A passive, on-chip microwave circulator using a ring of tunnel junctions
Clemens Müller1,2, Shengwei Guan2, Nicolas Vogt3, Jared H. Cole3, Thomas M. Stace2
1Institute for Theoretical Physics, ETH Zurich, Zurich, Switzerland
2ARC Centre of Excellence for Engineered Quantum Systems, The University of Queensland, Brisbane, Australia
3Chemical and Quantum Physics, RMIT University, Melbourne, Australia
The unavailability of integrated microwave circulators is currently one of the major roadblocks on the way towards true scaling up of superconductor based quantum technology, with many recent proposals aimed at overcoming this capability gap. In general, these require additional microwave or radiofrequency components and therefore increase control complexity signi cantly. Here, I will present our recent proposal for a fully passive, on-chip microwave circulator based on a ring of superconducting tunnel junctions [1]. We investigate two distinct physical realisations, based on either Josephson junctions (JJ) or quantum phase slip elements (QPS), with microwave ports coupled either capacitively (JJ) or inductively (QPS) to the ring structure. A constant bias applied to the center of the ring provides the symmetry breaking (e ective) magnetic eld, and no microwave or rf bias is required. We nd that this design o ers high isolation even when taking into
account fabrication imperfections and environmentally induced bias perturbations and nd a bandwidth in excess of 500 MHz for realistic device parameters.
[1] CM, S. Guan, N. Vogt, J. H. Cole, and Thomas M. Stace, arXiv:1709:09826 (2017)