Microwave quantum diode

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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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Nature Communications, Volume 15, issue 1
The fragile nature of quantum circuits is a major bottleneck to scalable quantum applications. Operating at cryogenic temperatures, quantum circuits are highly vulnerable to amplifier backaction and external noise. Non-reciprocal microwave devices such as circulators and isolators are used for this purpose. These devices have a considerable footprint in cryostats, limiting the scalability of quantum circuits. As a proof-of-concept, here we report a compact microwave diode architecture, which exploits the non-linearity of a superconducting flux qubit. At the qubit degeneracy point we experimentally demonstrate a significant difference between the power levels transmitted in opposite directions. The observations align with the proposed theoretical model. At − 99 dBm input power, and near the qubit-resonator avoided crossing region, we report the transmission rectification ratio exceeding 90% for a 50 MHz wide frequency range from 6.81 GHz to 6.86 GHz, and over 60% for the 250 MHz range from 6.67 GHz to 6.91 GHz. The presented architecture is compact, and easily scalable towards multiple readout channels, potentially opening up diverse opportunities in quantum information, microwave read-out and optomechanics.
Funding Information: We acknowledge the financial support from Academy of Finland grants (grant number 297240, 312057 and 303677), and from the European Union’s Horizon 2020 research and innovation programme under the European Research Council (ERC) programme (grant number 742559) and Marie Sklodowska-Curie actions (grant agreements 766025). We sincerely recognize the provision of facilities by Micronova Nanofabrication Centre, and OtaNano - Low Temperature Laboratory of Aalto University which is a part of European Microkelvin Platform EMP (grant number. 824109), to perform this research. We thank and acknowledge VTT Technical Research Center for provision of high quality sputtered Nb films. | openaire: EC/H2020/742559/EU//SQH | openaire: EC/H2020/766025/EU//QuESTech
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Upadhyay, R, Golubev, D S, Chang, Y C, Thomas, G, Guthrie, A, Peltonen, J T & Pekola, J P 2024, ' Microwave quantum diode ', Nature Communications, vol. 15, no. 1, 630 . https://doi.org/10.1038/s41467-024-44908-w