Low-loss on-chip superconducting microwave circulator assisted by shunting capacitors

Ferrite-free circulators that are passive and readily integratable on a chip are highly sought-after in quantum technologies based on superconducting circuits. In our previous work, we implemented such a circulator using a three-Josephson-junction loop that exhibited unambiguous nonreciprocity and s...

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Main Authors: N. Pradeep Kumar, Dat Thanh Le, Prasanna Pakkiam, Thomas M. Stace, Arkady Fedorov
Format: Article
Language:English
Published: American Physical Society 2025-01-01
Series:Physical Review Research
Online Access:http://doi.org/10.1103/PhysRevResearch.7.013075
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author N. Pradeep Kumar
Dat Thanh Le
Prasanna Pakkiam
Thomas M. Stace
Arkady Fedorov
author_facet N. Pradeep Kumar
Dat Thanh Le
Prasanna Pakkiam
Thomas M. Stace
Arkady Fedorov
author_sort N. Pradeep Kumar
collection DOAJ
description Ferrite-free circulators that are passive and readily integratable on a chip are highly sought-after in quantum technologies based on superconducting circuits. In our previous work, we implemented such a circulator using a three-Josephson-junction loop that exhibited unambiguous nonreciprocity and signal circulation, but required junction energies to be within 1% of design values. This tolerance is tighter than standard junction fabrication methods provide, so we propose and demonstrate a design improvement that relaxes the required junction fabrication precision, allowing for higher device performance and fabrication yield. Specifically, we introduce large direct capacitive couplings between the waveguides, which based on the modeling we describe here, requires less stringent junction fabrication tolerance. We implement the design, and measure enhanced “circulation fidelity” above 97%, with optimized on-resonance insertion loss of 0.2 dB, isolation of 18 dB, and power reflectance of −15dB, in good agreement with model calculations.
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institution Kabale University
issn 2643-1564
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publishDate 2025-01-01
publisher American Physical Society
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series Physical Review Research
spelling doaj-art-de2715cef95a457bb0b4a5c622c2ee352025-01-21T15:11:02ZengAmerican Physical SocietyPhysical Review Research2643-15642025-01-017101307510.1103/PhysRevResearch.7.013075Low-loss on-chip superconducting microwave circulator assisted by shunting capacitorsN. Pradeep KumarDat Thanh LePrasanna PakkiamThomas M. StaceArkady FedorovFerrite-free circulators that are passive and readily integratable on a chip are highly sought-after in quantum technologies based on superconducting circuits. In our previous work, we implemented such a circulator using a three-Josephson-junction loop that exhibited unambiguous nonreciprocity and signal circulation, but required junction energies to be within 1% of design values. This tolerance is tighter than standard junction fabrication methods provide, so we propose and demonstrate a design improvement that relaxes the required junction fabrication precision, allowing for higher device performance and fabrication yield. Specifically, we introduce large direct capacitive couplings between the waveguides, which based on the modeling we describe here, requires less stringent junction fabrication tolerance. We implement the design, and measure enhanced “circulation fidelity” above 97%, with optimized on-resonance insertion loss of 0.2 dB, isolation of 18 dB, and power reflectance of −15dB, in good agreement with model calculations.http://doi.org/10.1103/PhysRevResearch.7.013075
spellingShingle N. Pradeep Kumar
Dat Thanh Le
Prasanna Pakkiam
Thomas M. Stace
Arkady Fedorov
Low-loss on-chip superconducting microwave circulator assisted by shunting capacitors
Physical Review Research
title Low-loss on-chip superconducting microwave circulator assisted by shunting capacitors
title_full Low-loss on-chip superconducting microwave circulator assisted by shunting capacitors
title_fullStr Low-loss on-chip superconducting microwave circulator assisted by shunting capacitors
title_full_unstemmed Low-loss on-chip superconducting microwave circulator assisted by shunting capacitors
title_short Low-loss on-chip superconducting microwave circulator assisted by shunting capacitors
title_sort low loss on chip superconducting microwave circulator assisted by shunting capacitors
url http://doi.org/10.1103/PhysRevResearch.7.013075
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