All-electronic coherent population trapping in quantum dots

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: 10 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 and the tunneling rates. For one has simply . With increasing the current peaks at the inverse trapping time. The direct relation between I and can serve as a means of measuring the coherence time of a charge qubit in a transport experiment.