ETD

• bosonizzazione
• effetto josephson
• liquidi di luttinger
• nanotubi

In this work we wish to study from a theoretical point of view the transport
properties of metallic carbon nanotubes coupled to superconducting leads. In
particular we wish to study the Josephson effect that consists of a supercurrent
flowing among two superconductors through an insulating barrier (M. Tinkham ,
Introduction to Superconductivity , 1996) due to coherent propagation of
Cooper pairs. The current that can flow has a sine dependence on the phase
difference of the two superconductors and the maximum current (or critical current)
is found to decay exponentially with the separation of the superconducting
systems. If the coupling among the two superconductors is realized with a onedimensional
conductor (the contacts with the superconductors are treated as
tunnel barriers) the critical current is found to decay as a power law of the
separation at zero temperature (R. Fazio et Al. , Physical Review B 53 , 6653
(1996)), making this kind of couplings of potential technological interest.
Since electron–electron interactions play a prominent role in this effect, it is
interesting to study what happens when using carbon nanotubes as linking conductors;
this implementation has been studied experimentally in a recent work
(P. Jarillo-Herrero et Al , Nature 439 , 953 (2006)).