Observation of time-invariant coherence in a room temperature quantum simulator

TL;DR

This paper reports the experimental observation of time-invariant quantum coherence at room temperature in nuclear magnetic resonance setups, demonstrating resilience of quantum effects in complex systems without active control.

Contribution

First experimental demonstration of indefinite coherence preservation in a room temperature quantum simulator using NMR techniques.

Findings

Quantum coherence remains invariant over time in the studied systems.

The phenomenon occurs without system control and is independent of coherence measures.

Reveals a new relationship between coherence and correlations in quantum systems.

Abstract

The ability to live in coherent superpositions is a signature trait of quantum systems and constitutes an irreplaceable resource for quantum-enhanced technologies. However, decoherence effects usually destroy quantum superpositions. It has been recently predicted that, in a composite quantum system exposed to dephasing noise, quantum coherence in a transversal reference basis can stay protected for indefinite time. This can occur for a class of quantum states independently of the measure used to quantify coherence, and requires no control on the system during the dynamics. Here, such an invariant coherence phenomenon is observed experimentally in two different setups based on nuclear magnetic resonance at room temperature, realising an effective quantum simulator of two- and four-qubit spin systems. Our study further reveals a novel interplay between coherence and various forms of correlations, and highlights the natural resilience of quantum effects in complex systems.