Coupler-Assisted Leakage Reduction for Scalable Quantum Error Correction with Superconducting Qubits

• URL: http://arxiv.org/abs/2403.16155v2
• Date: Tue, 29 Oct 2024 08:53:14 GMT
• Title: Coupler-Assisted Leakage Reduction for Scalable Quantum Error Correction with Superconducting Qubits
• Authors: Xiaohan Yang, Ji Chu, Zechen Guo, Wenhui Huang, Yongqi Liang, Jiawei Liu, Jiawei Qiu, Xuandong Sun, Ziyu Tao, Jiawei Zhang, Jiajian Zhang, Libo Zhang, Yuxuan Zhou, Weijie Guo, Ling Hu, Ji Jiang, Yang Liu, Xiayu Linpeng, Tingyong Chen, Yuanzhen Chen, Jingjing Niu, Song Liu, Youpeng Zhong, Dapeng Yu,
• Abstract summary: leakage into non-computational states is a common issue in quantum systems including superconducting circuits. We propose and demonstrate a leakage reduction scheme utilizing tunable couplers, a widely adopted ingredient in large-scale superconducting quantum processors. We further reduce leakage to higher qubit levels with high efficiency (98.1%) and low error rate on the computational subspace (0.58%), suppressing time-correlated errors during QEC cycles.
• Score: 18.641408987868154
• License:
• Abstract: Superconducting qubits are a promising platform for building fault-tolerant quantum computers, with recent achievement showing the suppression of logical error with increasing code size. However, leakage into non-computational states, a common issue in practical quantum systems including superconducting circuits, introduces correlated errors that undermine QEC scalability. Here, we propose and demonstrate a leakage reduction scheme utilizing tunable couplers, a widely adopted ingredient in large-scale superconducting quantum processors. Leveraging the strong frequency tunability of the couplers and stray interaction between the couplers and readout resonators, we eliminate state leakage on the couplers, thus suppressing space-correlated errors caused by population propagation among the couplers. Assisted by the couplers, we further reduce leakage to higher qubit levels with high efficiency (98.1%) and low error rate on the computational subspace (0.58%), suppressing time-correlated errors during QEC cycles. The performance of our scheme demonstrates its potential as an indispensable building block for scalable QEC with superconducting qubits.

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