Berlin 2014 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 44: Quantum information: Photons and nonclassical light II
Q 44.2: Vortrag
Donnerstag, 20. März 2014, 14:15–14:30, UDL HS3038
Measuring the local environment of a quantum dot — •Clemens Matthiesen, Megan Stanley, Jack Hansom, Claire Le Gall, and Mete Atature — Cavendish Laboratory, Department of Physics, University of Cambridge, UK
The electronic level structure and optical transitions of quantum dots (QDs) are subject to fluctuating electric fields from nearby charge traps and a noisy Overhauser field from local nuclear spins [1,2]. The resultant inhomogeneous electron spin dephasing and a reduced photon spectral purity are detrimental to the use of QDs in quantum information processing. Pulling together experimental results from intensity autocorrelations, counting statistics and high-resolution emission spectra of QD resonance fluorescence (RF), we obtain a detailed self-consistent picture of the environment dynamics. Full counting statistics quantify steady-state spectral diffusion and provide a means to distinguish blinking or switching from continuous spectral shifts. The intensity autocorrelation g(2) reveals noise amplitudes and their timescales and together with a theoretical model enables identification of the respective origins. We find electric field noise to be dominant down to a 100 µs timescale, while Overhauser field variations feature on faster timescales. High-resolution emission spectra offer a sensitive probe of the nuclear field dispersion, and, in agreement with the autocorrelations, point to a static Overhauser variance at different Rabi frequencies. [1] A. N. Vamivakas et al., Phys. Rev. Lett. 107, 166802 (2011) [2] A. V. Kuhlmann et al., Nature Phys. 9, 570-575 (2013)