107 research outputs found
Coherent switching of semiconductor resonator solitons
We demonstrate switching on and off of spatial solitons in a semiconductor
microresonator by injection of light coherent with the background illumination.
Evidence results that the formation of the solitons and their switching does
not involve thermal processes.Comment: 3 pages, 5 figure
Noise at a Fermi-edge singularity
We present noise measurements of self-assembled InAs quantum dots at high
magnetic fields. In comparison to I-V characteristics at zero magnetic field we
notice a strong current overshoot which is due to a Fermi-edge singularity. We
observe an enhanced suppression in the shot noise power simultaneous to the
current overshoot which is attributed to the electron-electron interaction in
the Fermi-edge singularity
Enhanced quantized current driven by surface acoustic waves
We present the experimental realization of different approaches to increase
the amount of quantized current which is driven by surface acoustic waves
through split gate structures in a two dimensional electron gas. Samples with
driving frequencies of up to 4.7 GHz have been fabricated without a
deterioration of the precision of the current steps, and a parallelization of
two channels with correspondingly doubled current values have been achieved. We
discuss theoretical and technological limitations of these approaches for
metrological applications as well as for quantum logics.Comment: 3pages, 4eps-figure
Enhanced Shot Noise in Tunneling through a Stack of Coupled Quantum Dots
We have investigated the noise properties of the tunneling current through
vertically coupled self-assembled InAs quantum dots. We observe
super-Poissonian shot noise at low temperatures. For increased temperature this
effect is suppressed. The super-Poissonian noise is explained by capacitive
coupling between different stacks of quantum dots
Tuning the onset voltage of resonant tunneling through InAs quantum dots by growth parameters
We investigated the size dependence of the ground state energy in
self-assembled InAs quantum dots embedded in resonant tunneling diodes.
Individual current steps observed in the current-voltage characteristics are
attributed to resonant single-electron tunneling via the ground state of
individual InAs quantum dots. The onset voltage of the first step observed is
shown to decrease systematically from 200 mV to 0 with increasing InAs
coverage. We relate this to a coverage-dependent size of InAs dots grown on
AlAs. The results are confirmed by atomic force micrographs and
photoluminescence experiments on reference samples.Comment: 3 pages, 3 figure
Synchronized single electron emission from dynamical quantum dots
We study synchronized quantized charge pumping through several dynamical
quantum dots (QDs) driven by a single time modulated gate signal. We show that
the main obstacle for synchronization being the lack of uniformity can be
overcome by operating the QDs in the decay cascade regime. We discuss the
mechanism responsible for lifting the stringent uniformity requirements. This
enhanced functionality of dynamical QDs might find applications in
nanoelectronics and quantum metrology.Comment: 4 pages, 3 figures, submitted to AP
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