Engineering Ponderomotive Potential for Realizing $\pi$ and $\pi/2$ Bosonic Josephson Junctions

TL;DR

This paper explores how high-frequency electromagnetic fields can engineer the ponderomotive potential in bosonic Josephson junctions, enabling stabilization of $ ext{pi}$ and $ ext{pi/2}$ phase modes through dynamical control.

Contribution

It introduces a method to control phase modes in bosonic Josephson junctions using ponderomotive potentials, including stabilization of $ ext{pi}$ and $ ext{pi/2}$ modes beyond traditional approximations.

Findings

Ponderomotive drive induces Kapitza pendulum effect stabilizing $ ext{pi}$-phase mode.

Transition from self-trapping to $ ext{pi}$-oscillations depends on parameters.

Momentum-shortening effect enables $ ext{pi/2}$-phase mode stabilization under certain conditions.

Abstract

We study the ponderomotive potential of a bosonic Josephson junction periodically modulated by a high-frequency electromagnetic field. Within the small population difference approximation, the ponderomotive drive induces the well-known Kapitza pendulum effect, stabilizing a $\pi$-phase mode. We discuss the parameter dependence of the dynamical transition from macroscopic quantum self-trapping to $\pi$-Josephson oscillations. Furthermore, we examine the situation where the small population difference approximation fails. In this case, an essential momentum-shortening effect emerges, leading to a stabilized $\pi/2$-phase mode under certain conditions. By mapping this to a classical pendulum scenario, we highlight the uniqueness and limitations of the $\pi/2$-phase mode in bosonic Josephson junctions.