High-order cumulants in the counting statistics of asymmetric quantum dots

Measurements of single electron tunneling through a quantum dot using a quantum point contact as charge detector have been performed for very long time traces with very large event counts. This large statistical basis is used for a detailed examination of the counting statistics for varying symmetry of the quantum dot system. From the measured statistics we extract high order cumulants describing the distribution. Oscillations of the high order cumulants are observed when varying the symmetry. We compare this behavior to the observed oscillation in time dependence and show that the variation of both system variables lead to the same kind of oscillating response.Comment: 3 page

A self-referenced single-electron current source

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A quantized current source with mesoscopic feedback

We study a mesoscopic circuit of two quantized current sources, realized by non-adiabatic single- electron pumps connected in series with a small micron-sized island in between. We find that quantum transport through the second pump can be locked onto the quantized current of the first one by a feedback due to charging of the mesoscopic island. This is confirmed by a measurement of the charge variation on the island using a nearby charge detector. Finally, the charge feedback signal clearly evidences loading into excited states of the dynamic quantum dot during single-electron pump operation

Prediction of warping in thermoplastic AFP-manufactured laminates through simulation and experimentation

The thermoplastic automated fibre placement (T-AFP) process is a non-autoclave method for in-situ consolidation of thermoplastic composite material on a piecewise constructed laminate. High thermal gradients and nonlinear material behaviour, especially due to crystallization, make predic-tions of process-induced stress and warping difficult. This paper describes a method for simulating parts manufactured by T-AFP using a detailed material model to capture the dynamic nature of the process. The material model is flexible and can be altered to describe different semi-crystalline matrices, in this study focusing on low-melt polyaryletherketone (LM-PAEK). Two laminate panels are simulated within this work and assess the impact of a heated tooling on overall part warping. Panel warping is validated by performing 3D-scans of T-AFP-manufactured laminates produced using the same parameters as the simulation. The results show a good match between numeric and experimental warping, especially for heated tools, thus providing a useful method for predict-ing laminate warping and reducing the demand on manufacturing experimentation

Aerogel Waveplates

Optical transmission measurements were made on 98% porosity silica aerogel samples under various degrees of uniaxial strain. Uniaxially compressed aerogels exhibit large birefringence, proportional to the amount of compression, up to the 15% strain studied. The birefringence is mostly reversible and reproducible through multiple compression-decompression cycles. Our study demonstrates that uniaxially strained high porosity aerogels can be used as tunable waveplates in a broad spectral range.Comment: 7 pages, 4 figures, submitted to Optics Expres

Partitioning of on-demand electron pairs

We demonstrate the high fidelity splitting of electron pairs emitted on demand from a dynamic quantum dot by an electronic beam splitter. The fidelity of pair splitting is inferred from the coincidence of arrival in two detector paths probed by a measurement of the partitioning noise. The emission characteristic of the on-demand electron source is tunable from electrons being partitioned equally and independently to electron pairs being split with a fidelity of 90%. For low beam splitter transmittance we further find evidence of pair bunching violating statistical expectations for independent fermions