Parallel entangling gate operations and two-way quantum communication in spin chains

TL;DR

This paper introduces a protocol for parallel two-qubit entangling gates using a shared spin chain, enabling faster quantum operations and two-way communication without crosstalk, robust against system size and disorder.

Contribution

It presents a novel method to perform multiple entangling gates simultaneously via Hamiltonian tuning, enhancing quantum circuit depth and communication capabilities.

Findings

Protocol enables parallel entangling gates with minimal crosstalk.

Performance remains robust with increasing system size and disorder.

Applicable to superconductor-based quantum systems.

Abstract

The power of a quantum circuit is determined through the number of two-qubit entangling gates that can be performed within the coherence time of the system. In the absence of parallel quantum gate operations, this would make the quantum simulators limited to shallow circuits. Here, we propose a protocol to parallelize the implementation of two-qubit entangling gates between multiple users which are spatially separated, and use a commonly shared spin chain data-bus. Our protocol works through inducing effective interaction between each pair of qubits without disturbing the others, therefore, it increases the rate of gate operations without creating crosstalk. This is achieved by tuning the Hamiltonian parameters appropriately, described in the form of two different strategies. The tuning of the parameters makes different bilocalized eigenstates responsible for the realization of the entangling gates between different pairs of distant qubits. Remarkably, the performance of our protocol is robust against increasing the length of the data-bus and the number of users. Moreover, we show that this protocol can tolerate various types of disorders and is applicable in the context of superconductor-based systems. The proposed protocol can serve for realizing two-way quantum communication.