Observation of anomalous decoherence effect in a quantum bath at room temperature

TL;DR

This paper reports the experimental observation of an anomalous decoherence effect in a quantum bath at room temperature, where certain transitions exhibit longer coherence times despite stronger coupling, challenging conventional expectations.

Contribution

It provides the first experimental validation of the anomalous decoherence effect in a quantum bath at room temperature, demonstrating control over nuclear spin interactions.

Findings

Double-transition coherence time exceeds single-transition under dynamical decoupling.

Experimental results align with theoretical predictions.

Control over nuclear spins enhances quantum information processing.

Abstract

Decoherence of quantum objects is critical to modern quantum sciences and technologies. It is generally believed that stronger noises cause faster decoherence. Strikingly, recent theoretical research discovers the opposite case for spins in quantum baths. Here we report experimental observation of the anomalous decoherence effect for the electron spin-1 of a nitrogen-vacancy centre in high-purity diamond at room temperature. We demonstrate that under dynamical decoupling, the double-transition can have longer coherence time than the single-transition, even though the former couples to the nuclear spin bath as twice strongly as the latter does. The excellent agreement between the experimental and the theoretical results confirms the controllability of the weakly coupled nuclear spins in the bath, which is useful in quantum information processing and quantum metrology.