Demonstration of nonorthogonal multi-state discrimination below the standard quantum limit
F. E. Becerra, Jingyun Fan, G. Baumgartner, Goldhar, Jon T. Kosloski, Alan L. Migdall · 2013
We demonstrate the discrimination of four nonorthogonal states below the standard quantum limit (SQL) for a wide range of input powers, and achieving error probabilities four times lower than the SQL.