Role of interference in quantum state transfer through spin chains

We examine the role that interference plays in quantum state transfer through several types of finite spin chains, including chains with isotropic Heisenberg interaction between nearest neighbors, chains with reduced coupling constants to the spins at the end of the chain, and chains with anisotropic coupling constants. We evaluate quantitatively both the interference corresponding to the propagation of the entire chain and the interference in the effective propagation of the first and last spins only, treating the rest of the chain as a black box. We show that perfect quantum state transfer is possible without quantum interference and provide evidence that the spin chains examined realize interference-free quantum state transfer to a good approximation.