Readout failures in superconducting qubits due to TLS-defects in tunnel junctions

• URL: http://arxiv.org/abs/2605.02755v1
• Date: Mon, 04 May 2026 15:56:40 GMT
• Title: Readout failures in superconducting qubits due to TLS-defects in tunnel junctions
• Abstract summary: We study a strongly coupled TLS that resides in the tunnel barrier of transmon qubit.<n>This reveals a strong effective resonant coupling between the TLS and the qubit's readout resonator.
• Score: 0.0
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: Material defects give rise to parasitic two-level systems (TLS) which present a major source of decoherence in superconducting qubits. Here, we study a strongly coupled TLS that resides in the tunnel barrier of transmon qubit. We use multi-photon spectroscopy and TLS strain tuning to explore the rich spectrum of the interacting three-partite system consisting of TLS, qubit, and its readout resonator. This reveals a strong effective resonant coupling between the TLS and the qubit's readout resonator which dresses the resonator states and results in a resonance frequency shift that spoils the readout signal. Our finding presents yet another way how material defects can interfere with qubit operation and hinder the realization of solid-state quantum processors.

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