Entanglement growth via splitting of a few thermal quanta

TL;DR

This paper explores how splitting a few thermal quanta in nonlinear bosonic systems can generate significant, non-Gaussian entanglement that grows with the number of split quanta, revealing a novel entanglement mechanism.

Contribution

It introduces a new entanglement mechanism driven by thermal quanta splitting in nonlinear systems, beyond Gaussian approximations, with potential experimental realizations.

Findings

Large nonclassicality with >3 dB quadrature squeezing

Entanglement grows with the mean number of split thermal quanta

Passive linear coupling enhances entanglement generation

Abstract

Quanta splitting is an essential generator of Gaussian entanglement, exemplified by Einstein-Podolsky-Rosen states and apparently the most commonly occurring form of entanglement. In general, it results from the strong pumping of a nonlinear process with a highly coherent and low-noise external drive. In contrast, recent experiments involving efficient trilinear processes in trapped ions and superconducting circuits have opened the complementary possibility to test the splitting of a few thermal quanta. Stimulated by such small thermal energy, a strong degenerate trilinear coupling generates large amounts of nonclassicality, detectable by more than 3 dB of distillable quadrature squeezing. Substantial entanglement can be generated via frequent passive linear coupling to a third mode present in parallel with the trilinear coupling. This new form of entanglement, outside any Gaussian approximation, surprisingly grows with the mean number of split thermal quanta; a quality absent from Gaussian entanglement. Using distillable squeezing we shed light on this new entanglement mechanism for nonlinear bosonic systems.