Sequential measurement-based quantum computing with memories

TL;DR

This paper proposes a flexible, memory-based sequential quantum computing scheme that reduces the spatial resources needed for universal computation, applicable to various quantum systems and ideal for atom-photon interface implementations.

Contribution

It introduces a unified, general framework for sequential measurement-based quantum computing using long-lived memories and short-lived moving systems, simplifying cluster state generation.

Findings

Universal quantum computation with only a one-dimensional array of memories.

Applicable to both discrete-variable and continuous-variable systems.

Framework encompasses and generalizes previous proposals.

Abstract

We introduce a general scheme for sequential one-way quantum computation where static systems with long-living quantum coherence (memories) interact with moving systems that may possess very short coherence times. Both the generation of the cluster state needed for the computation and its consumption by measurements are carried out simultaneously. As a consequence, effective clusters of one spatial dimension fewer than in the standard approach are sufficient for computation. In particular, universal computation requires only a one-dimensional array of memories. The scheme applies to discrete-variable systems of any dimension as well as to continuous-variable ones, and both are treated equivalently under the light of local complementation of graphs. In this way our formalism introduces a general framework that encompasses and generalizes in a unified manner some previous system-dependent proposals. The procedure is intrinsically well-suited for implementations with atom-photon interfaces.