Van der Waals-Zeeman Colloquium

Tuesday, 28 Nov 2006, 16:00h

Coherent control and read-out of a single electron spin in a quantum dot

Dr. Lieven Vandersypen
Kavli Institute of NanoScience, Delft Univ. of Technology

The ability to control the state of individual quantum systems is at the heart of recent developments towards a scalable quantum computer. In this talk, I will show that all the basic elements for a quantum computer have been realized with electron spins in GaAs quantum dot. These include various methods for single-shot read-out, coherent control of a single spin via magnetic resonance (both in Delft) and the coherent exchange of two coupled spins (at Harvard). In addition, we now understand the dominant relaxation and decoherence mechanisms, and relaxation times >100 ms and decoherence times > 1 µs have been observed. These timescales are mostly limited by the host material for the quantum dot. As an alternative to GaAs that may permit even longer spin coherence times, carbon is very attractive, and are now studying whether suitable quantum dots can be defined in single or bilayers of graphene. More broadly, we investigate the behavior of Dirac electrons in mesoscopic graphene.