Photon Number Resolution Enables Quantum Receiver for Realistic Coherent Optical Communications
Francisco E. Becerra Chavez, Jingyun Fan, Alan L. Migdall
Quantum-enhanced measurements can provide information about the properties of a physical system with sensitivities beyond what is fundamentally possible with conventional technologies. However, this advantage can be achieved only if quantum measurement technologies are robust against losses and realistic imperfections. Here we demonstrate a robust quantum receiver for the coherent communication channel that extends its performance beyond the standard quantum limit (SQL) from the few-photons regime to the high-input-power regime. This receiver is based on adaptive measurements and photon number resolution providing high sensitivity and robustness against imperfections, and shows the greatest advantage over the SQL ever achieved by any quantum receiver at power levels compatible with state-of-the-art optical communication systems bringing quantum receivers closer to realistic applications.