From Rabi oscillations to quantum instability

Vicky Howse, Raymond J. Spiteri

Abstract Faraday or parametric instability has been observed in various contexts in Bose–Einstein condensates. In Rabi-coupled condensates, the instability can arise without explicit modulation of external parameters. We study the dynamics of an interface in a two-component immiscible condensate near the miscible-immiscible threshold, with Rabi coupling between components. We show that a small initial perturbation leads to oscillations that grow in amplitude with increasing Rabi frequency until the interface produces droplet-like structures. We find that the interface oscillations are driven by parametric resonance with density oscillations in the bulk. This parametric instability of the interface provides a link to the walking droplet pilot wave system, which is governed by the Faraday instability. Because walking droplets simulate fundamentally quantum behaviors, and ‘vortex molecules,’ which are hosted by a Rabi-coupled condensate, simulate quark confinement, this observation suggests a mechanism-level connection between these systems and provides a possible bridge between distinct analog models of fundamental particles.

F. Suekane

R. Graham, Michael Höhnerbach

Monika Nath, Rohit Mukherjee, Nitu Borgohain

This article explores the modulation instability of a continuous or quasi-continuous weak probe pulse in a three-level asymmetric double quantum wells under an electromagnetically induced transparency regime, controlled by a strong laser beam. The dynamics of modulation instability reveals that the instability gain as well as its bandwidth is greatly influenced by control field Rabi frequency. The probe pulse is found to be almost stable against modulation instability for higher values of control field Rabi frequency. The results of this investigation may potentially apply for oscillation free generation of supercontinuum in quantum well nanostructures.

Pavel V. Paulau, Natalia A. Loiko

This study investigates a structure including two such films irradiated from one side. Such a bilayer system can be considered as the basic element of a multilayer structure determining the main features of the all structure on the one hand and as individual element transforming the light on the other hand. Superradiation of the film both in the direction of incident beam and in the back direction provides the delay feedback between separate films. This study reveals two mechanisms of Hopf instabilities in the described thin-film system. The first mechanism is connected with the existence of multistable steady-state characteristic due to the superradiance and local field correction, while the second is relevant to the excitement of Rabi oscillations. Arising pulsations are sustained by the delay feedback existing between two films. The threshold value of the feedback delay can be minimized by the proper choice of parameters and even reduced to zero in the case of Rabi oscillations excitement.

Anne Boutet de Monvel, Lech Zieliński