Hu Chang-Kang, Wang Yong, Zhou YuXuan, Liu ChiLong, Xie GuiXu, Zhou RuiYang, Yuan HaoLan, Liu Lijun, Li Li, Liu Song, Tan Dian, Cheng Shuming, Yu Dapeng
Southern University of Science and Technology, Shenzhen Institute for Quantum Science and Engineering, Shenzhen, Guangdong 518055, China.
International Quantum Academy, Futian District, Shenzhen, Guangdong 518048, China.
Phys Rev Lett. 2025 Aug 15;135(7):070801. doi: 10.1103/qy9y-7ywp.
We present a least square state estimator regularized by state purity to accomplish the task of quantum state tomography and entanglement verification, and report an experimental validation on a superconducting processor. First, a scalable full-state tomography is achieved with state fidelity 0.8217(1) for the 9-qubit W state and 0.6817(1) for the 17-qubit Greenberger-Horne-Zeilinger state, with the latter reaching 0.7587(1) under a pure-state assumption. Then, the presence of genuine multiqubit entanglement in the majority of generated states is conclusively certified by violating the corresponding entanglement witness. Finally, it is demonstrated that our method can achieve superior tomography accuracy with limited measurement settings and that mitigating error is essential for leveraging noisy quantum systems in quantum processing tasks. Our results pave the way for more accurate full characterization of larger-scale many-body quantum systems.
我们提出一种通过态纯度正则化的最小二乘状态估计器，以完成量子态层析成像和纠缠验证任务，并报告在超导处理器上的实验验证。首先，对于9比特W态，实现了具有0.8217(1)的态保真度的可扩展全态层析成像；对于17比特格林伯格-霍恩-泽林格态，实现了0.6817(1)的态保真度，在纯态假设下，后者达到0.7587(1)。然后，通过违反相应的纠缠见证，确凿地证明了在大多数生成态中存在真正的多比特纠缠。最后，证明了我们的方法可以在有限的测量设置下实现更高的层析成像精度，并且减轻误差对于在量子处理任务中利用噪声量子系统至关重要。我们的结果为更准确地表征更大规模的多体量子系统铺平了道路。
