J. R. Williams, A. J. Bestwick, P. Gallagher, Seung Sae Hong, Y. Cui, Andrew S. Bleich, J. G. Analytis, I. R. Fisher, D. Goldhaber-Gordon
The ability to measure and manipulate complex particles in the solid state is
a cornerstone of modern condensed-matter physics. Typical excitations of a sea
of electrons, called quasiparticles, have properties similar to those of free
electrons. However, in recent years exotic excitations with very different
properties have been created in designer quantum materials, including Dirac
fermions in graphene [1] and fractionally charged quasiparticles in fractional
quantum Hall systems [2]. Here we report signatures of a new quasiparticle --
the Majorana fermion -- in Josephson junctions consisting of two
superconducting leads coupled through a three-dimensional topological insulator
[3]. We observe two striking departures from the common transport properties of
Josephson junctions: a characteristic energy that scales inversely with the
width of the junction, and a low characteristic magnetic field for suppressing
supercurrent. To explain these effects, we propose a phenomenological model in
which a one-dimensional wire of Majorana fermions is present along the width of
the junction, similar to a theoretical prediction by Fu and Kane [4]. These
results present an opening into the investigation of Majorana fermions in the
solid state and their exotic properties, including non-Abelian statistics [5],
a suggested basis for fault-tolerant quantum computation [6].
View original:
http://arxiv.org/abs/1202.2323
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