Perfect, pretty good and optimised quantum state transfer in transmon qubit chains

Abstract

Chains of transmon qubits are considered promising systems to implement different quantum information tasks.In particular as channels that perform high-quality quantum state transfer. We study how changing the interactionstrength between the chain qubits allows us to obtain perfect or pretty good state transfer and present explicitanalytic expressions for their transmission fidelity. For particular values of the interactions between the qubits,transmon chains are equivalent to generalized SSH chains and show the traditional traits observed in chains withtopological states, localized states at the extremes of the chain, and eigenvalues that lie inside the spectral gap.Consequently, we study the quantum state transfer on chains with dimerised interactions, looking for chains withfast transfer times. We show that, in many cases, asking for fast transfer times results in chains with dimerisedinteractions that do not have topological states.