Increasing the Visibility of Multiphoton Entanglement
Matteo G. A. Paris · Fortschritte der Physik · 2000
The entanglement between the two beams exiting a Mach-Zehnder interferometer fed two squeezed states involves many photons. We evaluate the degree of this multiphoton entanglement in terms of the excess entropy of the pure state at the output. A novel kind of fourth-order correlation function based on homodyne detection is suggested to reveal entanglement. Apart from the very low signals regime homodyne-like detection shows a higher fringes visibility than the measurement of the coincidence counting rate.