Mixed-state quantum transport in correlated spin networks

TL;DR

This paper investigates quantum state transport in complex spin networks in mixed states, deriving conditions for perfect transfer and proposing engineered couplings to achieve it in realistic, non-ideal scenarios.

Contribution

It introduces explicit conditions for perfect quantum transport in mixed states and provides a Hamiltonian design for engineered couplings in complex networks.

Findings

Derived explicit conditions for perfect state transfer in mixed states.

Showed the necessity of phase correlation along all network paths.

Proposed a Hamiltonian for engineered couplings enabling perfect transport.

Abstract

Quantum spin networks can be used to transport information between separated registers in a quantum information processor. To find a practical implementation, the strict requirements of ideal models for perfect state transfer need to be relaxed, allowing for complex coupling topologies and general initial states. Here we analyze transport in complex quantum spin networks in the maximally mixed state and derive explicit conditions that should be satisfied by propagators for perfect state transport. Using a description of the transport process as a quantum walk over the network, we show that it is necessary to phase correlate the transport processes occurring along all the possible paths in the network. We provide a Hamiltonian that achieves this correlation, and use it in a constructive method to derive engineered couplings for perfect transport in complicated network topologies.