Double quantum dots in carbon nanotubes

POSTER

Abstract

We study the behavior of few-electrons confined in a double-well quantum dot in semiconducting carbon nanotubes. These carbon nanostructures exhibit richer physics than GaAs ones due to the additional valley degree of freedom. We calculate and characterize the low energy eigenstates in the presence of a magnetic field and double-well detuning. Spin-orbit coupling lifts the spin and valley degeneracy and, in the presence of exchange interactions, leads, at small detunings and weak magnetic fields, to a spin-valley antisymmetric two-electron ground state which is not a pure spin-singlet state. At large detuning, the strong Coulomb interactions accessible in carbon nanotubes can substantially modify the non-interacting eigenstates via higher orbital-level mixing. The latter manifest in current transport experiments by the disappearance of the Pauli blockade.

Authors

  • Javier von Stecher

    JILA/Univ. of Colorado, JILA and Department of Physics, University of Colorado, Boulder, Colorado

  • Bernhard Wunsch

    Physics Department, Harvard University, Harvard University, Physics Department, Harvard University, Cambridge-MA, 20138.

  • Mikahil Lukin

    Harvard University, Physics Department, Harvard University, Cambridge-MA, 20138

  • Eugene Demler

    Physics Department, Harvard University, Cambridge, MA 02138, USA, Harvard University, Physics Department, Harvard University, Cambridge-MA, 20138

  • Ana Maria Rey

    JILA and University of Colorado at Boulder, JILA, NIST, JILA, NIST and Department of Physics, University of Colorado, Boulder, USA, JILA and Department of Physics, University of Colorado, Boulder, Colorado