Quasiprobability fluctuation theorem behind the spread of quantum information

TL;DR

This paper uncovers a quantum fluctuation theorem based on quasiprobabilities that explains how quantum information spreads and dissipates, supported by experimental verification on a quantum computer.

Contribution

It introduces a novel quasiprobability-based fluctuation theorem that extends the understanding of quantum information dynamics beyond classical limits.

Findings

The fluctuation theorem predicts quantum information dissipation statistics.

Experimental verification was successfully performed on IBM quantum hardware.

The quasiprobability approach captures quantum effects in information spreading.

Abstract

Information spreads in time. For example, correlations dissipate when the correlated system locally couples to a third party, such as the environment. This simple but important fact forms the known quantum data-processing inequality. Here we theoretically uncover the quantum fluctuation theorem behind the quantum informational inequality. The fluctuation theorem quantitatively predicts the statistics of the underlying stochastic quantum process. To fully capture the quantum nature, the fluctuation theorem established here is extended to the quasiprobability regime. We also experimentally apply an interference-based method to measure the amplitudes composing the quasiprobability and verify our established fluctuation theorem by the IBM quantum computer.