Anomalous decoherence effect in a quantum bath

TL;DR

This paper predicts an anomalous decoherence effect in a quantum bath where multi-transitions of a nitrogen-vacancy center can have longer coherence times than single-transitions, contrary to common expectations.

Contribution

It introduces the concept of anomalous decoherence in a quantum bath and explains how bath manipulation can lead to longer coherence times for multi-transitions.

Findings

Multi-transitions can have longer coherence times despite stronger noise.

Bath manipulation via spin flips affects decoherence behavior.

Contradicts the common belief that stronger noise always causes faster decoherence.

Abstract

Decoherence of quantum objects in noisy environments is important in quantum sciences and technologies. It is generally believed that different processes coupled to the same noise source should have similar decoherence behaviors and stronger noises would cause faster decoherence. Here we show that in a quantum bath, the case can be the opposite. In particular, we predict that the multi-transition of a nitrogen-vacancy center spin-1 in diamond can have longer coherence time than the single-transitions, even though the former suffers twice stronger noises from the nuclear spin bath than the latter. This anomalous decoherence effect is due to manipulation of the bath evolution via flips of the center spin.