1,278 research outputs found
Topological Quantum Computing with p-Wave Superfluid Vortices
It is shown that Majorana fermions trapped in three vortices in a p-wave
superfluid form a qubit in a topological quantum computing (TQC). Several
similar ideas have already been proposed: Ivanov [Phys. Rev. Lett. {\bf 86},
268 (2001)] and Zhang {\it et al.} [Phys. Rev. Lett. {\bf 99}, 220502 (2007)]
have proposed schemes in which a qubit is implemented with two and four
Majorana fermions, respectively, where a qubit operation is performed by
exchanging the positions of Majorana fermions. The set of gates thus obtained
is a discrete subset of the relevant unitary group. We propose, in this paper,
a new scheme, where three Majorana fermions form a qubit. We show that
continuous 1-qubit gate operations are possible by exchanging the positions of
Majorana fermions complemented with dynamical phase change. 2-qubit gates are
realized through the use of the coupling between Majorana fermions of different
qubits.Comment: 5 pages, 2 figures. Two-qubit gate implementation is added
Holomorphic extension of the de Gennes function
This note is devoted to prove that the de Gennes function has a holomorphic
extension on a strip containing the real axis
Quantum Interference Phenomena Between Impurity States in d-wave Superconductors
We investigate the mutual influence of impurities in two-dimensional d-wave
superconductors involving self-consistent solutions of the Bogoliubov-de Gennes
equations. The local order parameter suppression, the local density of states
(LDOS) as well as the interference of impurity-induced structures are analyzed.
We employ an impurity position averaging scheme for the DOS that does not
neglect these interference effects, as the commonly used -matrix approaches
do.Comment: 4 eps figures, presented at SNS200
Lattice two-point functions and conformal invariance
A new realization of the conformal algebra is studied which mimics the
behaviour of a statistical system on a discrete albeit infinite lattice. The
two-point function is found from the requirement that it transforms covariantly
under this realization. The result is in agreement with explicit lattice
calculations of the Ising model and the dimensional spherical
model. A hard core is found which is not present in the continuum. For a
semi-infinite lattice, profiles are also obtained.Comment: 5 pages, plain Tex with IOP macros, no figure
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