Quantum error correction for unresolvable spin ensemble

TL;DR

This paper introduces quantum error correction schemes for unresolvable spin ensembles that protect quantum information against various errors using collective measurements, enhancing memory and sensing capabilities.

Contribution

It proposes novel QEC codes for unresolvable ensembles that do not require individual qubit addressing, enabling practical error correction in realistic quantum systems.

Findings

Codes protect against individual and collective errors

Information recovery uses only collective measurement and control

Applications include extended memory lifetime and loss-tolerant sensing

Abstract

Spin ensembles are promising quantum technological platforms, but their utility relies on the ability to perform quantum error correction (QEC) for the specific decoherence in these systems. Typical QEC for ensembles requires addressing individually resolved qubits, but this is practically challenging in most realistic architectures. Here, we propose QEC schemes for unresolvable spin ensembles. By using degenerate superpositions of excited states, which are fundamentally mixed, we find codes that can protect against both individual and collective errors, including dephasing, decay, and pumping. We show how information recovery can be achieved with only collective measurement and control, and illustrate its applications in extending memory lifetime and loss-tolerant sensing.