All-optical superconducting qubit readout

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Journal Article | Published | English

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Abstract
The rapid development of superconducting quantum hardware is expected to run into substantial restrictions on scalability because error correction in a cryogenic environment has stringent input–output requirements. Classical data centres rely on fibre-optic interconnects to remove similar networking bottlenecks. In the same spirit, ultracold electro-optic links have been proposed and used to generate qubit control signals, or to replace cryogenic readout electronics. So far, these approaches have suffered from either low efficiency, low bandwidth or additional noise. Here we realize radio-over-fibre qubit readout at millikelvin temperatures. We use one device to simultaneously perform upconversion and downconversion between microwave and optical frequencies and so do not require any active or passive cryogenic microwave equipment. We demonstrate all-optical single-shot readout in a circulator-free readout scheme. Importantly, we do not observe any direct radiation impact on the qubit state, despite the absence of shielding elements. This compatibility between superconducting circuits and telecom-wavelength light is not only a prerequisite to establish modular quantum networks, but it is also relevant for multiplexed readout of superconducting photon detectors and classical superconducting logic.
Publishing Year
Date Published
2025-03-01
Journal Title
Nature Physics
Publisher
Springer Nature
Acknowledgement
We thank F. Hassani and M. Zemlicka for assistance with qubit design and high-power readout, respectively, and P. Winkel and I. Pop at Karlsruhe Institute of Technology for providing the JPA. This work was supported by the European Research Council under grant nos. 758053 (ERC StG QUNNECT) and 101089099 (ERC CoG cQEO), and the European Union’s Horizon 2020 research and innovation program under grant no. 899354 (FETopen SuperQuLAN). This research was funded in whole, or in part, by the Austrian Science Fund (FWF) DOI 10.55776/F71. L.Q. acknowledges generous support from the ISTFELLOW programme and G.A. is the recipient of a DOC fellowship of the Austrian Academy of Sciences at IST Austria. Open access funding provided by Institute of Science and Technology (IST Austria).
Volume
21
Article Number
9470
ISSN
eISSN
IST-REx-ID
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Creative Commons Attribution 4.0 International Public License (CC-BY 4.0):
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OA Open Access
Date Uploaded
2025-04-16
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