Work

Readout failures in superconducting qubits due to two-level system defects in tunnel junctions

Year: 2026

Type: article

Abstract: Material defects give rise to parasitic two-level systems (TLS) that 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 multiphoton 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.

Source: Physical Review Research

DOI: 10.1103/ypm5-lh8d

Authors: Jürgen Lisenfeld, Alexander K. Händel, Alexander Bilmes, Alexey V. Ustinov

Institution: Karlsruhe Institute of Technology

Language: English

Topic: Quantum Information and Cryptography

Subfield: Artificial Intelligence

Field: Computer Science

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $2,625

Funders: Karlsruhe Institute of Technology, Deutsche Forschungsgemeinschaft, Bundesministerium für Bildung und Forschung, Ministerium für Wissenschaft, Forschung und Kunst Baden-Württemberg