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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 (CC BY 3.0).

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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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