99%-fidelity ballistic quantum-state transfer through long uniform channels

Abstract

Quantum-state transfer with fidelity higher than 0.99 can be achieved in the ballistic regime of an arbitrarily long one-dimensional chain with uniform nearest-neighbor interaction, except for the two pairs of mirror-symmetric extremal bonds, say x (first and last) and y (second and penultimate). These have to be roughly tuned to suitable values x ∼ 2N−1/3 and y ∼ 23/4N−1/6, where N is the chain length. The general framework can describe the end-to-end response in different models, such as fermion or boson hopping models and XX spin chains.