Perfect state transfers by selective quantum interferences within complex spin networks

TL;DR

This paper introduces a method for achieving perfect, directional quantum state transfer in complex spin networks by exploiting quantum interference effects and global control techniques, demonstrated on a 13C NMR system.

Contribution

It presents a novel approach to control quantum information flow in complex networks using interference and timing, enabling perfect state transfer with minimal local control.

Findings

Achieved perfect state transfer between selected spins in a complex network.

Demonstrated the method on a 13C NMR quantum simulator.

Controlled quantum information routing using global manipulations.

Abstract

We present a method that implement directional, perfect state transfers within a branched spin network by exploiting quantum interferences in the time-domain. That provides a tool to isolate subsystems from a large and complex one. Directionality is achieved by interrupting the spin-spin coupled evolution with periods of free Zeeman evolutions, whose timing is tuned to be commensurate with the relative phases accrued by specific spin pairs. This leads to a resonant transfer between the chosen qubits, and to a detuning of all remaining pathways in the network, using only global manipulations. As the transfer is perfect when the selected pathway is mediated by 2 or 3 spins, distant state transfers over complex networks can be achieved by successive recouplings among specific pairs/triads of spins. These effects are illustrated with a quantum simulator involving 13C NMR on Leucine's backbone; a six-spin network.