Wideband Isolation by Frequency Conversion in a Josephson-Junction Transmission Line

Leonardo Ranzani, Shlomi Kotler, Adam J. Sirois, Michael P. Defeo, Manuel Castellanos-Beltran, Katarina Cicak, Leila R. Vale, José Aumentado

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


Nonreciprocal transmission and isolation at microwave frequencies are important in many practical applications. In particular, compact isolators are useful in protecting sensitive quantum circuits operating at cryogenic temperatures from amplifier backaction and other environmental noise such as black-body radiation from higher temperature stages. However, the size of commercial cryogenic isolators limits the ability to measure multiple quantum circuits because of space constraints in typical dilution refrigerator systems. Furthermore, isolators usually require the use of ferrite components that cannot be integrated at the chip level and, since they also need large biasing magnetic fields, are incompatible with superconducting quantum circuits. In this work we show one way to accomplish isolation in a superconducting chip-scale device, a traveling-wave unidirectional frequency converter based on a parametrically pumped superconducting Josephson-junction transmission line, demonstrating better than 4.8 dB of inferred signal isolation from 6.6 to 11.4 GHz, with a maximum of 12 dB at 9.5 GHz. By using frequency diplexing techniques a conventional isolator could be implemented over this bandwidth.

Original languageAmerican English
Article number054035
JournalPhysical Review Applied
Issue number5
StatePublished - 17 Nov 2017
Externally publishedYes

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Publisher Copyright:
© 2017 American Physical Society.


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