Unconditional entanglement interface for quantum networks

TL;DR

This paper demonstrates a method to generate strong continuous-variable entanglement between widely separated optical frequencies by up-converting part of a 1550 nm two-mode squeezed vacuum state to 532 nm, enabling versatile quantum networking.

Contribution

It introduces a novel technique for entangling different optical wavelengths, combining high bandwidth and strong nonclassical correlations for quantum communication.

Findings

Achieved 5.5 dB noise suppression below vacuum in joint quadrature measurements.

Successfully demonstrated entanglement between 1550 nm and 532 nm fields.

The method is versatile and can entangle 1550 nm with any optical wavelength.

Abstract

Entanglement drives nearly all proposed quantum information technologies. By up-converting part of a 1550 nm two-mode squeezed vacuum state to 532 nm, we demonstrate the generation of strong continuous-variable entanglement between widely separated frequencies. Nonclassical correlations were observed in joint quadrature measurements of the 1550 and 532 nm fields, showing a maximum noise suppression 5.5 dB below vacuum. Our versatile technique combines strong nonclassical correlations, large bandwidth, and in principle, the ability to entangle the telecommunication wavelength of 1550 nm with any optical wavelength.