Atomicity in Distributed Quantum Computing

TL;DR

This paper initiates the formal study of atomicity in distributed quantum computing, establishing a model and showing local actions can be considered atomic based on observable dynamics despite quantum challenges.

Contribution

It introduces a formal model for distributed quantum systems and extends atomicity concepts to quantum computing, addressing challenges from entanglement and measurement.

Findings

Local actions are effectively atomic in observable dynamics.

A formal model for distributed quantum systems is established.

Quantum-specific challenges to atomicity are addressed.

Abstract

Atomicity is a ubiquitous assumption in distributed computing, under which actions are indivisible and appear sequential. In classical computing, this assumption has several theoretical and practical guarantees. In quantum computing, although atomicity is still commonly assumed, it has not been seriously studied, and a rigorous basis for it is missing. Classical results on atomicity do not directly carry over to distributed quantum computing, due to new challenges caused by quantum entanglement and the measurement problem from the underlying quantum mechanics. In this paper, we initiate the study of atomicity in distributed quantum computing. A formal model of (non-atomic) distributed quantum system is established. Based on the Dijkstra-Lamport condition, the system dynamics and observable dynamics of a distributed quantum system are defined, which correspond to the quantum state of and classically observable events in the system, respectively. Within this framework, we prove that local actions can be regarded as if they were atomic, up to the observable dynamics of the system.