483 research outputs found
Vortex Molecules in Spinor Condensates
Condensates of atoms with spins can have vortices of several types; these are
related to the symmetry group of the atoms' ground state. We discuss how, when
a condensate is placed in a small magnetic field that breaks the spin symmetry,
these vortices may form bound states. Using symmetry classification of
vortex-charge and rough estimates for vortex interactions, one can show that
some configurations that are stable at zero temperature can decay at finite
temperatures by crossing over energy barriers. Our focus is cyclic spin 2
condensates, which have tetrahedral symmetry.Comment: 28 pages, 12 figure
Observing Majorana Bound States in p-wave Superconductors Using Noise Measurements in Tunneling Experiments
The zero-energy bound states at the edges or vortex cores of chiral p-wave
superconductors should behave like majorana fermions. We introduce a model
Hamiltonian that describes the tunnelling process when electrons are injected
into such states. Using a non-equilibrium green function formalism, we find
exact analytic expressions for the tunnelling current and noise and identify
experimental signatures of the majorana nature of the bound states to be found
in the shot noise. We discuss the results in the context of different candidate
materials that support triplet superconductivity. Experimental verification of
the majorana character of midgap states would have important implications for
the prospects of topological quantum computation.Comment: 4 pages, 1 figur
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