Real-Time Correlation of Relaxation, Dephasing, and Two-level System Dynamics in Transmon Qubits
Abstract
Materials improvements in transmon qubits have yielded remarkable advances in qubit lifetimes (T1)and coherence times (T2). However, state-of-the-art superconducting qubits experience temporal fluctuations in their performance, which limit gate fidelities and quantum processor performance. We observe correlated increases in qubit relaxation and dephasing rates that last for minutes to hours, which we call T1 and T2 excursions. Using interleaved lifetime and coherence time measurements, noise spectroscopy, and two-level-system (TLS) spectroscopy, we find that these excursions are caused by single or few strongly-coupled TLS defects that spectrally diffuse into resonance with the qubit frequency. Our measurement protocol provides a powerful tool for understanding the noise sources that cause temporal fluctuations in superconducting qubit performance.
Related
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BibTeX
@misc{yang2026realtime,
title = {{Real-Time Correlation of Relaxation, Dephasing, and Two-level System Dynamics in Transmon Qubits}},
author = {Ambrose Yang and Alexander M. Young and Paal H. Prestegaard and Atharv Joshi and Matthew S. Ai and Q. Rumman Rahman and Faranak Bahrami and Matthew P. Bland and Jui-Lin Niu and Ourania-Maria Glezakou-Elbert and Ray D. Chang and Jocelyn Liu and Zhengyi Lu and Robert J. Cava and Nathalie P. de Leon and Andrew A. Houck},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.34485},
eprint = {2610.34485},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.34485},
}
RIS
TY - UNPB
TI - Real-Time Correlation of Relaxation, Dephasing, and Two-level System Dynamics in Transmon Qubits
AU - Ambrose Yang
AU - Alexander M. Young
AU - Paal H. Prestegaard
AU - Atharv Joshi
AU - Matthew S. Ai
AU - Q. Rumman Rahman
AU - Faranak Bahrami
AU - Matthew P. Bland
AU - Jui-Lin Niu
AU - Ourania-Maria Glezakou-Elbert
AU - Ray D. Chang
AU - Jocelyn Liu
AU - Zhengyi Lu
AU - Robert J. Cava
AU - Nathalie P. de Leon
AU - Andrew A. Houck
PY - 2026
DA - 2026/10/25
PB - arXiv
DO - 10.48550/arxiv.2610.34485
UR - https://arxiv.org/abs/2610.34485
AB - Materials improvements in transmon qubits have yielded remarkable advances in qubit lifetimes (T1)and coherence times (T2). However, state-of-the-art superconducting qubits experience temporal fluctuations in their performance, which limit gate fidelities and quantum processor performance. We observe correlated increases in qubit relaxation and dephasing rates that last for minutes to hours, which we call T1 and T2 excursions. Using interleaved lifetime and coherence time measurements, noise spectroscopy, and two-level-system (TLS) spectroscopy, we find that these excursions are caused by single or few strongly-coupled TLS defects that spectrally diffuse into resonance with the qubit frequency. Our measurement protocol provides a powerful tool for understanding the noise sources that cause temporal fluctuations in superconducting qubit performance.
ER -