Experimental realization of Josephson junctions for an Atom SQUID

TL;DR

This paper demonstrates the creation and observation of Josephson junctions in a Bose-Einstein condensate, forming an atom-based SQUID device with potential applications in rotation sensing.

Contribution

It reports the first experimental realization of Josephson junctions in a BEC and their integration into a toroidal trap using painted potentials, enabling scalable atom circuit geometries.

Findings

Observed Josephson effects in BEC junctions

Measured critical current consistent with Josephson equations

Demonstrated potential for rotation sensing with atom SQUIDs

Abstract

We report the creation of a pair of Josephson junctions on a toroidal dilute gas Bose-Einstein condensate (BEC), a configuration that is the cold atom analog of the well-known dc superconducting quantum interference device (SQUID). We observe Josephson effects, measure the critical current of the junctions, and find dynamic behavior that is in good agreement with the simple Josephson equations for a tunnel junction with the ideal sinusoidal current-phase relation expected for the parameters of the experiment. The junctions and toroidal trap are created with the painted potential, a time-averaged optical dipole potential technique which will allow scaling to more complex BEC circuit geometries than the single atom-SQUID case reported here. Since rotation plays the same role in the atom SQUID as magnetic field does in the dc SQUID magnetometer, the device has potential as a compact rotation sensor.