Pseudo-Hermitian Framework and Ultrafast Evidence for Chirality-Induced Spin–Charge Conversion at Solid Interfaces

Chirality-induced spin selectivity (CISS) couples electron spin and momentum in structural chiral systems, producing spin polarization even under nominal equilibrium conditions. Such observations challenge conventional expectations from Hermitian quantum mechanics and Onsager reciprocity. Using terahertz emission spectroscopy, we directly probe the inverse CISS process. The picosecond response reveals a spin–induced charge current at solid interfaces. To interpret these results, we develop a pseudo-Hermitian formulation of spin-charge quantum transport. This framework admits real spectra and consistent thermodynamic behavior while allowing reversible spin–charge interconversion. The combined results clarify equilibrium signatures of CISS and provide guiding principles for modeling and exploiting nonreciprocal spin transport at chiral interfaces.