Simultaneous multiple-user quantum communication across a spin-chain channel

Abstract

The time evolution of spin chains has been extensively studied for transferring quantum states between different registers of a quantum computer. Nonetheless, in most of these protocols only one sender-receiver pair can share the channel at each time. This significantly limits the rate of communication in a network of many users because they can only communicate through their common data-bus sequentially and not all at the same time. Here, we propose a protocol in which multiple users can share a spin chain channel simultaneously without having crosstalk between different parties. This is achieved by properly tuning the local parameters of the Hamiltonian to mediate an effective interaction between each pair of users via a distinct set of energy eigenstates of the system. We introduce three strategies with different levels of Hamiltonian tuning; each might be suitable for a different physical platform. All the three strategies provide very high transmission fidelities with vanishingly small crosstalk. The protocol is robust against various imperfections and we specifically show that our protocol can be experimentally realized on currently available superconducting quantum simulators.