Quantum computing via measurements only

TL;DR

This paper introduces a scalable quantum computing model that uses a pre-prepared entangled cluster state, where computation is performed solely through single-qubit measurements, simplifying the process compared to traditional gate-based models.

Contribution

The paper proposes a measurement-based quantum computing model utilizing cluster states, offering a scalable alternative to gate-sequence quantum computers.

Findings

Cluster states can be efficiently created in systems with quantum Ising interactions.

Quantum computation can be achieved through single-particle measurements on the cluster.

The model simplifies quantum computing by removing the need for controlled interactions during computation.

Abstract

A quantum computer promises efficient processing of certain computational tasks that are intractable with classical computer technology. While basic principles of a quantum computer have been demonstrated in the laboratory, scalability of these systems to a large number of qubits, essential for practical applications such as the Shor algorithm, represents a formidable challenge. Most of the current experiments are designed to implement sequences of highly controlled interactions between selected particles (qubits), thereby following models of a quantum computer as a (sequential) network of quantum logic gates. Here we propose a different model of a scalable quantum computer. In our model, the entire resource for the quantum computation is provided initially in form of a specific entangled state (a so-called cluster state) of a large number of qubits. Information is then written onto the cluster, processed, and read out form the cluster by one-particle measurements only. The entangled state of the cluster thus serves as a universal substrate for any quantum computation. Cluster states can be created efficiently in any system with a quantum Ising-type interaction (at very low temperatures) between two-state particles in a lattice configuration.