May 30 2007
The electrical current circulating in usual electronic devices results from the motion of tens of thousands of charges. By reducing further the device sizes up to the manipulation of single charges, one could access new regimes of electronic transport where quantum mechanics would play an essential part. The perspectives are the realization of electronic devices able to process quantum information (quantum cryptography, quantum computing…).
In this prospect, the Mesoscopic Physics Group of the Laboratoire Pierre Aigrain has realized the first time-controlled single electron source on nanosecond timescales allowing for coherent manipulations of electrons in ballistic conductors. This result, published May 25 2007 in Science, was obtained using a quantum dot (designed in collaboration with the Laboratoire de Photonique et Nanostructures of CNRS-Marcoussis) coupled to the quantum conductor by a small constriction of controllable transmission. By varying the dot potential, the number of charges transferred to the circuit can be controlled. Measurements of the monoelectronic current in time and frequency domain have demonstrated the controlled injection of single electrons and allowed the extraction of the escape time on two orders of magnitude, from 0.1 to 10 ns. This source, or the combination of several synchronized sources, opens the way to new types of quantum experiments with electrons in analogy with those realized with photons.
An On-Demand Coherent Single Electron Source
Fève G., Mahé A., Berroir J.-M., Kontos T., Plaçais B., Glattli C., Cavanna
A., Etienne B., Jin Y.
Science, 316, 1169 (2007)