Bang-Bang control of a qubit coupled to a quantum critical spin bath

TL;DR

This paper investigates how pulsed control influences qubit decoherence when coupled to a quantum critical spin bath, revealing enhanced control effectiveness near criticality through analytical and numerical methods.

Contribution

It introduces a detailed analysis of pulsed control effects on qubits in critical environments, comparing two coupling models to demonstrate consistent results.

Findings

Decoherence is faster near quantum critical points.

Pulsed control is more effective in critical environments.

Results are consistent across different coupling models.

Abstract

We analytically and numerically study the effects of pulsed control on the decoherence of a qubit coupled to a quantum spin bath. When the environment is critical, decoherence is faster and we show that the control is relatively more effective. Two coupling models are investigated, namely a qubit coupled to a bath via a single link and a spin star model, yielding results that are similar and consistent.