Clock transition by continuous dynamical decoupling of a three-level system

TL;DR

This paper introduces a continuous dynamical decoupling method for three-level systems that creates a robust qubit by tuning clock transitions, significantly enhancing coherence times against environmental and drive noise.

Contribution

It proposes a novel scheme for constructing robust qubits in three-level systems using clock transition adjustments to suppress noise effects, demonstrated with NV-centre spin states.

Findings

Achieved two orders of magnitude increase in coherence time with drive noise elimination.

Tuned clock transition to suppress second-order environmental noise effects.

Simulations predict further coherence time improvements beyond current results.

Abstract

We present a novel continuous dynamical decoupling scheme for the construction of a robust qubit in a three-level system. By means of a clock transition adjustment, we first show how robustness to environmental noise is achieved, while eliminating drive-noise, to first-order. We demonstrate this scheme with the spin sub-levels of the NV-centre's electronic ground state. By applying drive fields with moderate Rabi frequencies, the drive noise is eliminated and an improvement of 2 orders of magnitude in the coherence time is obtained compared to the pure dephasing time. We then show how the clock transition adjustment can be tuned to eliminate also the second-order effect of the environmental noise with moderate drive fields. A further improvement of more than 1 order of magnitude in the coherence time is expected and confirmed by simulations. Hence, our scheme prolongs the coherence time towards the lifetime-limit using a relatively simple experimental setup.