Time-Domain Multiplexed 2-Dimensional Cluster State: Universal Quantum Computing Platform

TL;DR

This paper reports the first experimental realization of a scalable 2D cluster state using time-domain multiplexing, enabling universal measurement-based quantum computation with continuous-variable optical systems.

Contribution

It introduces a novel scalable 2D cluster state for universal MBQC, demonstrated via time-domain multiplexing with continuous-variable optical modes.

Findings

Generated and verified a 2D cluster state for about 5,000 operations

Proved the universality of the 2D cluster state for MBQC

Demonstrated scalability independent of coherence time constraints

Abstract

Quantum computation promises applications that are thought to be impossible with classical computation. To realize practical quantum computation, the following three properties will be necessary: universality, scalability, and fault-tolerance. Universality is the ability to execute arbitrary multi-input quantum algorithms. Scalability means that computational resources such as logical qubits can be increased without requiring exponential increase in physical resources. Lastly, fault-tolerance is the ability to perform quantum algorithms in presence of imperfections and noise. A promising approach to scalability was demonstrated with the generation of one-million-mode 1-dimensional cluster state, a resource for one-input computation in measurement-based quantum computation (MBQC). The demonstration was based on time-domain multiplexing (TDM) approach using continuous-variable (CV) optical flying qumodes (CV analogue of qubit). Demonstrating universality, however, has been a challenging task for any physical system and approach. Here, we present, for the first time among any physical system, experimental realization of a scalable resource state for universal MBQC: a 2-dimensional cluster state. We also prove the universality and give the methodology for utilizing this state in MBQC. Our state is based on TDM approach that allows unlimited resource generation regardless of the coherence time of the system. As a demonstration of our method, we generate and verify a 2-dimensional cluster state capable of about 5,000 operation steps on 5 inputs.