Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 44: Poster Session: Quantum Dots and Wires - Transport & Optical Properties
HL 44.2: Poster
Dienstag, 27. März 2012, 09:30–12:30, Poster D
Real-time charge sensing analysis of metastable states in double quantum dots — •Martin Andreas Brühlmann1, Daniel Biesinger1, Dominik Zumbühl1, Jeramy Zimmerman2, and Art C. Gossard2 — 1Department of Physics, University of Basel, Switzerland — 2Materials Department, University of California, Santa Barbara, California, USA
We investigate metastable charge states in lateral GaAs few-electron double quantum dots using real-time charge sensing. We use adjacent quantum dots as highly-sensitive charge sensors with a rise time of a few ms and a very good signal-to-noise ratio. Observing the charge stability diagram at very low dot-reservoir tunneling rates of a few Hz, a well defined diamond-shaped area between the (0,0) and the (1,1) triple points appears, showing charge-switching between the (1,0) and (0,1) states as a function of time resulting in a telegraph-like signal.
To further study this telegraph diamond, we gather statistics of the tunneling events and extract tunnel rates as a function of gate voltage using an adaptive algorithm. It measures repeatedly the times the system remains in one state before switching to the other and extracts the tunneling rate from the histogram of those times. Detailed testing with computer generated data shows that the algorithm works properly within statistical accuracy and is only limited by the bandwidth of the setup.