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Updated: Jun 12, 2026

Fabrication and Characterization of Superconducting Resonators
Published on: May 21, 2016
rf-SQUID-mediated coherent tunable coupling between a superconducting phase qubit and a lumped-element resonator
M S Allman1, F Altomare, J D Whittaker
1National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305-3328, USA.
Abstract:
We demonstrate coherent tunable coupling between a superconducting phase qubit and a lumped-element resonator. The coupling strength is mediated by a flux-biased rf SQUID operated in the nonhysteretic regime. By tuning the applied flux bias to the rf SQUID we change the effective mutual inductance, and thus the coupling energy, between the phase qubit and resonator. We verify the modulation of coupling strength from 0 to 100 MHz by observing modulation in the size of the splitting in the phase qubit's spectroscopy, as well as coherently by observing modulation in the vacuum Rabi oscillation frequency when on resonance. The measured spectroscopic splittings and vacuum Rabi oscillations agree well with theoretical predictions.
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