Proposals for realizing a Josephson diode in Atomtronic circuits

TL;DR

This paper proposes and demonstrates a tunable Josephson diode effect in atomtronic circuits using a Bose-Einstein condensate with asymmetric barriers and drive, enabling non-reciprocal quantum transport with high tunability and real-time measurement capabilities.

Contribution

It introduces a novel implementation of the Josephson diode effect in atomtronic circuits, utilizing asymmetric barrier placement and drive for tunable non-reciprocal transport.

Findings

Achieved diode efficiencies up to 15% and 91% with different methods.

Demonstrated real-time, non-destructive measurement of condensate dynamics.

Established a platform for nonreciprocal Josephson transport in neutral-atom systems.

Abstract

The Josephson diode, a non-reciprocal quantum element analogous to the familiar semiconductor p-n junction diode, has been realized in solid-state systems but remains unexplored in tunable atomtronic circuits. In this work, we propose and numerically demonstrate the realization of the Josephson diode effect in an atomtronic circuit consisting of a ring-shaped Bose-Einstein condensate and with optical barriers serving as Josephson junctions. Our implementation of this macroscopic non-reciprocal quantum phenomenon is based on realizing the required inversion symmetry breaking through asymmetric barrier placement and an asymmetric alternating current (AC) drive, enabling position- and drive-tunable diode effects with efficiencies up to 15% and 91%, respectively. While standard time-of-flight absorption imaging can readily observe these effects, we employ cavity optomechanics for in situ, real-time, and non-destructive measurements of the relevant condensate dynamics. Our results establish a highly tunable platform for nonreciprocal Josephson transport, opening avenues for diode-based neutral-atom technologies in future quantum circuits.