IEEE - Aerospace and Electronic Systems - May 2021 - 63

Daum
than pairs of photons and polarization entanglement jointly
with squeezing of the quantum vacuum and other more
general assumptions, the jury is still out. Moreover, the current analysis uses the boring old Schr€odinger equation,
whereas the correct analysis would use the Belavkin-Zakai
equation. The debate at Atlanta will be among the world's
experts in quantum radar, and we will strictly enforce the
quantum Marquess of Queensberry rules, including: no
entanglement, no squeezing, and no tunneling. Essentially,
all experts now agree that the two experiments reported
in [2] and [3] are not actually quantum radars, owing to the
amplification of the transmitted signal and the idler, and
hence, they do not offer any quantum advantage relative to
the optimal classical radar with the same transmit power,
as explained in [1], [8], and [9]. This is not debatable; it is a
mathematical fact. Some researchers think that quantum
radar today is like Wright Brothers' airplane. But for the
airplane, we had an existence theorem: Birds can fly. Also,
the Wright Brothers only required improving the engine
efficiency and lift-to-drag ratio and stability margins by
less than one order of magnitude relative to the state of the
art. In contrast, the cost of quantum radar is 10 orders of
magnitude more than optimal classical radar, and we cannot fix this problem using amplification [9]. This is not
debatable; it is a mathematical fact. But hope springs
eternal in the breasts of some quantum radar researchers,
who dream of new technology and much more general
methods of entanglement as well as new clever ideas and
new physics yet to be discovered.

MAY 2021

REFERENCES
[1] J. H. Shapiro, " The quantum illumination story, " IEEE
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[2] S. Barzanjeh, S. Pirandola, D. Vitali, and J. Fink,
" Microwave quantum illumination using a digital
receiver, " Sci. Adv., vol. 6, no. 19, 2020, Art. no. eabb0451.
[3] C. W. S. Chang, A. M. Vadiraj, J. Bourassa, B. Balaji, and
C. Wilson, " Quantum-enhanced noise radar, " Appl. Phys.
Lett., vol. 114, no. 11, Mar. 2019, Art. no. 112601.
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[6] M. Lanzagorta, Quantum Radar. San Rafael, CA, USA:
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[7] A. Cho, " The short, strange life of quantum radar, " Science, vol. 369, pp. 1556-1557, Sep. 2020.
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a

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May 2020. [Online]. Available: https://arxiv.org/abs/
2005.07116
[9] F. Daum, " Quantum radar with digital waveform gener-

IEEE A&E SYSTEMS MAGAZINE

ators, " in Proc. IEEE Radar Conf., Nov. 2020, pp. 1-6.

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https://eandt.theiet.org/content/articles/2019/04/could-quantum-radars-expose-stealth-planes https://eandt.theiet.org/content/articles/2019/04/could-quantum-radars-expose-stealth-planes https://www.arxiv.org/abs/2005.07116 https://www.arxiv.org/abs/2005.07116

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