德国量子研究所Khaldoon Ghanem团队实现了紧凑费米子编码的收支平衡实验证明。2025年6月16日出版的《自然—物理学》杂志发表了这项成果。

求解费米-哈伯德模型是研究强相关材料的核心任务。原则上，数字量子计算机可以适用于这一目的，但迄今为止仅限于准一维模型。这是因为噪声的相互作用以及费米子和量子位之间映射的非局域性造成的指数开销。 

研究组使用捕获离子量子计算机来实验证明，最近开发的局部编码可以克服这个问题。特别是，他们表明，对项进行适当的重新排序和电路恒等式的应用——一种称为角跳的方案——大大降低了模拟费米子跳变的成本。这使得能够有效地制备编码在48个物理量子位中的6 × 6无自旋费米-哈伯德模型的基态。研究组还分别基于局部后选择和局部可观测值的外推，为具有守恒量的系统开发了两种误差缓解方案。我们的研究结果表明，数字量子计算机可以解决经典可模拟性之外的费米-哈伯德模型，而无需大幅提高门保真度。

附：英文原文

Title: Experimental demonstration of breakeven for a compact fermionic encoding

Author: Nigmatullin, Ramil, Hmery, Kvin, Ghanem, Khaldoon, Moses, Steven, Gresh, Dan, Siegfried, Peter, Mills, Michael, Gatterman, Thomas, Hewitt, Nathan, Granet, Etienne, Dreyer, Henrik

Issue&Volume: 2025-06-16

Abstract: Solving the Fermi–Hubbard model is a central task in the study of strongly correlated materials. Digital quantum computers can, in principle, be suitable for this purpose, but have so far been limited to quasi-one-dimensional models. This is because of exponential overheads caused by the interplay of noise and the non-locality of the mapping between fermions and qubits. Here we use a trapped-ion quantum computer to experimentally demonstrate that a recently developed local encoding can overcome this problem. In particular, we show that suitable reordering of terms and application of circuit identities—a scheme called corner hopping—substantially reduces the cost of simulating fermionic hopping. This enables the efficient preparation of the ground state of a 6×6 spinless Fermi–Hubbard model encoded in 48 physical qubits. We also develop two error mitigation schemes for systems with conserved quantities, based on local postselection and on extrapolation of local observables, respectively. Our results suggest that Fermi–Hubbard models beyond classical simulability can be addressed by digital quantum computers without large increases in gate fidelity.

DOI: 10.1038/s41567-025-02931-8

Source: https://www.nature.com/articles/s41567-025-02931-8