Flying Spin Qubits

We present a method for encoding and transporting qubits within a dimerized Heisenberg spin-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 a wide class of perturbations. Pairs of domain walls can be used to generate Einstein-Podolsky-Rosen pairs of entangled qubits which may be used for quantum teleportation, dense coding, and other protocols. We discuss speed limitations within an exactly solvable three-spin model and describe a possible physical realization using quantum dot arrays