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.
Highlights
The integration of InAs/GaAs quantum dots into nanophotonic cavities has led to impressive demonstrations of cavity quantum electrodynamics
The system consists of an InAs/GaAs QD molecule (QDM) embedded within an L3 cavity of a GaAs photonic crystal membrane (Fig. 1a,b)
The QDM structure was designed so that the energy levels are in resonance at a diode voltage for which two electrons are stable within the QDM21
Summary
The integration of InAs/GaAs quantum dots into nanophotonic cavities has led to impressive demonstrations of cavity quantum electrodynamics. 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 L-system where the ground-state spin splitting exceeds the cavity linewidth by an order of magnitude. A limitation of QDs is that the Zeeman splittings are small compared with typical cavity linewidths This makes it difficult to use the cavity for selective enhancement of one L branch, which is important for achieving spin–cavity interactions. An applied bias charges the molecule with two electrons, and the resulting two-spin system has an exchange splitting of 1.45 meV, almost an order of magnitude larger than the 0.19 meV cavity linewidth This is a new spectroscopic regime for cavity-coupled QDs, where the cavity can be coupled exclusively to either the excitation branch or the emission branch of the L-system. Tuning the cavity to the excitation branch, we drive the QDM system strongly into the nonlinear regime to investigate the Autler–Townes state dressing and laser-induced control of the spin exchange energy
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
