Abstract: In general, quantum states are very sensitive to coupling to the environment. In many cases this interaction leads to a loss of coherence and a transformation of the quantum mechanical system to classical behavior. However, quantum states can also be stabilized if the environment and the coupling to it are appropriately engineered. This is the basic idea of the research results that I will present in this talk.
In the first part I will show how we extend the concept of coherent perfect absorption (CPA) to nonlinear systems. CPA is the complete extinction of bidirectional incoming radiation by a complex potential in a wave-guiding medium, an effect that relies on the destructive interference of reflected and transmitted waves. We find that the conditions for CPA can be achieved easier than in the linear case since localized absorption in a non-linear medium stabilizes the system. Finally, we experimentally demonstrate CPA for matter waves with an atomic BEC in a one-dimensional optical lattice with an absorptive site where the absorption is introduced by an electron beam.
In the second part I will present our studies of a 3D BEC with a dark kink soliton in the presence of localized dissipation. By numerically solving the 3D Gross-Pitaevskii equation with an imaginary potential we observe the suppression of the snaking instability and extract a threshold value of the dissipation strength for the stabilization of the dark soliton. Above the stabilization threshold, we observe the attractor dynamics towards the dark soliton when initially starting from a gray soliton. We find that for all initial conditions the dark soliton is the unique steady-state of the system – even when starting from the BEC ground state.
Host: Ian Spielman