Observation of emergent <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi mathvariant="double-struck">Z</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math> gauge invariance in a superconducting circuit
Zhan Wang, Zi-Yong Ge, Zhongcheng Xiang, Xiaohui Song, Rui-Zhen Huang, Pengtao Song, Xueyi Guo, Luhong Su, Kai Xu, Dongning Zheng, Heng Fan
Abstract
Lattice gauge theories (LGTs) are one of the most fundamental subjects in many-body physics, and has recently attracted considerable research interests in quantum simulations. Here we experimentally investigate the emergent Z 2 gauge invariance in a 1D superconducting circuit with 10 transmon qubits. By precisely adjusting staggered longitudinal and transverse fields to each qubit, we construct an effective Hamiltonian containing an LGT and gauge-broken terms. The corresponding matter sector can exhibit a localization, and there also exists a 3-qubit operator, of which the expectation value can retain nonzero for a long time in low-energy regimes. The above localization can be regarded as the confinement of matter fields, and the 3-body operator is the Z 2 gauge generator. These experimental results demonstrate that, despite the absence of gauge structure in the effective Hamiltonian, Z 2 gauge invariance can still emerge in low-energy regimes. Our work provides a method for both theoretically and experimentally studying the rich physics in quantum many-body systems with emergent gauge invariance.