title: Memory of the initial conditions in an incompletely chaotic quantum system: universal predictions with application to cold atoms.
abstract: Two zero-range-interacting atoms in a circular, transversely harmonic waveguide are used as a test bench for a quantitative description of the crossover between integrability and chaos in a quantum system with no selection rules. For such systems we show that the expectation value after relaxation of a generic observable is given by a linear interpolation between its initial and thermal expectation values. The variable of this interpolation is universal; it governs this simple law to cover the whole spectrum of the chaotic behavior from integrable regime through the well-developed quantum chaos. The predictions are confirmed for the waveguide system, where the mode occupations and the trapping energy were used as the observables of interest; a variety of the initial states and a full range of the interaction strengths have been tested.
authors.affiliation: School of Chemistry, Tel Aviv University, 69978 Tel Aviv, Israel.
authors.forename: V A
authors.initials: VA
authors.lastname: Yurovsky
authors.forename: M
authors.initials: M
authors.lastname: Olshanii