Converting Nonclassicality into Entanglement

TL;DR

This paper introduces a comprehensive framework based on superposition to convert various forms of nonclassicality into entanglement, unifying and extending previous results across discrete and continuous quantum systems.

Contribution

It provides a general superposition-based framework that captures known and uncovers new theorems for converting nonclassicality into entanglement in diverse quantum settings.

Findings

Unifies conversion of nonclassicality to entanglement across different quantum resources.

Derives new entanglement convertibility theorems for discrete and continuous systems.

Links resource theories of coherence, spin, and optical states through a common framework.

Abstract

Quantum mechanics exhibits a wide range of nonclassical features, of which entanglement in multipartite systems takes a central place. In several specific settings, it is well known that nonclassicality (e.g., squeezing, spin squeezing, coherence) can be converted into entanglement. In this work, we present a general framework, based on superposition, for structurally connecting and converting nonclassicality to entanglement. In addition to capturing the previously known results, this framework also allows us to uncover new entanglement convertibility theorems in two broad scenarios, one which is discrete and one which is continuous. In the discrete setting, the classical states can be any finite linearly independent set. For the continuous setting, the pertinent classical states are 'symmetric coherent states,' connected with symmetric representations of the group SU(K). These results generalize and link convertibility properties from the resource theory of coherence, spin coherent states, and optical coherent states, while also revealing important connections between local and nonlocal pictures of nonclassicality.