Non-linear systems give rise to a rich array of phenomena including chaos, turbulence, solitons, and dynamical instabilities. The great degree of experimental control over Bose Einstein condensates makes them a unique tool to study these processes. In this seminar we present experimental results utilising a dual-species 85Rb/87Rb BEC system where the precise manipulation of non-linear interactions is achieved through a Feshbach resonance.

Initially we investigate the behaviour of single component BECs and the formation of soliton trains in an optical waveguide. Using the nonpolynomial Schrodinger equation, it is shown that the formation of soliton trains can be understood as a manifestation of a modulational instability (MI). With the use of a non-destructive imaging system we subsequently make the first real time observation of MI in a BEC.The addition of a second component to the system allows a wider variety of coupled non-linear phenomena to be investigated. Crucial to accessing applicable regimes is the reliable preparation of mixed groundstates in different configurations.

We present a detailed experimental study of phase separated groundstates for the 85Rb/87Rb BEC system and show that sensitively tuning the energy scales of the system allows a wide variety of immiscible groundstates to be created.”