Hengrui Yang | Searcharxiv

arXiv2026

The Counterintuitive "One-Enhanced, One-Suppressed" Bifurcation Phenomenon of Spin Mobility under Weak Spin-Orbit Coupling in Helices

The chiral-induced spin selectivity (CISS) effect poses a longstanding puzzle: how weak spin-orbit coupling (SOC) within a helical molecule produces strong spin polarization. We uncover a counterintuitive phenomenon, a "one-enhanced, one-suppressed" bifurcation of spin-resolved mobility relative to the SOC-free case. We trace this phenomenon to an analytical sign reversal of spin-dependent transmission and identify it as the microscopic origin of CISS. The phenomenon is found absent in achiral systems and single-stranded DNA, validating our theoretical picture. Our findings resolve the core puzzle and establish the origin of CISS.

cond-mat.other↗

arXiv2024

Optimal Tree Tensor Network Operators for Tensor Network Simulations: Applications to Open Quantum Systems

Tree tensor network states (TTNS) decompose the system wavefunction to the product of low-rank tensors based on the tree topology, serving as the foundation of the multi-layer multi-configuration time-dependent Hartree (ML-MCTDH) method. In this work, we present an algorithm that automatically constructs the optimal and exact tree tensor network operators (TTNO) for any sum-of-product symbolic quantum operator.The construction is based on the minimum vertex cover of a bipartite graph. With the optimal TTNO, we simulate open quantum systems such as spin relaxation dynamics in the spin-boson model and charge transport in molecular junctions. In these simulations, the environment is treated as discrete modes and its wavefunction is evolved on equal footing with the system. We employ the Cole-Davidson spectral density to model the glassy phonon environment, and incorporate temperature effects via thermo field dynamics. Our results show that the computational cost scales linearly with the number of discretized modes, demonstrating the efficiency of our approach.

quant-ph↗