An all-fiber source of pulsed twin beams at telecom band for quantum   communication
  Motivated by the pursuit of a simple system to produce non-classical light sources for long- distance quantum communication, we generate for the first time an all-fiber source of pulsed twin beams in 1550 nm band by using a high gain fiber optical parametric amplifier. The noise of intensity difference of the twin beams is below the shot noise limit by 3.1 dB (10.4 dB after correction for losses). A detailed study reveals a number of limiting factors for higher noise reduction. Therefore, further noise reduction will be feasible once care is taken for these limiting factors. 
Xueshi Guo and Xiaoying Li and Nannan Liu and Lei Yang and Z. Y. Ou
quant-ph physics.optics