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Entropy 2010, 12(7), 1721-1732; doi:10.3390/e12071721

Measurement Back-Action in Quantum Point-Contact Charge Sensing

1,* , 1,2, 1, 1,3, 1, 4,5, 4, 6, 1,6, 7, 1 and 1
1 Solid State Physics Laboratory, ETH Zurich, Schafmattstr. 16, 8093 Zurich, Switzerland 2 Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA 3 EMPA, 8600 Dübendorf, Switzerland 4 Theoretische Physik, ETH Zurich, Wolfgang-Pauli-Str. 27, 8093 Zurich, Switzerland 5 Instituut-Lorentz, Universiteit Leiden, P.O. Box 9506, 2300 RA Leiden, The Netherlands 6 Institut für Experimentelle und Angewandte Physik, Universität Regensburg, 93040 Regensburg, Germany 7 FIRST Laboratory, ETH Zurich, Wolfgang-Pauli-Str. 10, 8093 Zurich, Switzerland
* Author to whom correspondence should be addressed.
Received: 10 May 2010 / Revised: 21 June 2010 / Accepted: 25 June 2010 / Published: 29 June 2010
(This article belongs to the Special Issue Quantum Information)
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Charge sensing with quantum point-contacts (QPCs) is a technique widely used in semiconductor quantum-dot research. Understanding the physics of this measurement process, as well as finding ways of suppressing unwanted measurement back-action, are therefore both desirable. In this article, we present experimental studies targeting these two goals. Firstly, we measure the effect of a QPC on electron tunneling between two InAs quantum dots, and show that a model based on the QPC’s shot-noise can account for it. Secondly, we discuss the possibility of lowering the measurement current (and thus the back-action) used for charge sensing by correlating the signals of two independent measurement channels. The performance of this method is tested in a typical experimental setup.
Keywords: quantum dots; quantum wires; noise; single-electron tunneling quantum dots; quantum wires; noise; single-electron tunneling
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Küng, B.; Gustavsson, S.; Choi, T.; Shorubalko, I.; Pfäffli, O.; Hassler, F.; Blatter, G.; Reinwald, M.; Wegscheider, W.; Schön, S.; Ihn, T.; Ensslin, K. Measurement Back-Action in Quantum Point-Contact Charge Sensing. Entropy 2010, 12, 1721-1732.

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