Null Values and Quantum State Discrimination
  We present a measurement protocol for discriminating between two different quantum states of a qubit with high fidelity. The protocol, called null value, is comprised of a projective measurement performed on the system with a small probability (also known as partial-collapse), followed by a tuned postselection. We report on an optical experimental implementation of the scheme. We show that our protocol leads to an amplified signal-to-noise ratio (as compared with a straightforward strong measurement) when discerning between the two quantum states. 
Oded Zilberberg, Alessandro Romito, David J. Starling, Gregory A.   Howland, Curtis J. Broadbent, John C. Howell, and Yuval ...
quant-ph cond-mat.mes-hall