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arXiv · 2107.13175

Ultrastrong tunable coupler between superconducting LC resonators

Takafumi Miyanaga·Akiyoshi Tomonaga·Hikaru Ito·Hiroto Mukai·Jaw-Shen Tsai
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Abstract

We investigate the ultrastrong tunable coupler for coupling of superconducting resonators. Obtained coupling constant exceeds 1 GHz, and the wide range tunability is achieved both antiferromagnetics and ferromagnetics from $-1086$ MHz to 604 MHz. The ultrastrong coupler is composed of rf-SQUID and dc-SQUID as tunable junctions, which connected to resonators via shared aluminum thin film meander lines enabling such a huge coupling constant. The spectrum of the coupler obviously shows the breaking of the rotating wave approximation, and our circuit model treating the Josephson junction as a tunable inductance reproduces the experimental results well. The ultrastrong coupler is expected to be utilized in quantum annealing circuits and/or NISQ devices with dense connections between qubits.

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Takafumi Miyanaga, Akiyoshi Tomonaga, Hikaru Ito, Hiroto Mukai, Jaw-Shen Tsai. 2021-07-28. Ultrastrong tunable coupler between superconducting LC resonators. https://doi.org/10.1103/physrevapplied.16.064041

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