Coherent optical control of spin-spin interaction in doped semiconductors

TL;DR

This paper develops a theoretical model for laser-controlled spin-spin interactions in doped semiconductors, enabling tunable magnetic coupling for quantum information applications.

Contribution

It provides an exact analytical solution for laser-induced spin interactions mediated by excitons, applicable to various impurity types in semiconductors.

Findings

Spin-spin interaction strength varies with laser energy and impurity type.

Interaction can switch from ferromagnetic to anti-ferromagnetic near exciton resonances.

The mechanism enables optical control of magnetic properties in semiconductor spin systems.

Abstract

We provide a theory of laser-induced interaction between spins localized by impurity centers in a semiconductor host. By solving exactly the problem of two localized spins interacting with one itinerant exciton, an analytical expression for the induced spin-spin interaction is given as a function of the spin separation, laser energy, and intensity. We apply the theory to shallow neutral donors (Si) and deep rare-earth magnetic impurities (Yb) in III-V semiconductors. When the photon energy approaches a resonance related to excitons bound to the impurities, the coupling between the localized spins increases, and may change from ferromagnetic to anti-ferromagnetic. This light-controlled spin interaction provides a mechanism for the quantum control of spins in semiconductors for quantum information processing; it suggests the realization of spin systems whose magnetic properties can be controlled by changing the strength and the sign of the spin-spin interaction.