Characterization of multi-level dynamics and decoherence in a high-anharmonicity capacitively shunted flux circuit

• URL: http://arxiv.org/abs/2008.00593v2
• Date: Thu, 24 Feb 2022 19:58:17 GMT
• Title: Characterization of multi-level dynamics and decoherence in a high-anharmonicity capacitively shunted flux circuit
• Authors: M.A. Yurtalan, J. Shi, G.J.K. Flatt, A. Lupascu
• Abstract summary: We present a three-Josephson-junction superconducting circuit with three large capacitors as a qubit. The circuit shows long energy-relaxation times, order of the qubit, and a spin-echo dephaing time. These results demonstrate potential use for fastsecond-time-scale nano-scale quantum logic.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: We present the design and characterization of a three-Josephson-junction superconducting loop circuit with three large shunt capacitors. Used as a qubit, the circuit shows long energy-relaxation times, of the order of 40 ${ \unicode[Times]{x3BC}}$s and a spin-echo dephasing time of 9.4 ${ \unicode[Times]{x3BC}}$s. The circuit has high anharmonicity, of 2$\pi$$\times$3.69 GHz. We extract the multilevel relaxation and dephasing rates of the circuit used as a qutrit and discuss the possible sources for the decoherence. The high anharmonicity allows for fast qubit control with nanosecond-range gate durations and a measured average gate fidelity of 99.92%, characterized by randomized benchmarking. These results demonstrate interesting potential use for fast nanosecond-time-scale two-qubit gates and multilevel quantum logic.

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