Spin decoherence in nanotube and graphene quantum dots

We show how to form spin qubits in carbon-based materials like graphene and
single-wall carbon nanotubes. For the former system, we discuss a new type of
long-distance coupling for solid-state spin qubits that is possible because of 
the narrow-gap and highly electron-hole-symmetric spectrum in graphene nanoribbons.
For the latter system, we analyze spin relaxation due to spin-orbit interaction (SOI)
and electron-phonon coupling. It turns out that the interplay of SOI in combination
with the one-dimensional nature of nanotubes results in a complex behavior with an
extremely wide range of relaxation rates. Most remarkably, at zero magnetic field,
the spin-orbit interaction induces a zero-field splitting in the energy spectrum that
can be functionalized for an all-electrical control of spin. Furthermore, we briefly
present our latest results on the spin decoherence in graphene and carbon nanotube
quantum dots due to hyperfine interaction with the surrounding C13 nuclei.

References:
B. Trauzettel, D.V. Bulaev, D. Loss, and G. Burkard, Nature Phys. 3, 192 (2007).
D.V. Bulaev, B. Trauzettel, and D. Loss, Phys. Rev. B 77, 235301 (2008).
J. Fischer, B. Trauzettel, and D. Loss, arXiv:0906.2800.