We present two hyperconcentration protocols for hyperentangled states, in which entanglement occurs simultaneously in the polarization and the spatial degrees of freedom. One uses an auxiliary single photon prepared in a fixed state. The other uses two less-entangled photon pairs. In both schemes, a two photon maximally hyperentangled state can be obtained from the nonmaximally entangled states with a certain success probability. The procrustean concentration is realized by polarizing beam splitters and nondestructive quantum nondemolition detection. In both protocols the unsuccessful instances can be reconcentrated repeatedly to get a higher success probability, which makes our schemes efficient and useful in quantum information processing.
© 2013 Optical Society of America
Original Manuscript: June 10, 2013
Manuscript Accepted: August 26, 2013
Published: October 2, 2013
Xi-Han Li, Xiao Chen, and Zhi Zeng, "Hyperconcentration for entanglement in two degrees of freedom," J. Opt. Soc. Am. B 30, 2774-2780 (2013)