Spin decomposition and topological properties in a generic electromagnetic field
Abstract
Electromagnetic spins, including longitudinal and transverse ones, have been playing important roles in light-matter interactions. Here, we formulate a unified equation to uncover the physical origins and topological properties of longitudinal and transverse spins in a generic electromagnetic field. The equation reveals universally that the transverse spin is locked with the kinetic momentum and originated from the transverse inhomogeneities of field, whereas the helix-dependent longitudinal spin orients parallel to the local wavevector. Remarkably, a hidden extraordinary helix-dependent transverse spin possessing helix-dependent spin-momentum locking is discovered and the number of locking states consistent with the nontrivial topological spin Chern number. Furthermore, this spin which determines the inverted helical components is related to the Berry curvature closely. The findings, which are demonstrated experimentally by measuring the three-dimensional spin components in the focusing configuration, will deepen the understanding the underlying physics of spins and open an avenue for chiral quantum optical applications.
Cite
@article{arxiv.2108.00725,
title = {Spin decomposition and topological properties in a generic electromagnetic field},
author = {Peng Shi and Aiping Yang and Xiaojin Yin and Luping Du and Xinrui Lei and Xiaocong Yuan},
journal= {arXiv preprint arXiv:2108.00725},
year = {2022}
}
Comments
15 pages, 3 figures, 2 table, 7 equations, 56 references in main text; 39 pages, 16 figures, 100 equations, 16 references in supplemental materials