Tohoku Univ. Technology：Self-shunted flux-type superconducting quantum circuit element: T22-242

Realization of high performance, highly integrated quantum computer by increased coherence time, anharmonicity, and reduced footprint of qubit

　The superconducting quantum bit is composed of a single or multiple superconducting tunnel junctions (Josephson junctions). Research and development of typical charge type and magnetic flux type qubits are active. The current mainstream of high integration is Transmon, a modified version of the charge type, which has advantage of long coherence time, but has disadvantage of small anharmonicity, which can cause error. On the other hand, the magnetic flux type has advantage of large anharmonicity, but has disadvantage of short coherence time. Adding a shunt capacitor to increase coherence time causes increased footprint (the area occupied by a single qubit).　 　This invention solves above problem, and it is about a technology that can achieve high integration with a small footprint while maintaining a practically tolerable coherence time and anharmonicity.

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