Tunable Superconductivity

克信 青柳, Yoshinobu Aoyagi

克信 青柳, Yoshinobu Aoyagi

James F. Annett, S. P. Kruchinin

Mingchao Li, Kuangyong Gao, Xingkun You +6 more

A superconducting tunable filter with fixed inputoutput position was proposed in this letter. The superconducting tunable filter mainly consists of a folded open ring and two tunable capacitors loaded at the open end of the ring. In order to maintain the input/output ports in a fixed position, the input/output resonant cavity adopts a zigzag resonant structure to achieve the adjustment of superconducting input/output position in different frequency bands and ensure the fixed position. A superconducting tunable filter composing of six tunable resonators has been designed, fabricated and measured. The measured results demonstrate the effectiveness of the method described in this article.

道生 渡部, Koji Ishibashi, Yoshinobu Aoyagi

Samuel Kim, David B. Shrekenhamer, K. McElroy +2 more

Abstract Here we consider a tunable superconducting cavity that can be used either as a tunable coupler to a qubit inside the cavity or as a tunable low noise, low temperature, RF filter. Our design consists of an array of radio-frequency superconducting quantum interference devices (rf SQUIDs) inside a superconducting cavity. This forms a tunable metamaterial structure which couples to the cavity through its magnetic plasma frequency. By tuning the resonant frequency of the metamaterial through an applied magnetic flux, one can tune the cavity mode profile. This allows us to detune the cavity initially centered at 5.593 GHz by over 200 MHz. The maximum quality factor approaches that of the empty cavity, which is 4.5 × 106. The metamaterial electromagnetic response is controlled via a low-frequency or dc magnetic flux bias, and we present a control line architecture that is capable of applying sufficient magnetic flux bias with minimal parasitic coupling. Together this design allows for an in-situ tunable cavity which enables low-temperature quantum control applications.