Mechanically induced correlated errors on superconducting qubits with relaxation times exceeding 0.4 ms

• Published in: Nature communications Vol. 15; no. 1; pp. 3950 - 12
• Main Authors: Kono, Shingo, Pan, Jiahe, Chegnizadeh, Mahdi, Wang, Xuxin, Youssefi, Amir, Scigliuzzo, Marco, Kippenberg, Tobias J.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 10.05.2024; Nature Publishing Group; Nature Portfolio
• Subjects: 639/766/483/2802; 639/766/483/481; Correlation; Decoupling; Dilution; Error correction; Fault tolerance; Humanities and Social Sciences; multidisciplinary; Pulse tubes; Quantum computing; Qubits (quantum computing); Science; Science (multidisciplinary); Superconductivity; Time measurement; Time synchronization; Vibrations
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-024-48230-3

Superconducting qubits are among the most advanced candidates for achieving fault-tolerant quantum computing. Despite recent significant advancements in the qubit lifetimes, the origin of the loss mechanism for state-of-the-art qubits is still subject to investigation. Furthermore, the successful implementation of quantum error correction requires negligible correlated errors between qubits. Here, we realize long-lived superconducting transmon qubits that exhibit fluctuating lifetimes, averaging 0.2 ms and exceeding 0.4 ms – corresponding to quality factors above 5 million and 10 million, respectively. We then investigate their dominant error mechanism. By introducing novel time-resolved error measurements that are synchronized with the operation of the pulse tube cooler in a dilution refrigerator, we find that mechanical vibrations from the pulse tube induce nonequilibrium dynamics in highly coherent qubits, leading to their correlated bit-flip errors. Our findings not only deepen our understanding of the qubit error mechanisms but also provide valuable insights into potential error-mitigation strategies for achieving fault tolerance by decoupling superconducting qubits from their mechanical environments. Significant efforts have been dedicated to understanding the mechanisms of decoherence in superconducting qubits. Here, using time-resolved error measurements, the authors link errors present in transmon qubits based on Nb electrodes to mechanical vibrations of a commonly used pulse tube cooler.