Physicists at the Kastler Brossel Laboratory in Paris have succeeded in coupling a single collective atomic excitation to a nanoscale waveguide for the first time. The entangled state can be stored and subsequently read out with an external laser pulse as a guided single photon. The work could help in the development of the emerging field of waveguide quantum electrodynamics (QED), with applications in quantum networking, quantum nonlinear optics and quantum many-body physics.

The first wired entangled state of atoms using arrays of cold caesium atoms

Researchers have reported the first wired entangled state of atoms using arrays of cold caesium atoms around a nanofibre. They can subsequently read this quantum superposition as a guided single photon. Credit: Kastler Brossel Laboratory

Being able to integrate cold atoms with nanoscale waveguides could be important for making on-chip technologies for a future quantum internet. However, doing this is no easy task.

A team of researchers led by Julien Laurat has now generated and stored a single atomic excitation using an atomic register composed of a chain of laser-cooled caesium atoms tightly trapped along a nanoscale waveguide.

The waveguide has a diameter of just 400 nm, which means that a large fraction of light travels outside it in an evanescent field, focused along a length of 1 cm. This field allows 2000 cold atoms to be trapped around 200 nm from the nanofibre surface.

This stored collective entangled state can be efficiently read out with an external laser pulse, say the researchers.

For more information: Waveguide-coupled single collective excitation of atomic arrays, Neil V. Corzo et al. Nature

For a detailed news story, please email contact@labnaut.com