Secure communication via quantum illumination
In the quantum illumination protocol for secure communication, Alice prepares entangled signal and idler beams via spontaneous parametric downconversion. She sends the signal beam to Bob, while retaining the idler. Bob imposes message modulation on the beam he receives from Alice, amplifies it, and sends it back to her. Alice then decodes Bobs information by making a joint quantum measurement on the light she has retained and the light she has received from him. The basic performance analysis for this protocolwhich demonstrates its immunity to passive eavesdropping, in which Eve can only listen to Alice and Bobs transmissionsis reviewed, along with the results of its first proof-of-principle experiment. Further analysis is then presented, showing that secure data rates in excess of 1Gbps may be possible over 20-km-long fiber links with technology that is available or under development. Finally, an initial scheme for thwarting active eavesdropping, in which Eve injects her own light into Bobs terminal, is proposed and analyzed.
secure communication entanglement spontaneous parametric downconversion optical parametric amplification