How Discord underlies the Noise Resilience of Quantum Illumination

Abstract

The benefits of entanglement can outlast entanglement itself. In quantum illumination, entanglement is employed to better detect reflecting objects in environments so noisy that all entanglement is destroyed. Here, we show that quantum discord - a more resilient form of quantum correlations - explains the resilience of quantum illumination. We introduce a quantitative relation between the performance gain in quantum illumination and the amount of discord used to encode information about the presence or absence of a reflecting object. This highlights discord's role preserving the benefits of entanglement in entanglement breaking noise.

Addition of extra figure on discord flow - tracking discord's role in each step of the illumination protocol. Manuscript also revised to include further technical details. Journal reference now included