystal Qubits

The generation of entangled photon pairs in liquid crystal media was first theoretically predicted by us on the basis of a model of entangled soliton pair formation [1,4]. In this approach, a liquid crystal layer can be regarded as an optical element capable of producing biphotons. The model was further developed to include nonlinear optical properties and soliton dynamics, providing estimates of spatial and temporal parameters as well as conditions for stability [2,3]. Theoretical calculations indicate that in nematic liquid crystals it is possible to realize solitary optical structures with dimensions of tens of micrometers or smaller, formation times from fractions to tens of milliseconds, and lifetimes up to hundreds of milliseconds. Of particular importance is the possibility of spatial and temporal overlap of solitons, which may be exploited for the encoding of entangled states with high selectivity. Notably, the effect, originally predicted in our theoretical works [1,4], was later experimentally confirmed by an independent research group [5]. These results suggest that liquid crystals provide a promising platform for the generation and control of entangled photon pairs with potential applications in quantum communication and quantum information processing.