Quantum interference in carbon nanotubes

We present magnetotransport properties of a multiwalled carbon nanotube. We have developed a technique using electron beam lithography to connect a ca rbon nanotube with a small contact resistance. The temperature dependence o f the nanotube is thermally activated down to 30 mK but with multiple energ y gap. At low temperature, the magnetoconductance can be analysed in terms of quantum interferences. Both weak localisation and universal conductance fluctuations have been observed. The phase coherence length extracted from the weak localisation is consistent with the amplitude of the conductance f luctuations. (C) Academie des sciences/Elsevier, Paris.