Emerging Electrodynamics and Topological Instanton in Pseudo-Hermitian Two-Level Systems
Phys. Rev. Lett. 135, 126609 – Published 18 September, 2025
DOI: https://doi.org/10.1103/kcls-cn82
Abstract
We reveal a hidden electrodynamical structure emerging from a general pseudo-Hermitian system that exhibits real spectra. Even when the Hamiltonian does not explicitly depend on time, the Berry curvature can be mapped onto a -dimensional electromagnetic field arising from an artificial spacetime instanton, in sharp contrast to the Hermitian systems where the Berry curvature is equivalent to the static magnetic field of a magnetic monopole in three spatial dimensions. The instanton appearing as a spacetime singularity carries a topological charge that quantizes the jump of magnetic flux of the Berry curvature at the time origin. Our findings are demonstrated in a simple example related to antiferromagnetic magnons.