Contributor info: Prof. Daniel Burgarth

Daniel Burgarth, Paolo Facchi, Martin Fraas, Robin Hillier

SciPost Phys. 11, 027 (2021) · published 10 August 2021 | Toggle abstract · pdf

Dynamical decoupling is the leading technique to remove unwanted interactions in a vast range of quantum systems through fast rotations. But what determines the time-scale of such rotations in order to achieve good decoupling? By providing an explicit counterexample of a qubit coupled to a charged particle and magnetic monopole, we show that such time-scales cannot be decided by the decay profile induced by the noise: even though the system shows a quadratic decay (a Zeno region revealing non-Markovian noise), it cannot be decoupled by periodic spin echo pulses, no matter how fast the rotations.