Electrical control of spontaneous emission and strong coupling for a single quantum dot

By A. Laucht, F. Hofbauer, N. Hauke, J. Angelé, S. Stobbe, M. Kaniber, G. Bohm, P. Lodahl, M. Amann, J. J. F. W. S. Institut and 6 more. 2008

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We report the design, fabrication and optical investigation of electrically tunable single quantum dots—photonic crystal defect nanocavities operating in both the weak and strong coupling regimes of the light–matter interaction. Unlike previous studies where the dot–cavity spectral detuning was varied by changing the lattice temperature, or by the adsorption of inert gases at low temperatures, we demonstrate that the quantum-confined Stark effect can be employed to quickly and reversibly switch the dot–cavity coupling simply by varying a gate voltage. Our results show that exciton transitions from individual dots can be tuned by ∼4 meV relative to the nanocavity mode before the emission quenches due to carrier tunneling escape. This range is much larger than the typical linewidth of the high-Q cavity modes (∼100 μeV) allowing us to explore and contrast regimes where the dots couple to the cavity or decay by spontaneous emission into the two-dimensional photonic bandgap. In the weak-coupling regime, we show that the dot spontaneous emission rate can be tuned using a gate voltage, with Purcell factors ⩾7. New information is obtained on the nature of the dot–cavity coupling in the weak coupling regime, and electrical control of zero-dimensional polaritons is demonstrated for the highest-Q cavities (Q⩾12 000). Vacuum Rabi splittings up to ∼120 μeV are observed, larger than the linewidths of either the decoupled exciton (γ⩽40 μeV) or cavity mode. These observations represent a voltage switchable optical nonlinearity at the single photon level, paving the way towards on-chip dot-based nano-photonic devices that can be integrated with passive optical components.

Subfields: Atomic and Molecular Physics, and Optics, Electrical and Electronic Engineering

View Paper: https://www.semanticscholar.org/paper/52c44ed37bd4dcf112e76bd5c41d2322b7d195b4

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In Atomic and Molecular Physics, and Optics

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Citations in the corpus

Quantum matter built from nanoscopic lattices of atoms and photons (2018, background): “…atomlike solid-state emitters such as quantum dots with small lithographically fabricated cavities (Pelton et al., 2002), and PCCs with diffraction-limited mode volumes rapidly emerged as a leading approach (Yoshie et al., 2004; Badolato et al., 2005; Fushman et al., 2008; Laucht et al., 2009).”