Photon-induced self-trapping and entanglement of a bosonic Josephson junction inside an optical resonator

Abstract

We study the influence of photons on the dynamics and the ground state of the atoms in a Bosonic Josephson junction inside an optical resonator. The system is engineered in such a way that the atomic tunneling can be tuned by changing the number of photons in the cavity. In this setup the cavity photons are a new means of control, which can be utilized both in inducing selftrapping solutions and in driving the crossover of the ground state from an atomic coherent state to a Schrödinger's cat state. This is achieved, for suitable setup configurations, with interatomic interactions weaker than those required in the absence of cavity. This is corroborated by the study of the entanglement entropy. In the presence of a laser, this quantum indicator attains its maximum value (which marks the formation of the cat-like state and, at a semiclassical level, the onset of self-trapping) for attractions smaller than those of the bare junction.

Controlling dynamical entanglement in a Josephson tunneling junction

“…Here we have included a simultaneous change of the interaction parameter to different values in the wells. Such a change can be realized either by modifying the trapping potential [18,19,25] or by coupling photons directly to the atoms in the junction [29]. The evolution after the raise of the barrier reads…”