Description
Half-quantum vortices, each with flux of h/4e, are needed to
realize topological quantum computation in a p+ip
superconductor. However, until recently, there had not been
any clear experimental observation of such vortices. We
point out, although the magnetic energy is reduced by
breaking full vortices into half-quantum vortices, there is
an energy cost (which diverges with system size) due to the
unscreened spin current and the spin state locking. The
recent observation of half-quantum vortices by the Budakian
group can be best explained by the fact that the magnetic
energy savings can dominate over the spin energy cost in a
mesoscopic setting. A finite density vortex lattice may have
similar energetics, leading to a lattice of half-quantum
vortices. Lastly we show that there can be entropy driven
dissociation of a full vortex into two half-quantum vortices.
Primary author
Dr
Suk Bum Chung
(Stanford University)
