美国谷歌研究公司Habegger, S.课题组探明了（2 + 1）D晶格规范理论中电荷和弦的可视化动力学。2025年6月4日出版的《自然》杂志发表了这项成果。

晶格规范理论（LGT）可用于理解广泛的现象，从高能物理学中的基本粒子散射到材料中多体相互作用的有效描述。研究涌现相的动力学性质可能具有挑战性，因为它需要解决许多通常超出微扰极限的物体问题。 

研究组使用超导量子比特的二维晶格研究了(2+1)D LGT中局部激发的动力学。首先构建一个简单的变分电路，该电路准备与基态有较大重叠的低能态；然后用局域门创建电荷激发，并通过离散时间演化模拟它们的量子动力学。随着电场耦合常数的增加，该测量显示了从解精细动力学到受限动力学的转变特征。对于受限激励，电场在连接它们的弦中感应出张力。

该方法使研究组能够实验性地成像（2+1）D LGT中的弦动力学，从中发现了约束相中的两种不同状态：对于弱约束，弦在横向方向上强烈波动，而对于强约束，横向波动实际上是冻结的。研究组还证明了一个共振条件，在这个条件下，动力弦断裂变得容易。他们在量子处理器上实现的LGT为研究新兴激发和弦动力学提供了一套新技术。

附：英文原文

Title: Visualizing dynamics of charges and strings in (2 + 1)D lattice gauge theories

Author: Cochran, T. A., Jobst, B., Rosenberg, E., Lensky, Y. D., Gyawali, G., Eassa, N., Will, M., Szasz, A., Abanin, D., Acharya, R., Aghababaie Beni, L., Andersen, T. I., Ansmann, M., Arute, F., Arya, K., Asfaw, A., Atalaya, J., Babbush, R., Ballard, B., Bardin, J. C., Bengtsson, A., Bilmes, A., Bourassa, A., Bovaird, J., Broughton, M., Browne, D. A., Buchea, B., Buckley, B. B., Burger, T., Burkett, B., Bushnell, N., Cabrera, A., Campero, J., Chang, H.-S., Chen, Z., Chiaro, B., Claes, J., Cleland, A. Y., Cogan, J., Collins, R., Conner, P., Courtney, W., Crook, A. L., Curtin, B., Das, S., Demura, S., De Lorenzo, L., Di Paolo, A., Donohoe, P., Drozdov, I., Dunsworth, A., Eickbusch, A., Elbag, A. Moshe, Elzouka, M., Erickson, C., Ferreira, V. S., Burgos, L. Flores, Forati, E., Fowler, A. G., Foxen, B., Ganjam, S., Gasca, R., Genois, ., Giang, W., Gilboa, D., Gosula, R., Grajales Dau, A., Graumann, D., Greene, A., Gross, J. A., Habegger, S.

Issue&Volume: 2025-06-04

Abstract: Lattice gauge theories (LGTs)1,2,3,4 can be used to understand a wide range of phenomena, from elementary particle scattering in high-energy physics to effective descriptions of many-body interactions in materials5,6,7. Studying dynamical properties of emergent phases can be challenging, as it requires solving many-body problems that are generally beyond perturbative limits8,9,10. Here we investigate the dynamics of local excitations in a Z2 LGT using a two-dimensional lattice of superconducting qubits. We first construct a simple variational circuit that prepares low-energy states that have a large overlap with the ground state; then we create charge excitations with local gates and simulate their quantum dynamics by means of a discretized time evolution. As the electric field coupling constant is increased, our measurements show signatures of transitioning from deconfined to confined dynamics. For confined excitations, the electric field induces a tension in the string connecting them. Our method allows us to experimentally image string dynamics in a (2+1)D LGT, from which we uncover two distinct regimes inside the confining phase: for weak confinement, the string fluctuates strongly in the transverse direction, whereas for strong confinement, transverse fluctuations are effectively frozen11,12. We also demonstrate a resonance condition at which dynamical string breaking is facilitated. Our LGT implementation on a quantum processor presents a new set of techniques for investigating emergent excitations and string dynamics.

DOI: 10.1038/s41586-025-08999-9

Source: https://www.nature.com/articles/s41586-025-08999-9