Building large-scale superconducting quantum circuits will require miniaturisation and integration of supporting devices including microwave circulators, which are currently bulky, stand-alone components. Here we report the realisation of a passive on-chip circulator which is made from a loop consisting of three tunnel-coupled superconducting islands, with DC-only control fields. We observe the effect of quasiparticle tunnelling, and we dynamically classify the system into different quasiparticle sectors. When tuned for circulation, the device exhibits strongly non-reciprocal 3-port scattering, with average on-resonance insertion loss of 2 dB, isolation of 14 dB, power reflectance of -11 dB, and a bandwidth of 200 MHz.
@article{arxiv.2308.14643,
title = {Passive microwave circulation on a superconducting chip},
author = {Arkady Fedorov and N. Pradeep Kumar and Dat Thanh Le and Rohit Navarathna and Prasanna Pakkiam and Thomas M. Stace},
journal= {arXiv preprint arXiv:2308.14643},
year = {2023}
}