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Single-photon exchange interaction in a semiconductor microcavity

G. Chiappe·J. Fernández-Rossier·E. Louis·E. Anda
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Abstract

We consider the effective coupling of localized spins in a semiconductor quantum dot embedded in a microcavity. The lowest cavity mode and the quantum dot exciton are coupled and close in energy, forming a polariton. The fermions forming the exciton interact with localized spins via exchange. Exact diagonalization of a Hamiltonian in which photons, spins and excitons are treated quantum mechanically shows that {\it a single polariton} induces a sizable indirect exchange interaction between otherwise independent spins. The origin, symmetry properties and the intensity of that interaction depend both on the dot-cavity coupling and detuning. In the case of a (Cd,Mn)Te quantum dot, Mn-Mn ferromagnetic coupling mediated by a single photon survives above 1 K whereas the exciton mediated coupling survives at 15 K.

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G. Chiappe, J. Fernández-Rossier, E. Louis, E. Anda. 2004-07-23. Single-photon exchange interaction in a semiconductor microcavity. https://doi.org/10.1103/physrevb.72.245311

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