91 research outputs found
Charge noise analysis of an AlGaAs/GaAs quantum dot using transmission-type radio-frequency single-electron transistor technique
Radio-frequency (rf)- operated single-electron transistors (SETs) are
high-sensitivity, fast-response electrometers, which are valuable for
developing new insights into single-charge dynamics. We investigate
high-frequency (up to 1 MHz) charge noise in an AlGaAs/GaAs quantum dot using a
transmission-type rf-SET technique. The electron capture and emission kinetics
on a trap in the vicinity of the quantum dot are dominated by a Poisson
process. The maximum bandwidth for measuring single trapping events is about 1
MHz, which is the same as that required for observing single-electron tunneling
oscillations in a measurable current (~0.1pA).Comment: 4 pages, 4 figures, to be published in Appl. Phys. Let
Inelastic tunneling in a double quantum dot coupled to a bosonic environment
Coupling a quantum system to a bosonic environment always give rise to
inelastic processes, which reduce the coherency of the system. We measure
energy dependent rates for inelastic tunneling processes in a fully
controllable two-level system of a double quantum dot. The emission and
absorption rates are well repro-duced by Einstein's coefficients, which relate
to the spontaneous emission rate. The inelastic tunneling rate can be
comparable to the elastic tunneling rate if the boson occupation number becomes
large. In the specific semiconductor double dot, the energy dependence of the
inelastic rate suggests that acoustic phonons are coupled to the double dot
piezoelectrically.Comment: 6 pages, 4 figure
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