Demonstration of a Quantum Controlled-NOT Gate in the Telecom Band
  We present the first quantum controlled-NOT (CNOT) gate realized using a fiber-based indistinguishable photon-pair source in the 1.55 $\mu$m telecommunications band. Using this free-space CNOT gate, all four Bell states are produced and fully characterized by performing quantum state tomography, demonstrating the gate's unambiguous entangling capability and high fidelity. Telecom-band operation makes this CNOT gate particularly suitable for quantum information processing tasks that are at the interface of quantum communication and linear optical quantum computing. 
Jun Chen, Joseph B. Altepeter, Milja Medic, Kim Fook Lee, Burc Gokden,   Robert H. Hadfield, Sae Woo Nam, and Prem Kumar