Thermal States as Universal Resources for Quantum Computation with Always-on Interactions

TL;DR

This paper demonstrates that measurement-based quantum computation can be performed on thermal states with always-on interactions, and that thermal errors can be corrected for fault-tolerance below a certain temperature.

Contribution

It introduces a model Hamiltonian showing universal quantum computation on thermal states without switching off interactions.

Findings

Quantum computation is achievable on thermal states with always-on interactions.

Thermal errors can be corrected, enabling fault-tolerant quantum computation.

A temperature threshold exists below which errors are manageable.

Abstract

Measurement-based quantum computation utilizes an initial entangled resource state and proceeds with subsequent single-qubit measurements. It is implicitly assumed that the interactions between qubits can be switched off so that the dynamics of the measured qubits do not affect the computation. By proposing a model spin Hamiltonian, we demonstrate that measurement-based quantum computation can be achieved on a thermal state with always-on interactions. Moreover, computational errors induced by thermal fluctuations can be corrected and thus the computation can be executed fault-tolerantly if the temperature is below a threshold value.