Dresden 2014 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 60: Quantum dots: Optical properties I (with TT)

HL 60.7: Vortrag

Mittwoch, 2. April 2014, 11:00–11:15, POT 251

Charge noise and spin noise in a semiconductor quantum device — •Andreas Kuhlmann1, Jonathan Prechtel1, Julien Houel1, Arne Ludwig1,2, Dirk Reuter2, Andreas Wieck2, Martino Poggio1, and Richard Warburton11University of Basel, Switzerland — 2Ruhr-Universität Bochum, Germany

Self-assembled QDs are potentially excellent single-photon sources. The linewidths are in the best case a factor of two larger than the transform-limit. Optimizing performance demands an understanding of noise and a strategy to circumvent its deleterious effects.

There are two sources of noise inherent to the semiconductor: charge noise and spin noise[1]. We present an investigation of noise in an ultra-clean semiconductor quantum device, using a minimally-invasive, ultra-sensitive, local probe: resonance fluorescence from a single QD. We present noise spectra with 6 decades of resolution in the noise power over 6 decades of frequency, from 0.1 Hz to 100 kHz. Significantly, we have discovered a spectroscopic way to distinguish charge noise from spin noise. We present a dynamic feedback technique to remove charge noise from the device[2]. We show that nuclear spin noise is the dominant dephasing mechanism that limits performance as a single-photon source. For the charged exciton, we demonstrate a significant decrease in the spin noise with resonant laser excitation. This noise reduction for the charged exciton is exploited to demonstrate transform-limited optical linewidths even when the measurement is performed very slowly.

[1] A. V. Kuhlmann et al., Nature Phys. 9, 570 (2013). [2] J. H. Prechtel et al., Phys. Rev. X 3, 041006 (2013).

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