Polarization entanglement purification using spatial entanglement

Phys Rev Lett. 2002 Dec 16;89(25):257901. doi: 10.1103/PhysRevLett.89.257901. Epub 2002 Dec 2.

Abstract

We present a scheme for entanglement purification with linear optics that works for currently available parametric down-conversion sources, in contrast to a previous scheme [J. W. Pan, Nature (London) 410, 1067 (2001)]] that relied on ideal single-pair sources. The present scheme makes use of spatial entanglement in order to purify polarization entanglement. Surprisingly, spatial entanglement as an additional resource also leads to a substantial improvement in entanglement output compared to the previous scheme.