Quantum communication relies on the efficient generation of entanglement between remote quantum nodes, as entanglement is required to achieve and verify secure communications1. Remote entanglement has been realized using a number of different probabilistic schemes2,3, but deterministic remote entanglement has only been demonstrated recently, using a variety of superconducting circuit approaches4,5,6. However, the deterministic violation of a Bell inequality7, a strong measure of quantum correlation, has not been demonstrated so far in a superconducting quantum communication architecture, in part because achieving sufficiently strong correlation requires fast and accurate control of the emission and capture of the entangling photons. Here, we present a simple and robust architecture for achieving this benchmark result in a superconducting system.
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The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.
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The authors thank P.J. Duda for fabrication assistance and Y. Lu and S. Chakram for helpful discussions. The authors thank MIT Lincoln Laboratory for providing a travelling-wave parametric amplifier. This effort is supported by the Army Research Office under contract W911NF-15-2-0058. Devices and experiments were also supported by the Air Force Office of Scientific Research, and by the Department of Energy (DOE). K.J.S. was supported by NSF GRFP (NSF DGE-1144085). É.D. was supported by LDRD funds from Argonne National Laboratory. A.N.C. was supported in part by the DOE, Office of Basic Energy Sciences. D.I.S. acknowledges support from the David and Lucile Packard Foundation. This work was partially supported by the UChicago MRSEC (NSF DMR-1420709) and made use of the Pritzker Nanofabrication Facility, which receives support from SHyNE, a node of the National Science Foundation’s National Nanotechnology Coordinated Infrastructure (NSF NNCI-1542205). The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of the Army Research Laboratory or the US Government.
The authors declare no competing interests.
Journal peer review information: Nature Physics thanks Nicolas Sangouard and the other anonymous reviewer(s) for their contribution to the peer review of this work.
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Zhong, Y.P., Chang, HS., Satzinger, K.J. et al. Violating Bell’s inequality with remotely connected superconducting qubits. Nat. Phys. 15, 741–744 (2019). https://doi.org/10.1038/s41567-019-0507-7
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