Dresden 2014 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 65: Quantum Dots: Optical Properties II (organized by HL)

TT 65.1: Talk

Wednesday, April 2, 2014, 11:30–11:45, POT 251

Revealing the local environment noise of a quantum dot through resonance fluorescence intensity statistics — •Megan Stanley, Clemens Matthiesen, and Mete Atatüre — Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK

The electronic level structure and optical transitions of quantum dots are subject to fluctuating electric fields from nearby charge traps and a noisy Overhauser field from local nuclear spins [1]. The resultant inhomogeneous electron spin dephasing and reduced photon spectral purity are detrimental to the use of dots in quantum information processing [2]. We combine the intensity autocorrelation of resonance fluorescence (RF) and full photon counting statistics to capture the amplitudes and timescales of environment-induced fluctuations. Full counting statistics offer a robust and technically undemanding method to quantify steady-state spectral diffusion. In particular, it allows us to distinguish blinking or switching from continuous spectral shifts when this is not obvious from RF timetraces. Charge and nuclear spin contributions to noise are distinguished in autocorrelations via a detailed exploration of detuning and excitation power dependent sensitivities in comparison to a theoretical model. We find electric field noise to dominate down to timescales of 100us. Finally, we expose nuclear spin noise exclusively by decoupling the fluorescence from the electric field fluctuations using a two-colour noise compensation technique. [1] A. V. Kuhlmann et al., Nature Phys. 9, 570-575 (2013) [2] C. Santori et al., Nature 419, 594-597 (2002)