Flying spin qubits: A method for encoding and transporting qubits within a dimerized Heisenberg spin-12chain

Abstract

We present a method for encoding and transporting qubits within a dimerized Heisenberg spin-$\frac{1}{2}$ chain. Logical qubits are localized at the domain walls that separate the two possible dimerized states. The domain walls can be moved to produce ``flying spin qubits.'' The topological nature of these states makes them stable against local perturbations of the exchange profile. Pairs of domain walls can be used to generate Einstein-Podolsky-Rosen pairs of entangled qubits. We discuss speed limitations within an exactly solvable three-spin model and describe a possible physical realization using quantum dot arrays.