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Soutenance de thèse

Vendredi 13 mars 2015 à 14h00,
Salle des séminaire, bât A.

Orateur : Benoit Bertrand
"Long-range transfer of spin information using individual electrons"

Abstract :

Recently a growing interest emerged towards the use of electron spins for information processing. The current developments range from the generation of spin polarized currents to the coherent manipulation of single electron spins in quantum dots, with applications in spintronics and quantum information processing respectively.

The main objective of this thesis was to develop the equivalent of spintronics at the single electron level. For that purpose, we try to achieve the coherent transport of a single electron spin between distant quantum dots. This could be a promising means of interconnecting different nodes of a quantum nanoprocessor.

The electron transfer is ensured by a surface acoustic wave (SAW) that induces dynamical quantum dots thanks to the material piezoelectricity.

First, the injection of a single electron from a static to a dynamical quantum dot has been studied. It enables the control of single electron transfer with unity probability down to the nanosecond timescale, thanks to a fast engineering of the static confining potential.

Next, we demonstrate the possibility to prepare a coherent spin superposition, using an isolated double quantum dot in a metastable position that is compatible with SAW-assisted electron transfer. This type of isolated dot systems offers more liberty in terms of control. Taking advantage of this feature, a new scheme for coherent spin manipulations has been implemented and proved to have reduced noise sensitivity.

Finally, transfer of spin information encoded in one or two electrons has been achieved, with fidelities reaching 30%.

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