Determination of maximal Gaussian entanglement achievable by feedback-controlled dynamics

TL;DR

This paper establishes an upper limit for steady-state Gaussian entanglement achievable through feedback control in bosonic systems, identifying optimal strategies and comparing local versus nonlocal feedback schemes.

Contribution

It introduces a general upper bound for entanglement via feedback in bosonic systems and finds optimal feedback strategies to maximize entanglement, including local operation constraints.

Findings

Derived a universal upper bound for steady-state entanglement.

Identified optimal feedback strategies for parametric interactions.

Compared local and nonlocal feedback schemes, highlighting performance differences.

Abstract

We determine a general upper bound for the steady-state entanglement achievable by continuous feedback for systems of any number of bosonic degrees of freedom. We apply such a bound to the specific case of parametric interactions - the most common practical way to generate entanglement in quantum optics - and single out optimal feedback strategies that achieve the maximal entanglement. We also consider the case of feedback schemes entirely restricted to local operations and compare their performance to the optimal, generally nonlocal, schemes.