12 research outputs found
Implementing quantum gates through scattering between a static and a flying qubit
We investigate whether a two-qubit quantum gate can be implemented in a
scattering process involving a flying and a static qubit. To this end, we focus
on a paradigmatic setup made out of a mobile particle and a quantum impurity,
whose respective spin degrees of freedom couple to each other during a
one-dimensional scattering process. Once a condition for the occurrence of
quantum gates is derived in terms of spin-dependent transmission coefficients,
we show that this can be actually fulfilled through the insertion of an
additional narrow potential barrier. An interesting observation is that under
resonance conditions the above enables a gate only for isotropic Heisenberg
(exchange) interactions and fails for an XY interaction. We show the existence
of parameter regimes for which gates able to establish a maximum amount of
entanglement can be implemented. The gates are found to be robust to variations
of the optimal parameters.Comment: 7 pages, 3 figure
Quantum Computing via The Bethe Ansatz
We recognize quantum circuit model of computation as factorisable scattering
model and propose that a quantum computer is associated with a quantum
many-body system solved by the Bethe ansatz. As an typical example to support
our perspectives on quantum computation, we study quantum computing in
one-dimensional nonrelativistic system with delta-function interaction, where
the two-body scattering matrix satisfies the factorisation equation (the
quantum Yang--Baxter equation) and acts as a parametric two-body quantum gate.
We conclude by comparing quantum computing via the factorisable scattering with
topological quantum computing.Comment: 6 pages. Comments welcom