Universal set of Dynamically Protected Gates for Bipartite Qubit Networks II: Soft Pulse Implementation of the [[5,1,3]] Quantum Error Correcting Code

TL;DR

This paper demonstrates that combining dynamical decoupling with quantum error correction using a five-qubit code significantly enhances qubit coherence in a network with always-on couplings, through soft pulse implementations.

Contribution

It introduces a soft pulse implementation of universal quantum gates that enable effective dynamical decoupling and error correction in a bipartite qubit network with always-on interactions.

Findings

QEC alone reduces infidelity by over an order of magnitude.

Combined DD/QEC protocol further improves coherence dramatically.

Simulation of six-qubit dynamics over tens of thousands of pulses confirms effectiveness.

Abstract

We model repetitive quantum error correction (QEC) with the single-error-correcting five-qubit code on a network of individually-controlled qubits with always-on Ising couplings, using our previously designed universal set of quantum gates based on sequences of shaped decoupling pulses. In addition to serving as accurate quantum gates, the sequences also provide dynamical decoupling (DD) of low-frequency phase noise. The simulation involves integrating unitary dynamics of six qubits over the duration of tens of thousands of control pulses, using classical stochastic phase noise as a source of decoherence. The combined DD/QEC protocol dramatically improves the coherence, with the QEC alone responsible for more than an order of magnitude infidelity reduction.