一句话：提出 QuFEM，用分治张量积与稀疏引擎实现快速准确的量子读出校准。
量子读出噪声是影响测量保真度的主要误差源，矩阵校准虽有效但难以兼顾可扩展性与精度。受有限元方法建模元素间复杂相互作用的启发，QuFEM 将校准表述为一系列带噪声矩阵的张量积，采用分治策略迭代刻画噪声矩阵与校准概率分布，以利用量子比特相互作用的局部性；并设计稀疏张量积引擎加速端到端校准。实验表明，在 136 比特校准中，QuFEM 相比先进矩阵校准方法取得 2.5×10^3× 加速，并在 18 比特和 36 比特真实量子设备上分别带来 1.2× 和 1.4× 的保真度提升。
Quantum readout noise turns out to be the most significant source of error, which greatly affects the measurement fidelity. Matrix-based calibration has been demonstrated to be effective in various quantum platforms. However, existing methodologies are fundamentally limited in either scalability or accuracy. Inspired by the classical finite element method (FEM), a formal method to model the complex interaction between elements, we present our calibration framework named QuFEM. First, we apply a divide-and-conquer strategy that formulates the calibration as a series of tensor products with noise matrices. This matrices are iteratively characterized together with the calibrated probability distribution, aiming to capture the inherent locality of qubit interactions. Then, to accelerate the end-to-end calibration, we propose a sparse tensor-product engine to exploit the sparsity in the intermediate values. Our experiments show that QuFEM achieves 2.5×103× speedup in the 136-qubit calibration compared to the state-of-the-art matrix-based calibration technique [50], and provides 1.2× and 1.4× fidelity improvement on the 18-qubit and 36-qubit real-world quantum devices.
@inproceedings{TanLZYLSZC0Y24,
title = {QuFEM: Fast and Accurate Quantum Readout Calibration Using the Finite Element Method},
author = {Siwei Tan and Liqiang Lu and Hanyu Zhang and Jia Yu and Congliang Lang and Yongheng Shang and Xinkui Zhao and Mingshuai Chen and Yun Liang and Jianwei Yin},
booktitle = {ASPLOS},
year = {2024},
doi = {10.1145/3620665.3640380}
}