Issue
Europhys. Lett.
Volume 73, Number 5, March 2006
Page(s) 677 - 683
Section General
DOI http://dx.doi.org/10.1209/epl/i2005-10458-6
Published online 25 January 2006
Europhys. Lett., 73 (5), pp. 677-683 (2006)
DOI: 10.1209/epl/i2005-10458-6

All-electronic coherent population trapping in quantum dots

B. Michaelis1, C. Emary2 and C. W. J. Beenakker1

1  Instituut-Lorentz, Universiteit Leiden - P.O. Box 9506 2300 RA Leiden, The Netherlands
2  Department of Physics, University of California San Diego La Jolla, CA 92093-0319, USA


received 18 November 2005; accepted in final form 10 January 2006
published online 25 January 2006

Abstract
We present a fully electronic analogue of coherent population trapping in quantum optics, based on destructive interference of single-electron tunneling between three quantum dots. A large bias voltage plays the role of the laser illumination. The trapped state is a coherent superposition of the electronic charge in two of these quantum dots, so it is destabilized as a result of decoherence by coupling to external charges. The resulting current I through the device depends on the ratio of the decoherence rate $\Gamma_{\phi}$ and the tunneling rates. For $\Gamma_{\phi}\rightarrow 0$ one has simply $I=e\Gamma_{\phi}$. With increasing $\Gamma_{\phi}$ the current peaks at the inverse trapping time. The direct relation between I and $\Gamma_{\phi}$ can serve as a means of measuring the coherence time of a charge qubit in a transport experiment.

PACS
03.65.Yz - Decoherence; open systems; quantum statistical methods.
73.21.La - Quantum dots.
73.23.Hk - Coulomb blockade; single-electron tunneling.

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