Optical Bell-state analysis in the coincidence basis
Stephen Patrick Walborn, W. A. T. Nogueira, Sebastião Pádua, Carlos Henrique Monken · Europhysics Letters (EPL) · 2003
Many quantum information protocols require a Bell-state measurement of entangled systems. Most optical Bell-state measurements utilize two-photon interference at a beam splitter. By creating polarization-entangled photons with spontaneous parametric down-conversion using a first-order Hermite-Gaussian pump beam, we invert the usual interference behavior and perform an incomplete Bell-state measurement in the coincidence basis. We discuss the possibility of a complete Bell-state measurement in the coincidence basis using hyperentangled states ( Phys. Rev. A, 58 (1998) R2623).