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Nature Communications

Spin–cavity interactions between a quantum dot molecule and a photonic crystal cavity

Patrick M. Vora, Allan S. Bracker, Sam Carter, Timothy M. Sweeney, Mijin Kim, Chul Soo Kim, Lily Yang, Peter Brereton, Sophia E. Economou, D. Gammon

Published Jul 17, 2015• 58 citations

Abstract

The integration of InAs/GaAs quantum dots into nanophotonic cavities has led to impressive demonstrations of cavity quantum electrodynamics. However, these demonstrations are primarily based on two-level excitonic systems. Efforts to couple long-lived quantum dot electron spin states with a cavity are only now succeeding. Here we report a two-spin-cavity system, achieved by embedding an InAs quantum dot molecule within a photonic crystal cavity. With this system we obtain a spin singlet-triplet Λ-system where the ground-state spin splitting exceeds the cavity linewidth by an order of magnitude. This allows us to observe cavity-stimulated Raman emission that is highly spin-selective. Moreover, we demonstrate the first cases of cavity-enhanced optical nonlinearities in a solid-state Λ-system. This provides an all-optical, local method to control the spin exchange splitting. Incorporation of a highly engineerable quantum dot molecule into the photonic crystal architecture advances prospects for a quantum network.

DOI: 10.1038/ncomms8665

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