Signatures of Spin Coherence in Chiral Coupled Quantum Dots

TL;DR

This paper demonstrates that chiral quantum dot assemblies exhibit spin-dependent photoluminescence dynamics influenced by magnetic fields, revealing quantum coherence effects related to the chiral-induced spin selectivity (CISS) phenomenon at room temperature.

Contribution

It provides the first experimental evidence of quantum coherent spin precession in chiral quantum dot assemblies, linking CISS to observable spin dynamics.

Findings

PL lifetime varies with magnetic field magnitude and orientation.

Spin precession depends on the transverse magnetic field component.

Model reproduces experimental spin dynamics trends.

Abstract

Chiral-induced spin selectivity (CISS) enables spin selectivity of charge carriers in chiral molecular systems without magnetic materials. While spin selectivity has been widely investigated, its quantum coherence has not yet been explored. Here, we investigate spin-dependent photoluminescence (PL) dynamics in multilayer quantum-dot (QD) assemblies coupled by chiral linkers. Using circularly polarized excitation in the presence of an external magnetic field, we observe a pronounced modulation of the PL lifetime that depends on the magnetic field magnitude and geometry. The lifetime difference between left- and right-circularly polarized excitations exhibits a field-angle dependence, consistent with spin precession driven by the transverse magnetic-field component relative to the chiral axis. A model incorporating coupled spin precession and decay processes reproduces the experimental trends. These results establish chiral QD assemblies as a room-temperature platform for probing quantum coherent manifestations of the CISS effect, with implications for spintronic and quantum technologies.