Nonequilibrium probing of two-level charge fluctuators using the step response of a single-electron transistor
Journal article, 2014

We report a new method to study two-level fluctuators (TLFs) by measuring the offset charge induced after applying a sudden step voltage to the gate electrode of a single-electron transistor. The offset charge is measured for more than 20 h for samples made on three different substrates. We find that the offset charge drift follows a logarithmic increase over 4 orders of magnitude in time and that the logarithmic slope increases linearly with the step voltage. The charge drift is independent of temperature, ruling out thermally activated TLFs and demonstrating that the charge fluctuations involve tunneling. These observations are in agreement with expectations for an ensemble of TLFs driven out of equilibrium. From our model, we extract the density of TLFs assuming either a volume density or a surface density.


Arsalan Pourkabirian

Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics

Martin Gustafsson

Chalmers, Microtechnology and Nanoscience (MC2), Quantum Device Physics

Göran Johansson

Chalmers, Microtechnology and Nanoscience (MC2), Applied Quantum Physics

John Clarke

Chalmers, Microtechnology and Nanoscience (MC2)

Per Delsing

Chalmers, Microtechnology and Nanoscience (MC2), Quantum Device Physics

Physical Review Letters

0031-9007 (ISSN) 1079-7114 (eISSN)

Vol. 113 25 256801- 256801

Areas of Advance

Nanoscience and Nanotechnology

Subject Categories

Nano Technology

Condensed Matter Physics


Nanofabrication Laboratory



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