Quantum states experimentally achieving high-fidelity transmission over a spin chain

TL;DR

This paper proposes a method to determine optimal initial quantum states for high-fidelity transmission in spin chains, demonstrating near-perfect transfer with a specific three-spin encoding and explaining previous experimental results.

Contribution

It introduces a novel approach to identify initial states for quantum state transfer in spin chains, including the experimentally implemented double quantum Hamiltonian.

Findings

Supports high-fidelity transfer with a three-spin initial encoding

Fidelity decreases slowly with increasing chain length

Explains previous experimental results of exceptional transfer

Abstract

A uniformly coupled double quantum Hamiltonian for a spin chain has recently been implemented experimentally. We propose a method for the determination of initial quantum states that will provide perfect or near-perfect state transmission for an arbitrary Hamiltonian including this one. By calculating the eigenvalues and eigenvectors of a unitary operator obtained from the free evolution plus an exchange operator, we find that the double quantum Hamiltonian spin chain will support a three-spin initial encoding that will transfer along the chain with remarkably high fidelity. The fidelity is also found to decrease very slowly with increasing chain length. In addition, we are able to explain previous results showing exceptional transfer using this method.