Resilience to Time-Correlated Noise in Quantum Computation

Fault-tolerant quantum computation techniques rely on weakly correlated noise. Here, I show that it is enough to assume weak spatial correlations: Time correlations can take any form. In particular, single-shot error-correction techniques exhibit a noise threshold for quantum memories under spatially local stochastic noise.

Popular Summary

Building a quantum computer is one of the greatest scientific and technological challenges of our time. The key obstacle to this endeavor is noise, which appears, for example, in the form of decoherence caused by interactions with the environment. Theoretical developments of fault-tolerant computing techniques have revealed that quantum computation is possible as long as noise is (i) weak enough and (ii) weakly correlated in space and time. Here, we focus on widening the range of systems suitable for quantum computation by considering stronger forms of noise, in particular, noise with arbitrary correlations in time.

We theoretically consider noise modeled stochastically and a quantum computation performed on a number of qubits. Focusing on quantum memories, we show that fault-tolerant quantum computation can still be achieved even when noise with arbitrary time correlations is present. Correlations that are arbitrary in time might be unavoidable in some systems in which, for example, some parts might fail permanently or for long periods of time. The key to achieving a strong resilience to noise is to perform error corrections over a short period of time using techniques inspired by the notion of confinement, which is of paramount importance in fundamental physics.

With our new approach, more physical systems become potential candidates for quantum computing. We expect that our findings will lessen the level of control required to perform quantum error corrections and motivate studies of other methods to ensure resilience against time-correlated errors.