OPTIMAL DETERMINISTIC ENTANGLEMENT CONCENTRATION OF POLARIZED PHOTONS THROUGH DIRECT SUM EXTENSION AND CAVITY-ASSISTED INTERACTION
A scheme for optimal deterministic entanglement concentration is proposed, and its corresponding optical realization based on a cavity-assisted linear optical system is presented. In this scheme, the quantum circuit devised is simpler than that built in [Y. J. Gu, et al. (2006), Phys. Rev. A. 73, 022321], as it requires the minimum ancillary dimensions and the number of unitary operations. Moreover, we show that, by introducing a path-polarization entanglement state based on the direct sum extension method, three elementary controlled phase-flip gates between two photons are sufficient in the design of its optical realization scheme, making it easy to be implemented from the experimental point of view. Meanwhile, the scheme is verified effective to recover highly entangled pairs from mixed states.
entanglement concentration direct sum extension optical realization path-polarization entanglement state