The short weird life—and potential afterlife—of quantum radar

David Luong, Bhashyam Balaji, Sreeraman Rajan

Quantum radar is a fledgling new technology that promises gains in detection performance. However, there are challenges standing in the way of their implementation. In this article, three classes of quantum radars are discussed: quantum interferometric radar, quantum illumination radar, and quantum two-mode squeezing (QTMS) radar. Of these, the last-named is the closest to being implemented in real life, though it is by no means the last word on the subject. In conclusion, we find that quantum radars are at least worth studying further.

Jeffrey H. Shapiro

The Internet is agog with stories about quantum radar. Will it really make stealth aircraft vulnerable? Were the microwave experiments reported in 2020 from Europe and Canada really proof-of-principle laboratory demonstrations of quantum radar's advantage over classical radar? Or, does the 25 September 2020 news article in Science-entitled "The short, strange life of quantum radar"-paint the true picture? This paper disentangles microwave quantum radar's alphabet soup: quantum illumination (QI) radar, quantum illumination with a microwave parametric amplifier receiver (QI-MPA) radar, quantum-correlated noise (QCN) radar, and quantum-correlated noise radar with a correlation receiver (QCN-CR). In particular, it evaluates-with no explicit quantum-mechanical notation or calculations-these radars' miss probabilities at fixed false-alarm probability and it compares them to those for classical radar's relevant alphabet soup, viz., coherent-state homodyne (CS-Hom) radar, coherent-state heterodyne (CS-Het) radar, classically-correlated noise (CCN) radar, and classically-correlated noise radar with a correlation receiver (CCN-CR). These comparisons show that, under ideal operating conditions, the QI and QI-MPA radars offer performance advantages over their best classical counterparts. Moreover, QI-MPA's advantage is similar to that for its error-probability exponent when target absence and presence are equally likely and all radars make minimum error-probability decisions based on their respective measurements. Available theory, however, is unable to fully quantify QI's advantage in the operating regime of interest. Ultimately-after accounting for problems that afflict QI and QI-MPA, but not their classical competitors, and factoring in realistic standoff-sensing parameters-it will be concluded that the aforementioned Science article has it correct. QI target detection has little to offer for standoff sensing, i.e., it does not compromise stealth aircraft.

Marco O. Lanzagorta

Ivan B. Djordjević

Ingemar T. Ernberg, Göran Johansson, Tomas Lindblad +2 more