Hannover 2016 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 31: Ultra-cold atoms, ions and BEC I (with A)

Q 31.6: Talk

Wednesday, March 2, 2016, 12:15–12:30, f107

Out-of-equilibrium dynamics of two interacting bosons — •Tim Keller and Thomás Fogarty — Theoretische Physik, Universität des Saarlandes, D-66123 Saarbrücken, Germany

We study the out-of-equilibrium dynamics of two interacting bosons in a one-dimensional harmonic trap after a quench by a centrally located delta-function potential. We are interested in the role of interactions and correlations on this dynamics and have observed many complex phenomena. We make use of an approximate variational calculation called the Lagrange-mesh method to solve the Schrödinger equation numerically. We examine the dynamics by calculating the single particle density and through the time-dependent fidelity (Loschmidt echo) we investigate the irreversibility of the quenched system and its nonlinear dependence on the particles interactions. We discern distinct scattering states created by the quench through a thorough examination of its dynamical properties described by the spectral function. We link the probability distribution of the Loschmidt echo after a long-time evolution to the structure of the spectral function and identify four characteristic distributions which are dependent on quench strength and particle interactions. We lay special focus on the case of a distorted bell-shaped distribution which is caused by a distinct beating in the Loschmidt echo due to the interference of different spectral components. This resonance also has consequences for the particles correlations which mirrors that of the Loschmidt echo.