Decoherence Mitigation by Embedding a Logical Qubit in a Qudit

TL;DR

Embedding a logical qubit within a qudit manifold can significantly extend quantum information lifetime by providing additional pathways for coherent evolution, thus mitigating decoherence effects in quantum systems.

Contribution

This paper introduces a novel scheme to embed a logical qubit in a qudit to enhance quantum information preservation, demonstrating extended lifetimes compared to traditional qubits.

Findings

Logical qubit embedded in a qudit exhibits longer coherence times.

Separation of sublevels improves quantum information retention.

Additional pathways within the qudit manifold enable reversible evolution.

Abstract

Quantum information stored in a qubit is rapidly lost to the environment. The realization of robust qubits is one of the most important challenges in quantum computing. Herein we propose to embed a logical qubit within the manifold of a qudit as a scheme to preserve quantum information over extended periods of time. Under identical conditions (e.g. decoherence channels) the submanifold of the logical qubit exhibits extended lifetimes compared to a pure two-level system (qubit). The retention of quantum information further improves with separation between the sublevels of the logical qubit. Lifetime enhancement can be understood in terms of entropy production of the encoding and non-encoding subspaces during evolution under a quantum map for a $d$-level system. The additional pathways for coherent evolution through intermediate sublevels within a $d$-level manifold provide an information-preserving mechanism: reversible alternative channels to the irreversible loss of information to the environment characteristic of open quantum systems.