How a post-selected single photon can act like many photons - Matin Hallaji

The weak nonlinear effect of a single photon on a probe beam is studied using "weak-value amplification": by post-selecting on a rare final state (the nearly-dark port of an interferometer), we observe a phase shift per post-selected photon up to five times greater than the phase shift written by a single (non-post-selected) photon.