Fast and high-fidelity multi-qubit state transfer

We describe a new quantum walk formalism to bound the growth of quantum operators. We then apply these new mathematical tools to prove a linear light cone bound for non-interacting particles on a d-dimensional cubic lattice with power-law hopping. In particular, the dynamics is constrained within a linear light cone if α>d+1. We present an efficient protocol to perform quantum state transfer using Hamiltonian dynamics with long-range interactions. The time to transfer n qubits a sufficiently large distance is proportional to the square root of n. Even without error correction, the fidelity of this multi-qubit state transfer process remains finite for arbitrarily well-separated qubits in the presence of uncorrelated random errors in coupling constants.

Y. Hong and A. Lucas, "Fast high-fidelity multi-qubit state transfer with long-range interactions", arXiv:2009.06587 [quant-ph]