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Quantum advantage in microwave quantum radar


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.

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Fig. 1: Quantum radar principle and implementation.
Fig. 2: Tuning up the interferometer.
Fig. 3: Observation of a quantum advantage for a microwave radar.
Fig. 4: Quantum advantage sensitivity to parameters.

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Data supporting the findings of this article are available at Source data are provided with this paper.


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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.

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Authors and Affiliations



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.

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Correspondence to B. Huard.

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Nature Physics thanks Maxime Malnou and Quntao Zhuang for their contribution to the peer review of this work.

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Supplementary Figs. 1–7 and Sections 1–6.

Supplementary Data 1

Source data for Fig. 2 of the supplementary material.

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Source data for Fig. 4 of the supplementary material.

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Source data for Fig. 5 of the supplementary material.

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Source data for Fig. 6 of the supplementary material.

Supplementary Data 5

Source data for Fig. 7 of the supplementary material.

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Source Data Fig. 2

Statistical source data.

Source Data Fig. 3

Statistical source data.

Source Data Fig. 4

Statistical source data.

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Assouly, R., Dassonneville, R., Peronnin, T. et al. Quantum advantage in microwave quantum radar. Nat. Phys. 19, 1418–1422 (2023).

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