Protecting Quantum Information via Destructive Interference of Correlated Noise

Decoherence remains a major challenge for quantum technologies. Several important strategies, such as decoherence-free spaces, clock transitions, dynamical decoupling, and composite pulses, reduce the effect of noise, lowering decoherence and control error rates. Each strategy takes advantage of a certain “resource” to protect quantum information.

In this work, we propose and experimentally demonstrate a protection strategy that leverages a new kind of resource – the cross-correlation of two noise sources, e.g. control fields. Such cross-correlations exist when the control fields are generated from the same source or pass through the same transmission line.

As an example, we modify the continuous concatenated dynamical decoupling control scheme. As we show, introducing a frequency shift to one of the control fields, which is proportional to the degree of cross-correlation, results in destructive interference of the cross-correlated noise. Our scheme results in a tenfold increase in the coherence time of a single NV center in diamond, and outperforms the widely used XY8 sequence. Furthermore, we demonstrate the magnetometry of GHz signals with record sensitivity and robust qubit operations.

In light of recent characterizations of noise cross-correlations in quantum systems, our contribution opens a new avenue in the field of noise protection for quantum technologies.