Nonlinearity as a resource for nonclassicality in anharmonic systems

TL;DR

This paper demonstrates that anharmonicity in quantum oscillator potentials correlates with nonclassical features like Wigner negativity and entanglement potential, suggesting nonlinearity as a resource for quantum technology development.

Contribution

It establishes a monotonic relationship between potential anharmonicity and nonclassicality measures, providing insights for designing quantum oscillators with enhanced nonclassical features.

Findings

Nonlinearity correlates with Wigner negativity in ground states.

Entanglement potential increases with anharmonicity.

Results confirmed for sixth-order potentials.

Abstract

Nonclassicality is a key ingredient for quantum enhanced technologies and experiments involving macro- scopic quantum coherence. Considering various exactly-solvable quantum-oscillator systems, we address the role played by the anharmonicity of their potential in the establishment of nonclassical features. Specifically, we show that a monotonic relation exists between the the entropic nonlinearity of the considered potentials and their ground state nonclassicality, as quantified by the negativity of the Wigner function. In addition, in order to clarify the role of squeezing--which is not captured by the negativity of the Wigner function--we focus on the Glauber-Sudarshan P-function and address the nonclassicality/nonlinearity relation using the entanglement potential. Finally, we consider the case of a generic sixth-order potential confirming the idea that nonlinearity is a resource for the generation of nonclassicality and may serve as a guideline for the engineering of quantum oscillators.