High-frequency suppression of inductive coupling between flux qubit and transmission line resonator

• URL: http://arxiv.org/abs/2308.07849v3
• Date: Sat, 2 Mar 2024 10:02:42 GMT
• Title: High-frequency suppression of inductive coupling between flux qubit and transmission line resonator
• Authors: Sahel Ashhab, Ziqiao Ao, Fumiki Yoshihara, Adrian Lupascu, Kouichi Semba
• Abstract summary: We investigate the naturally occurring high-frequency cutoff in a circuit comprising a flux qubit coupled inductively to a transmission line resonator (TLR) We derive expressions for the mode frequencies, qubit-TLR coupling strengths and qubit Lamb shift. We identify features in the spectrum of the system that can be used in future experiments to test and validate the theoretical model.
• Score: 2.0249250133493195
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: We perform theoretical calculations to investigate the naturally occurring high-frequency cutoff in a circuit comprising a flux qubit coupled inductively to a transmission line resonator (TLR). Specifically, a decoupling occurs between the qubit and the high-frequency modes. The coupling strength between the qubit and resonator modes increases with mode frequency $\omega$ as $\sqrt{\omega}$ at low frequencies and decreases as $1/\sqrt{\omega}$ at high frequencies. This result is similar to those of past studies that considered somewhat similar circuit designs. By avoiding the approximation of ignoring the qubit-TLR coupling in certain steps in the analysis, we obtain effects not captured in previous studies. In particular, we obtain a resonance effect that shifts the TLR mode frequencies close to qubit oscillation frequencies. We derive expressions for the TLR mode frequencies, qubit-TLR coupling strengths and qubit Lamb shift. We identify features in the spectrum of the system that can be used in future experiments to test and validate the theoretical model.

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