A bosonic Josephson junction controlled by a single trapped ion

TL;DR

This paper proposes a theoretical method to control a bosonic Josephson junction using a single trapped ion, enabling state-dependent tunneling and entanglement generation between atomic and ionic systems.

Contribution

It introduces a novel scheme for controlling a bosonic Josephson junction via a single ion's internal state, facilitating high-precision interaction measurements and entanglement.

Findings

Coupling rates up to hundreds of Hz between wells.

State-dependent control of tunneling and self-trapping regimes.

Feasibility of generating large-scale ion-atomic entanglement.

Abstract

We theoretically investigate the properties of a double-well bosonic Josephson junction coupled to a single trapped ion. We find that the coupling between the wells can be controlled by the internal state of the ion, which can be used for studying mesoscopic entanglement between the two systems and to measure their interaction with high precision. As a particular example we consider a single $^{87}$Rb atom and a small Bose-Einstein condensate controlled by a single $^{171}$Yb$^+$ ion. We calculate inter-well coupling rates reaching hundreds of Hz, while the state dependence amounts to tens of Hz for plausible values of the currently unknown s-wave scattering length between the atom and the ion. The analysis shows that it is possible to induce either the self-trapping or the tunneling regime, depending on the internal state of the ion. This enables the generation of large scale ion-atomic wavepacket entanglement within current technology.