Abstract
Measuring an entangled state of two particles is crucial to many quantum communication protocols. Yet Bell-state distinguishability using a finite apparatus obeying linear evolution and local measurement is theoretically limited. We extend known bounds for Bell-state distinguishability in one and two variables to the general case of entanglement in two-state variables. We show that at most classes out of hyper-Bell states can be distinguished with one copy of the input state. With two copies, complete distinguishability is possible. We present optimal schemes in each case.
- Received 1 April 2011
DOI:https://doi.org/10.1103/PhysRevA.84.022340
©2011 American Physical Society