Two-way Protocol for Quantum Cryptography with Imperfect Devices
  The security of a deterministic quantum scheme for communication, namely the LM05 [1], is studied in presence of a lossy channel under the assumption of imperfect generation and detection of single photons. It is shown that the scheme allows for a rate of distillable secure bits higher than that pertaining to BB84 [2]. We report on a first implementation of LM05 with weak pulses. 
M. Lucamarini, A. Cere', G. Di Giuseppe, S. Mancini, D. Vitali and P.   Tombesi