Resource efficient certification of system environment entanglement solely from reduced system dynamics

TL;DR

This paper introduces a resource-efficient method to certify system-environment entanglement using only reduced system dynamics, applicable to non-autonomous pure dephasing scenarios, validated experimentally on a quantum processor.

Contribution

It provides a novel approach to certify entanglement solely from system dynamics, relaxing the need for full-time data and applicable to general non-autonomous scenarios.

Findings

Successfully certified entanglement on a trapped-ion quantum processor.

Method works without full-time dynamics, reducing experimental resources.

Potential application in certifying gravitationally induced entanglement.

Abstract

Certifying nonclassical correlations typically requires access to all subsystems, presenting a major challenge in open quantum systems coupled to inaccessible environments. Recent works have shown that, in autonomous pure dephasing scenarios, quantum discord with the environment can be certified from system-only dynamics via the Hamiltonian ensemble formulation. However, this approach leaves open whether stronger correlations, such as entanglement, can be certified. Moreover, its reliance on Fourier analysis requires full-time dynamics, which is experimentally resource-intensive and provides limited information about when such correlations are established during evolution. In this work, we present a method that enables the certification of system-environment quantum entanglement solely from the reduced dynamics of the system. The method is based on the theory of mixed-unitary channels and applies to general non-autonomous pure dephasing scenarios. Crucially, it relaxes the need for full-time dynamics, offering a resource-efficient approach that also reveals the precise timing of entanglement generation. We experimentally validate this method on a Quantinuum trapped-ion quantum processor with a controlled-dephasing model. Finally, we highlight its potential as a tool for certifying gravitationally induced entanglement.