An Evaluation of the Remote CX Protocol under Noise in Distributed Quantum Computing

TL;DR

This paper evaluates the performance of the remote CX protocol in distributed quantum computing under noisy conditions, analyzing how network configurations and qubit assignment strategies affect fidelity in various quantum circuits.

Contribution

It introduces a high-level simulation framework to assess the impact of noise on the remote CX protocol across different network setups and qubit assignment strategies.

Findings

Naive and graph partitioning strategies affect fidelity differently.

Network noise degrades performance depending on configuration.

Insights into optimal QPU and network setups for better fidelity.

Abstract

Quantum computers connected through classical and quantum communication channels can be combined to function as a single unit to run large quantum circuits that each device is unable to execute on their own. The distributed quantum computing paradigm is therefore often seen as a potential pathway to scaling quantum computing to capacities necessary for practical and large-scale applications. Whether connecting multiple quantum processing units (QPUs) in clusters or over networks, quantum communication requires entanglement to be generated and distributed over distances. Using entanglement, the remote CX protocol can be performed, which allows the application of the CX gate involving qubits located in different QPUs. In this work, we use a specialized simulation framework for a high-level evaluation of the impact of the protocol when executed under noise in various network configurations using different number of QPUs. We compare naive and graph partitioning qubit assignment strategies and how they affect the fidelity in experiments run on Grover, GHZ, VQC, and random circuits. The results provide insights on how QPU and network configurations or naive scheduling can degrade performance.