Friday, April 24, 2026

Quantum Radar Finds an Infrastructure Path While the Stealth Mission Fades


Quantum Radar for ISAC: Sum-Rate Optimization

Emerging Technology — Sensing & Spectrum

A new IEEE paper embedding entangled-photon sensing in a 6G base station shows where quantum illumination can actually earn its keep — and it is not chasing F-22s.

By Stephen Pendergast  Senior Life Member, IEEE |  April 24, 2026

Bottom Line Up Front 

A peer-reviewed architecture published this month in IEEE Transactions on Communications by Alsaui et al. embeds a quantum two-mode squeezed vacuum (TMSV) radar into a full-duplex base station and claims a 21.2% communication sum-rate gain (+15.9 Gbps) over a conventional Integrated Sensing and Communications (ISAC) baseline while meeting identical detection requirements. The result is technically credible but operationally narrow: the simulated dwell time is roughly 500 seconds and the operating frequency is 16 GHz — parameters that rule out moving targets and airborne platforms, but fit fixed-site wireless infrastructure being standardized for 6G. The announcement lands against a contrasting backdrop: DARPA’s Robust Quantum Sensors (RoQS) program is now pushing quantum sensors onto DoD platforms for navigation and ISR; China has publicized mass production of a four-channel single-photon detector for counter-stealth applications; and leading theorists including MIT’s Jeffrey H. Shapiro continue to caution that long-range quantum radar against aircraft remains, in his words, “severely limited” in utility. The near-term payoff for quantum illumination is now clearly an infrastructure and short-range sensing story — not an anti-stealth silver bullet.

The IEEE Result

Abdulmohsen Alsaui and colleagues at Memorial University of Newfoundland, IIT Delhi, the University of Michigan and Kyung Hee University formalize what they call an Integrated Quantum Sensing and Classical Communication (IQSCC) architecture.[1] A multi-antenna, full-duplex base station simultaneously serves one downlink user, receives from one uplink user, and pings a monostatic target using a TMSV quantum radar waveform. The communication function remains entirely classical; only the sensing channel is quantum.

The value proposition rests on a single physical fact: in high-thermal-noise, low-signal-power regimes, entangled signal-idler photon pairs yield a provable detection advantage over any classical scheme of equal energy — up to 6 dB in the Helstrom ideal limit, and a practically achievable 3 dB with a correlation receiver.[1][2] That 3 dB relaxation of the radar SINR floor frees transmit power from sensing that can be reallocated to the communication beam. The authors formulate this as a non-convex sum-rate maximization over transmit beamforming vectors, radar covariance and uplink power, solving it via successive convex approximation. At their operating point — 16 GHz, 4 GHz bandwidth, 10×10 antennas at the base station, Pf=10−6, Pd=0.99 — the classical coherent-state radar requires 14 dB SINR while the quantum TMSV variant needs only 11 dB, lifting sum rate from roughly 75 Gbps to 91 Gbps.[1]

The paper builds directly on the classical FD-ISAC framework of He et al.,[3] published in the same IEEE journal family in 2023, which established the joint beamforming and power optimization methodology for full-duplex base stations performing simultaneous sensing and two-way communication. The IQSCC work inherits that optimization structure and swaps in a quantum detection constraint derived from the statistical detection theory of quantum illumination.

Why This Is Not an Anti-Stealth Weapon

The catch is in the photon accounting. The quantum advantage is maximized only when the mean photon number per temporal-spectral mode is well below unity — roughly 0.5 photons per mode in the paper’s configuration. Total transmitted power in the reference design is about 21 femtowatts, distributed across roughly 2×1012 independent modes generated by spreading a 4 GHz-bandwidth TMSV source over a dwell time of approximately 502 seconds.[1] A vehicle at highway speed would cover more than eight miles during a single coherent integration. For automotive radar, airborne fire-control, or missile terminal sensing, the scene stationarity assumption collapses instantly.

This is the same constraint flagged by MIT’s Jeffrey H. Shapiro, who co-authored the foundational Gaussian quantum illumination papers and has since become the field’s most rigorous skeptic. In his widely cited review “The Quantum Illumination Story,” Shapiro concluded that entangled-photon radar does deliver a real advantage on an entanglement-breaking channel — but that “a realistic assessment of that improvement’s utility…shows that its value is severely limited.”[2] In a 2020 Science magazine feature surveying the field, Shabir Barzanjeh of the University of Calgary put it more bluntly: “If you crank up the power, you won’t see any difference between the quantum and the classical.”[4] Fabrice Boust of ONERA, the French aerospace research agency, told the same publication that quantum radar “will never be deployed for long-range uses such as tracking airplanes.”[4]

The fundamental reason is geometric. At microwave frequencies, beams are far less collimated than optical beams, imposing severe round-trip path loss. The low-photon regime required for the quantum advantage therefore collides head-on with the photon budget required to see a small radar cross-section at operationally useful range. Karsa, Sorelli and other theorists have shown the quantum advantage shrinks rapidly as transmissivity drops below roughly −60 dB — a regime reached well inside 10 km for typical airborne targets.[5][6]

The Experimental Benchmark

The most rigorous experimental validation of microwave quantum radar to date came from Réouven Assouly and collaborators at ENS de Lyon and CNRS, published in Nature Physics in June 2023. Their superconducting-circuit implementation demonstrated a joint probe-idler measurement with more than 20% better detection performance than the best possible classical radar of equivalent energy — a true quantum advantage Q > 1.[7][8] The experiment lives inside a dilution refrigerator and operates on a target at proof-of-principle scale, but it is the first microwave result to close the experimental loop between Lloyd’s 2008 proposal and a measurable laboratory advantage.

A parallel line at the University of Waterloo’s Institute for Quantum Computing, in collaboration with Defence Research and Development Canada, demonstrated quantum two-mode squeezing radar at around 5 GHz using Josephson parametric converters — the same frequency band used by Wi-Fi and cellular systems.[9] Earlier proof-of-concept work by Barzanjeh et al. in Science Advances (2020) demonstrated free-space quantum illumination at 1 meter range at room temperature using a digital phase-conjugate receiver.[10]

Hardware is improving on the source side. Patrizia Livreri of the University of Palermo, in an IEEE AESS Distinguished Lecture in August 2025, laid out the path from today’s Josephson Parametric Amplifier (JPA) sources to Josephson Traveling-Wave Parametric Amplifiers (JTWPA), which offer higher bandwidth — reported up to 4 GHz — and a more practical pathway toward X-band operation.[11] The IQSCC paper relies explicitly on this class of source to achieve its mode count.

The Policy and Program Backdrop

The U.S. Defense Advanced Research Projects Agency formally launched Phase 1 of its Robust Quantum Sensors (RoQS) program in August 2025, aimed at transitioning quantum sensors from controlled laboratory conditions onto moving military platforms.[12][13] RoQS targets magnetic, electric-field, acceleration, rotation and gravity sensing — primarily for alternative positioning, navigation and timing (PNT) and intelligence, surveillance and reconnaissance (ISR) roles — rather than radar per se. Lockheed Martin and Q-CTRL are partnered on quantum-enabled inertial navigation under the program.[14] John Burke, principal director for quantum science in the Office of the Under Secretary of Defense for Research and Engineering, said in 2024 that quantum sensing is considered “the most mature” quantum application for near-term DoD use.[15]

DARPA’s complementary Quantum Apertures program pursues Rydberg-atom RF receivers — a distinct quantum technique aimed at sensitivity and frequency agility for electromagnetic spectrum operations, radar and communications receiver chains.[16] Quantum radar transmission itself does not appear in any named U.S. program of record.

The People’s Republic of China has taken a more public posture. In October 2025, the Quantum Information Engineering Technology Research Centre in Anhui province announced mass production of a four-channel single-photon detector described as a “photon catcher,” reportedly achieving 35% detection efficiency at operating temperatures down to −120 °C.[17][18] Chinese state media framed the detector as enabling quantum radar networks capable of detecting low-observable aircraft. State-owned CETC first claimed a 100 km quantum radar detection milestone in 2016; those claims remain independently unverified and are treated with skepticism by Western experts, including Shapiro and Huard.[4][19] Heather Penney of the Mitchell Institute for Aerospace Studies has argued in a January 2024 paper that quantum radar’s real-world performance remains “unreliable” owing to decoherence, low photon return rates and environmental noise.[20]

Where ISAC Actually Lives

ISAC itself — quantum or classical — is no longer speculative. At the 3GPP RAN #108 meeting in June 2025, ISAC was formally added to the scope of study for 6G radio, establishing it as a “Day 1” feature for the next-generation standard.[21] The European Telecommunications Standards Institute’s Industry Specification Group on ISAC is developing pre-standardization KPIs and channel models.[22] Ericsson, Huawei, Nokia and Samsung have all published ISAC architectural roadmaps targeting centimeter-level localization, radar-like base station functions and drone detection as anchor use cases.[22][23] 5G Americas, in an August 2025 white paper, explicitly identifies defense drone detection among the high-value ISAC applications driving 6G adoption.[24]

The U.S. Department of Defense has invested in the military ISAC application directly. The Office of the Under Secretary of Defense’s FutureG program sponsored an April 2025 national workshop at George Mason University on ISAC, with an explicit mission to “exploit the RF environment by utilizing existing and emerging communication networks, including 5G/6G and tactical radios, as dynamic sensing platforms.”[25] NATO’s IST-220 research task group is working the same problem from the alliance side, with a dedicated panel on non-terrestrial networks and ISAC scheduled for the IEEE MILCOM 2025 conference.[26]

Into this standardization current, the Alsaui et al. result offers a specific value proposition: if a fixed base station already has the full-duplex radio, the phased array, and a compliant 6G waveform, bolting a cryogenic TMSV source alongside a classical transmit chain buys a measurable communication-throughput gain under a fixed sensing requirement — at the cost of cryogenics, long dwell, and applicability only to effectively stationary targets in the cell.

What Quantum ISAC Could Plausibly Do

The realistic near-term applications for the IQSCC architecture cluster at the intersection of fixed infrastructure and benign kinematics. Industrial IoT sensing inside factories, presence detection in smart buildings, asset tracking across warehouse floors, slow-UAS hover detection around critical infrastructure, and perimeter monitoring all feature stationarity intervals measured in seconds to minutes — compatible with the long dwell times the quantum advantage demands. In those scenarios, picowatt-level transmit power also yields an incidental low-probability-of-intercept property that may attract interest for covert surveillance in contested environments.

Short-range biomedical imaging is a separate non-radar application line that shares the same underlying physics, explored in Science Advances[10] and in follow-on work led by York University, MIT and the University of Camerino in 2024.[27] Unlike the radar mission, the biomedical case operates at standoff distances of centimeters to meters, where photon budget is not the limiting factor.

Fixed-site air defense surveillance, space domain awareness against slow orbital debris, and augmentation of over-the-horizon radar remain theoretical candidates where the dwell-time penalty is tolerable, but no program of record in any NATO country currently funds them.

The Honest Assessment

The Alsaui paper advances the quantum ISAC literature by being the first to treat quantum radar as a sensing subsystem inside a realistic 6G base station design rather than as a standalone detection concept. Its mathematical contributions — particularly the ROC-to-SINR mapping that lets quantum detection physics plug into conventional radar engineering workflow — are durable regardless of whether a particular hardware generation succeeds in the field. But its performance claims sit on top of an operating envelope defined by low photon numbers, high thermal backgrounds, microwave frequencies between roughly 3 and 30 GHz, and coherent integration intervals measured in minutes.

Quantum radar, in the shape Lloyd proposed in 2008, is not the technology that will detect a B-21 on its approach or an F-35 in a SEAD mission. The theorists who built the field say so openly, and the physics bears them out. But the same physics supports a useful, bounded role for entangled microwaves inside the next generation of communications infrastructure — and it is that infrastructure role, not the counter-stealth role, that the serious engineering papers are now optimizing toward.

Stephen Pendergast is a retired senior radar systems engineer (Lynx SAR/GMTI, AMASS/ACME) and IEEE Senior Life Member based in San Diego. He writes on defense, aerospace and emerging sensor technologies.

Sources

  1. Alsaui, A., Dobre, O. A., Kundu, N. K., Hariri, A., and Shin, H., “Quantum Radar for ISAC: Sum-Rate Optimization,” IEEE Transactions on Communications, Vol. 74, pp. 7329–7341, 2026. DOI: 10.1109/TCOMM.2026.3681651.
  2. Shapiro, J. H., “The Quantum Illumination Story,” IEEE Aerospace and Electronic Systems Magazine, Vol. 35, No. 4, pp. 8–20, April 2020. arXiv preprint: https://arxiv.org/abs/1910.12277
  3. He, Z., Xu, W., Shen, H., Ng, D. W. K., Eldar, Y. C., and You, X., “Full-Duplex Communication for ISAC: Joint Beamforming and Power Optimization,” IEEE Journal on Selected Areas in Communications, Vol. 41, No. 9, pp. 2920–2936, September 2023. https://doi.org/10.1109/JSAC.2023.3287540
  4. Cho, A., “The short, strange life of quantum radar,” Science, Vol. 369, Issue 6511, pp. 1556–1557, 23 September 2020. https://www.science.org/doi/10.1126/science.369.6511.1556
  5. Karsa, A., and Pirandola, S., “Energetic considerations in quantum target ranging,” 2021 IEEE Radar Conference (RadarConf21), IEEE, 2021.
  6. Sorelli, G., Treps, N., Grosshans, F., and Boust, F., “Detecting a target with quantum entanglement,” IEEE Aerospace and Electronic Systems Magazine, Vol. 37, No. 5, pp. 68–90, May 2022.
  7. Assouly, R., Dassonneville, R., Peronnin, T., Bienfait, A., and Huard, B., “Quantum advantage in microwave quantum radar,” Nature Physics, Vol. 19, pp. 1418–1422, October 2023. https://www.nature.com/articles/s41567-023-02113-4
  8. Assouly, R., et al., “Demonstration of Quantum Advantage in Microwave Quantum Radar,” arXiv:2211.05684. https://arxiv.org/abs/2211.05684
  9. Institute for Quantum Computing, University of Waterloo, “Quantum illuminates new potential for radar technology,” 21 May 2024. https://uwaterloo.ca/institute-for-quantum-computing/news/quantum-illuminates-new-potential-radar-technology
  10. Barzanjeh, S., Pirandola, S., Vitali, D., and Fink, J. M., “Microwave quantum illumination using a digital receiver,” Science Advances, Vol. 6, No. 19, eabb0451, May 2020. https://www.science.org/doi/10.1126/sciadv.abb0451
  11. Livreri, P., “Towards a Long-Range Microwave Quantum Radar,” IEEE Aerospace and Electronic Systems Society Distinguished Lecture, 19 August 2025. https://ieee-aess.org/presentation/webinar/towards-long-range-microwave-quantum-radar
  12. DARPA, “From fragile to field-ready: RoQS program launches first phase,” news release, 27 August 2025. https://www.darpa.mil/news/2025/roqs-launches-first-phase
  13. DARPA, “Taking quantum sensors out of the lab and into defense platforms,” news release, 7 February 2025. https://www.darpa.mil/news/2025/quantum-sensors-defense-platforms
  14. Lockheed Martin, “Lockheed Martin and Q-CTRL: Revolutionizing Navigation with Quantum Technology,” 27 August 2025. https://www.lockheedmartin.com/en-us/news/features/2025/lockheed-martin-Q-CTRL-revolutionizing-navigation-with-quantum-technology.html
  15. Martin, B., “DARPA eyeing new quantum sensing program,” DefenseScoop, 30 December 2024. https://defensescoop.com/2024/12/30/darpa-eying-new-quantum-sensing-program-robust-quantum-sensors-roqs/
  16. DARPA, “Quantum Apertures (QA) Program,” official program page. https://www.darpa.mil/research/programs/quantum-apertures
  17. Army Recognition Group, “Discover why China bets on quantum radar to cancel the F-22 and F-35 stealth advantage,” 21 October 2025. https://www.armyrecognition.com/news/aerospace-news/2025/discover-why-china-bets-on-quantum-radar-to-cancel-the-f-22-and-f-35-stealth-advantage
  18. Asia Times, “Stealth buster? China touts next-gen, quantum radar tech,” 17 October 2025. https://asiatimes.com/2025/10/stealth-buster-china-touts-next-gen-quantum-radar-tech/
  19. Hill, G., “Quantum Radar: Implications for Canadian Defence,” Canadian Forces College National Security Programme paper, 2022.
  20. Penney, H., “The Myth of the Quantum Radar ‘Holy Grail’,” Mitchell Institute for Aerospace Studies, Policy Paper Vol. 45, January 2024.
  21. Samsung Research Blog, “Integrated Sensing and Communication (ISAC): New monetization opportunities for 5G and beyond,” December 2025, referencing 3GPP RAN #108 (June 2025). https://research.samsung.com/blog/Integrated-Sensing-and-Communication-ISAC-New-monetization-opportunities-for-5G-and-beyond
  22. Tiami Networks, “The State of Integrated Sensing (ISAC) in 5G Standards,” 14 May 2025, covering ETSI ISG ISAC and 3GPP activity. https://tiaminetworks.com/the-state-of-integrated-sensing-isac-in-5g-standards/
  23. Ericsson, “ISAC: Integrated Sensing and Communication,” June 2024. https://www.ericsson.com/en/blog/2024/6/integrated-sensing-and-communication
  24. 5G Americas, “Transforming Industries with Integrated Sensing and Communication,” white paper, August 2025. https://www.5gamericas.org/transforming-industries-with-integrated-sensing-and-communication/
  25. U.S. Department of Defense, Office of the Under Secretary of Defense for Research and Engineering, “May 2025 Integrated Sensing and Communications Report” (proceedings of the April 2025 George Mason University ISAC Workshop). https://rt.cto.mil/wp-content/uploads/2025/07/ISAC-Report-from-Apr-2025-Workshop.pdf
  26. DoD FutureG program, “Integrated Sensing and Communications (ISAC),” program priorities page. https://rt.cto.mil/ddre-rt/science-and-technology-futures/futureg-home/priorities/integrated-sensing-and-communications-isac/
  27. IEEE MILCOM 2025 Conference, Panel PAN-09: “Non-Terrestrial Networks & ISAC: Extending 5G Into the Battlespace,” NATO IST-220. https://milcom2025.ieee-milcom.org/pan-09-non-terrestrial-networks-isac-extending-5g-battlespace
  28. The Quantum Insider, “Quantum Illumination Lights up Potential Path to Medical Imaging And Radar That Can Operate in Noisy Environments,” 5 November 2024, summarizing collaboration of York University, MIT and University of Camerino. https://thequantuminsider.com/2024/11/05/quantum-illumination-lights-up-potential-path-to-medical-imaging-and-radar-that-can-operate-in-noisy-environments/

 

A. Alsaui, O. A. Dobre, N. K. Kundu, A. Hariri and H. Shin, "Quantum Radar for ISAC: Sum-Rate Optimization," in IEEE Transactions on Communications, vol. 74, pp. 7329-7341, 2026, doi: 10.1109/TCOMM.2026.3681651.

Abstract: Integrated sensing and communication (ISAC) is emerging as a key enabler for spectrum-efficient and hardware-converged wireless networks. However, classical radar systems within ISAC architectures face fundamental limitations under low signal power and high-noise conditions. This paper proposes a novel framework that embeds quantum illumination radar into a base station to simultaneously support full-duplex classical communication and quantum-enhanced target detection. The resulting integrated quantum sensing and classical communication (IQSCC) system is optimized via a sum-rate maximization formulation subject to radar sensing constraints. The non-convex joint optimization of transmit power and beamforming vectors is tackled using the successive convex approximation technique. Furthermore, we derive performance bounds for classical and quantum radar protocols under the statistical detection theory, highlighting the quantum advantage in low signal-to-interference-plus-noise ratio regimes. Simulation results demonstrate that the proposed IQSCC system achieves a higher communication throughput than the conventional ISAC baseline while satisfying the sensing requirement.
keywords: {Sonar;Antennas;Transmitting antennas;Receiving antennas;Propagation losses;Electromagnetic propagation;Feeds;Antennas and propagation;Thermal noise;System-on-chip;Full-duplex (FD) communication;integrated sensing and communication (ISAC);quantum illumination (QI);quantum radar},


URL: https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11477857&isnumber=11320979


 

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Quantum Radar Finds an Infrastructure Path While the Stealth Mission Fades

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