Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

QUANTUM GASES

An ultracold junction

Science 369, 84–91 (2020)

Two superconductors weakly coupled through an insulating potential barrier form a Josephson junction. Electrons on each side of the barrier can be described by a macroscopic wavefunction, and the phase difference between them leads to a current flowing across the junction — known as the Josephson effect. Now, Woo Jin Kwon and co-workers, as well as Niclas Luick and co-workers, have observed the same effect in charge-neutral systems made of ultracold 6Li atoms.

Like electrons, the atoms in these experiments are fermions, and can form pairs and condense in the same quantum state at sufficiently low temperature. An optical barrier inserted in the centre turned the system into a junction. A current across the barrier was induced either by imposing an initial phase difference between the two parts or by directly moving the optical barrier with respect to the atoms. Both groups observed a sinusoidal current–phase relation — a distinctive feature of the Josephson effect — by monitoring the subsequent evolution of the atom number and of the phase of the wavefunction.

Author information

Affiliations

Authors

Corresponding author

Correspondence to Yun Li.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Li, Y. An ultracold junction. Nat. Phys. 16, 819 (2020). https://doi.org/10.1038/s41567-020-1015-5

Download citation

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing