Orthogonal Spectral Coding of Entangled Photons
Joseph M. Lukens, Amir Dezfooliyan, Carsten Langrock, M. M. Fejer, Daniel E. Leaird, Andrew M. Weiner · Physical Review Letters · 2014
We extend orthogonal optical coding, previously applied to multiuser classical communication networks, to entangled photons. Using a pulse shaper and sum-frequency generation for ultrafast coincidence detection, we demonstrate encoding and decoding of biphoton wave packets. Applying one code to the signal photon spreads the wave packet in time and creates a null at zero delay; filtering the idler with the matched code recovers a narrow correlation peak, whereas applying any other code leaves the wave packet spread. Our results could prove useful in the development of code-based quantum communication networks.