Abstract
A central goal of any quantum technology consists in demonstrating an advantage in their performance compared to the best possible classical implementation. A quantum radar improves the detection of a target placed in a noisy environment by exploiting quantum correlations between two modes, probe and idler. The predicted quantum enhancement is not only less sensitive to loss than most quantum metrological applications, but it is also supposed to improve with additional noise. Here we demonstrate a superconducting circuit implementing a microwave quantum radar that can provide more than 20% better performance than any possible classical radar. The scheme involves joint measurement of entangled probe and idler microwave photon states after the probe has been reflected from the target and mixed with thermal noise. By storing the idler state in a resonator, we mitigate the detrimental impact of idler loss on the quantum advantage. Measuring the quantum advantage over a wide range of parameters, we find that the purity of the initial probe-idler entangled state is the main limiting factor and needs to be considered in any practical application.
This is a preview of subscription content, access via your institution
Access options
Access Nature and 54 other Nature Portfolio journals
Get Nature+, our best-value online-access subscription
$29.99 / 30 days
cancel any time
Subscribe to this journal
Receive 12 print issues and online access
$259.00 per year
only $21.58 per issue
Buy this article
- Purchase on SpringerLink
- Instant access to full article PDF
Prices may be subject to local taxes which are calculated during checkout




Similar content being viewed by others
Data availability
Data supporting the findings of this article are available at https://doi.org/10.5281/zenodo.7901142. Source data are provided with this paper.
References
Knill, E. & Laflamme, R. Power of one bit of quantum information. Phys. Rev. Lett. 81, 5672 (1998).
Datta, A., Shaji, A. & Caves, C. M. Quantum discord and the power of one qubit. Phys. Rev. Lett. 100, 050502 (2008).
Lloyd, S. Enhanced sensitivity of photodetection via quantum illumination. Science 321, 1463–1465 (2008).
Bradshaw, M. et al. Overarching framework between Gaussian quantum discord and Gaussian quantum illumination. Phys. Rev. A 95, 022333 (2017).
Shi, H., Zhang, B. & Zhuang, Q. Fulfilling entanglement’s benefit via converting correlation to coherence. Preprint at https://doi.org/10.48550/arXiv.2207.06609 (2022).
Zhang, Z., Mouradian, S., Wong, F. N. C. & Shapiro, J. H. Entanglement-enhanced sensing in a lossy and noisy environment. Phys. Rev. Lett. 114, 110506 (2015).
Xu, F. et al. Experimental quantum target detection approaching the fundamental Helstrom limit. Phys. Rev. Lett. 127, 040504 (2021).
Barzanjeh, S. et al. Microwave quantum illumination. Phys. Rev. Lett. 114, 080503 (2015).
Pirandola, S., Bardhan, B. R., Gehring, T., Weedbrook, C. & Lloyd, S. Advances in photonic quantum sensing. Nat. Photonics 12, 724–733 (2018).
Bourassa, J. & Wilson, C. M. Progress toward an all-microwave quantum illumination radar. IEEE Aerosp. Electron. Syst. Mag. 35, 58–69 (2020).
Luong, D., Balaji, B., Sandbo Chang, C. W., Ananthapadmanabha Rao, V. M. & Wilson, C. Microwave quantum radar: an experimental validation. In 2018 International Carnahan Conference on Security Technology (ICCST) 1–5 (IEEE, 2018).
Luong, D. et al. Receiver operating characteristics for a prototype quantum two-mode squeezing radar. IEEE Trans. Aerosp. Electron. Syst. 56, 2041–2060 (2020).
Chang, C. W. S., Vadiraj, A. M., Bourassa, J., Balaji, B. & Wilson, C. M. Quantum-enhanced noise radar. Appl. Phys. Lett. 114, 112601 (2019).
Barzanjeh, S., Pirandola, S., Vitali, D. & Fink, J. M. Microwave quantum illumination using a digital receiver. Sci. Adv. 6, 0451 (2020).
Livreri, P. et al. Microwave quantum radar using a Josephson traveling wave parametric amplifier. In IEEE Radar Conference (RadarConf22) 1–5 (IEEE, 2022).
Hosseiny, S. M., Norouzi, M., Seyed-Yazdi, J. & Ghamat, M. H. Engineered Josephson parametric amplifier in quantum two-modes squeezed radar. Preprint at https://doi.org/10.48550/arXiv.2205.06344 (2022).
Shapiro, J. H. The quantum illumination story. IEEE Aerosp. Electron. Syst. Mag. 35, 8–20 (2020).
Jonsson, R., Di Candia, R., Ankel, M., Ström, A. & Johansson, G. A comparison between quantum and classical noise radar sources. In 2020 IEEE Radar Conference (RadarConf20) 1–6 (IEEE, 2020).
Sorelli, G., Treps, N., Grosshans, F. & Boust, F. Detecting a target with quantum entanglement. IEEE Aerosp. Electron Syst. Mag. 37, 68–90 (2022).
Di Candia, R., Yi ğitler, H., Paraoanu, G. S. & Jäntti, R. Two-way covert quantum communication in the microwave regime. PRX Quantum 2, 020316 (2021).
Audenaert, K. M. R. et al. Discriminating states: the quantum Chernoff bound. Phys. Rev. Lett. 98, 160501 (2007).
De Palma, G. & Borregaard, J. Minimum error probability of quantum illumination. Phys. Rev. A 98, 012101 (2018).
Guha, S. & Erkmen, B. I. Gaussian-state quantum-illumination receivers for target detection. Phys. Rev. A 80, 052310 (2009).
Tan, S.-H. et al. Quantum illumination with Gaussian states. Phys. Rev. Lett. 101, 253601 (2008).
Nair, R. & Gu, M. Fundamental limits of quantum illumination. Optica 7, 771 (2020).
Zhuang, Q., Zhang, Z. & Shapiro, J. H. Entanglement-enhanced Neyman Pearson target detection using quantum illumination. J. Opt. Soc. Am. B 34, 1567–1572 (2017).
Calsamiglia, J., de Vicente, J. I., Muñoz-Tapia, R. & Bagan, E. Local discrimination of mixed states. Phys. Rev. Lett. 105, 080504 (2010).
Sanz, M., Las Heras, U., García-Ripoll, J. J., Solano, E. & Di Candia, R. Quantum estimation methods for quantum illumination. Phys. Rev. Lett. 118, 070803 (2017).
Peronnin, T., Marković, D., Ficheux, Q. & Huard, B. Sequential dispersive measurement of a superconducting qubit. Phys. Rev. Lett. 124, 180502 (2020).
Dassonneville, R., Assouly, R., Peronnin, T., Rouchon, P. & Huard, B. Number-resolved photocounter for propagating microwave mode. Phys. Rev. Appl. 14, 044022 (2020).
Dassonneville, R. et al. Dissipative stabilization of squeezing beyond 3 dB in a microwave mode. PRX Quantum 2, 020323 (2021).
Eichler, C. et al. Observation of two-mode squeezing in the microwave frequency domain. Phys. Rev. Lett. 107, 113601 (2011).
Wilson, C. M. et al. Observation of the dynamical Casimir effect in a superconducting circuit. Nature 479, 376–379 (2012).
Flurin, E., Roch, N., Mallet, F., Devoret, M. H. & Huard, B. Generating entangled microwave radiation over two transmission lines. Phys. Rev. Lett. 109, 183901 (2012).
Menzel, E. P. et al. Path entanglement of continuous-variable quantum microwaves. Phys. Rev. Lett. 109, 250502 (2012).
Bergeal, N. et al. Phase-preserving amplification near the quantum limit with a Josephson ring modulator. Nature 465, 64–68 (2010).
Bergeal, N. et al. Analog information processing at the quantum limit with a Josephson ring modulator. Nat. Phys. 6, 296–302 (2010).
Roch, N. et al. Widely tunable, nondegenerate three-wave mixing microwave device operating near the quantum limit. Phys. Rev. Lett. 108, 147701 (2012).
Flurin, E., Roch, N., Pillet, J. D., Mallet, F. & Huard, B. Superconducting quantum node for entanglement and storage of microwave radiation. Phys. Rev. Lett. 114, 090503 (2015).
Yurke, B., McCall, S. L. & Klauder, J. R. SU(2) and SU(1,1) interferometers. Phys. Rev. A 33, 4033 (1986).
Ou, Z. Y. & Li, X. Quantum SU(1,1) interferometers: basic principles and applications. APL Photonics 5, 080902 (2020).
Jonsson, R. & Ankel, M. Quantum radar – what is it good for? In 2021 IEEE Radar Conference (RadarConf21) 1–6 (IEEE, 2021).
Zhuang, Q. & Shapiro, J. H. Ultimate accuracy limit of quantum pulse-compression ranging. Phys. Rev. Lett. 128, 010501 (2022).
Reichert, M., Di Candia, R., Win, M. Z. & Sanz, M. Quantum-enhanced doppler lidar. npj Quantum Inf. 8, 147 (2022).
Chakram, S. et al. Seamless high-q microwave cavities for multimode circuit quantum electrodynamics. Phys. Rev. Lett. 127, 107701 (2021).
Julsgaard, B., Grezes, C., Bertet, P. & Mølmer, K. Quantum memory for microwave photons in an inhomogeneously broadened spin ensemble. Phys. Rev. Lett. 110, 250503 (2013).
Brady, A. J. et al. Entangled sensor-networks for dark-matter searches. PRX Quantum 3, 030333 (2022).
Bennett, C. H., Shor, P. W., Smolin, J. A. & Thapliyal, A. V. Entanglement-assisted capacity of a quantum channel and the reverse Shannon theorem. IEEE Trans. Inf. Theory 48, 2637–2655 (2002).
Hao, S. et al. Entanglement-assisted communication surpassing the ultimate classical capacity. Phys. Rev. Lett. 126, 250501 (2021).
Shi, H., Zhang, Z. & Zhuang, Q. Practical route to entanglement-assisted communication over noisy bosonic channels. Phys. Rev. Appl. 13, 034029 (2020).
Weedbrook, C., Pirandola, S., Thompson, J., Vedral, V. & Gu, M. How discord underlies the noise resilience of quantum illumination. N. J. Phys. 18, 043027 (2016).
Jo, Y. et al. Quantum illumination with asymmetrically squeezed two-mode light. Preprint at https://doi.org/10.48550/arxiv.2103.17006 (2021).
Yung, M. H., Meng, F., Zhang, X. M. & Zhao, M. J. One-shot detection limits of quantum illumination with discrete signals. npj Quantum Inf. 6, 75 (2020).
Acknowledgements
This work is part of Quantum Flagship project QMICS that has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 820505. We acknowledge the Intelligence Advanced Research Projects Activity and Lincoln Laboratories for providing a Josephson Travelling-Wave Parametric Amplifier. The devices were fabricated in the cleanrooms of ENS de Lyon, Collége de France, ENS Paris, CEA Saclay and Observatoire de Paris. We thank M. Sanz, M. Casariego, J. Govenius, J. Shapiro, P. Rouchon and D. Estève for fruitful discussions.
Author information
Authors and Affiliations
Contributions
R.A. performed the experiment and analysed the data. R.D. provided additional support for the experiment and analysis. T.P. fabricated the superconducting circuit and R.A. fabricated the target. R.A., R.D., A.B. and B.H. designed the experiment. B.H. supervised the project. All authors wrote the manuscript.
Corresponding author
Ethics declarations
Competing interests
The authors declare no competing interests.
Peer review
Peer review information
Nature Physics thanks Maxime Malnou and Quntao Zhuang for their contribution to the peer review of this work.
Additional information
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Supplementary information
Supplementary Information
Supplementary Figs. 1–7 and Sections 1–6.
Supplementary Data 1
Source data for Fig. 2 of the supplementary material.
Supplementary Data 2
Source data for Fig. 4 of the supplementary material.
Supplementary Data 3
Source data for Fig. 5 of the supplementary material.
Supplementary Data 4
Source data for Fig. 6 of the supplementary material.
Supplementary Data 5
Source data for Fig. 7 of the supplementary material.
Source data
Source Data Fig. 2
Statistical source data.
Source Data Fig. 3
Statistical source data.
Source Data Fig. 4
Statistical source data.
Rights and permissions
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
About this article
Cite this article
Assouly, R., Dassonneville, R., Peronnin, T. et al. Quantum advantage in microwave quantum radar. Nat. Phys. 19, 1418–1422 (2023). https://doi.org/10.1038/s41567-023-02113-4
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1038/s41567-023-02113-4