Efficient Bell state analyzer for time-bin qubits with fast-recovery WSi   superconducting single photon detectors
  We experimentally demonstrate a high-efficiency Bell state measurement for time-bin qubits that employs two superconducting nanowire single-photon detectors with short dead-times, allowing projections onto two Bell states, |Psi>- and |Psi+>. Compared to previous implementations for time-bin qubits, this yields an increase in the efficiency of Bell state analysis by a factor of thirty. 
Raju Valivarthi, Itzel Lucio-Martinez, Allison Rubenok, Philip Chan,   Francesco Marsili, Varun B.Verma, Matthew D.Shaw, J.A...
quant-ph