Entangling two distant nanocavities via a waveguide

TL;DR

This paper demonstrates how to generate and control continuous variable entanglement between two distant nanocavities mediated by a waveguide, revealing conditions for stable entanglement and effects of coupling strength.

Contribution

It provides an exact dynamical analysis of entanglement generation in nanocavities coupled via a waveguide, highlighting the influence of coupling strength and cavity frequencies.

Findings

Stable and pure entangled states are achievable with weak cavity-waveguide coupling.

Strong coupling causes entanglement sudden death and birth phenomena.

Adjusting cavity frequencies outside the waveguide band can optimize entanglement.

Abstract

In this paper, we investigate the generation of continuous variable entanglement between two spatially-separate nanocavities mediated by a coupled resonator optical waveguide in photonic crystals. By solving the exact dynamics of the cavity system coupled to the waveguide, the entanglement and purity of the two-mode cavity state are discussed in detail for the initially separated squeezing inputs. It is found that the stable and pure entangled state of the two distant nanocavities can be achieved with the requirement of only a weak cavity-waveguide coupling when the cavities are resonant with the band center of the waveguide. The strong couplings between the cavities and the waveguide lead to the entanglement sudden death and sudden birth. When the frequencies of the cavities lie outside the band of the waveguide, the waveguide-induced cross frequency shift between the cavities can optimize the achievable entanglement. It is also shown that the entanglement can be easily manipulated through the changes of the cavity frequencies within the waveguide band.