Theoretical Physics

6 March 2013
Time: 15:00 to 16:00
Location:

Mark Elkin

Spin Transport In Carbon Nanotube Quantum Dots



Due to the lack of nuclear spin of the main Carbon isotope C12 and their predicted long coherence lengths carbon nanotubes seem ideal for use in spintronic devices, in which the spin degree of freedom of electrons is used to control transport. The classic example of which is a spin-valve, where transport between two ferromagnetic (FM) layers via an intermediary material is dependent on the relative magnetisation and hence the spin polarisations of the FM layers. Experiments using nanotubes as the intermediary material in spin valve structures have shown evidence of spin transport and experiments on FM contacted nanotube quantum dots have shown that their spin transport is dependent on the quantised energy levels within the QDs.

While the low-temperatures needed for nanotube spin transport means they are not suited for large-scale spintronics applications, their long phase coherence lengths make them a very suitable material for the study of solid-state quantum information. Recently progress has been made on realising a solid state entanglement measurement, as proposed by Loss, Oliver and Bena, where the cooper pairs from a superconducting electrode split into two lengths of Carbon nanotube, however it is currently unknown if the pairs remain entangled, for which the solid state equivalent of a Bell state measurement needs to be performed, for which the spin projection of split cooper pairs needs to be measured with respect to two FM electrodes whose relative magnetic orientations need to be controllable.

 

 

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