Optimally Controlled Storage of a Qubit in an Inhomogeneous Spin Ensemble

TL;DR

This paper presents an optimal cavity modulation method to significantly extend qubit storage time in inhomogeneous spin ensembles, overcoming inhomogeneity and cavity decay limitations.

Contribution

The authors develop a Krylov-based control approach and design optimal cavity modulation to enhance qubit lifetime in spin ensembles.

Findings

Achieved an order of magnitude increase in qubit lifetime.

Effectively mitigated inhomogeneous broadening effects.

Enhanced coherence time despite cavity decay.

Abstract

The storage of quantum information in spin-ensembles is limited by practically unavoidable inhomogeneous broadening, and the macroscopic number of spins in such an ensemble makes the design of control solutions to increase the coherence time a challenging task. Together with a concurrently developed Krylov theory that allows us to treat the control problem efficiently, we design optimal cavity modulation for such spin ensembles that achieve an order of magnitude enhancement in qubit lifetime compared to the losses due to inhomogeneity and cavity decay.