# Berlin 2014 – wissenschaftliches Programm

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# Q: Fachverband Quantenoptik und Photonik

## Q 52: Ultracold atoms, ions and BEC V (with A)

### Q 52.7: Vortrag

### Donnerstag, 20. März 2014, 18:00–18:15, BEBEL SR140/142

**Broken Integrability Trace on Stationary Correlation Properties** — •Ioannis Brouzos^{1}, Angela Foerster^{2}, and Tommaso Calarco^{1} — ^{1}Institut für Quanteninformationsverarbeitung, Universität Ulm — ^{2}Instituto de Fisica da UFRGS, Av. Bento Gonccalves

We show that the breaking of integrability in the fundamental one-dimensional model of bosons with contact interactions leaves its trace on the stationary correlation properties of the system. We calculate energies and correlation functions of the integrable Lieb-Liniger case where all pairs of atoms interact with the same strength, comparing the Bethe with a corresponding Jastrow ansatz which are the basic constructions of correlated wave-functions in many-body quantum physics. Then we examine the non-integrable case of different interaction strengths between each pair of atoms by means of a modified (and variationally optimized) Jastrow ansatz which we propose as a very good approximation for this case. We show that properties of the integrable state are more stable (persist if the integrability is not extremely broken) close to the infinitely strong interacting Tonks-Girardeau regime than for week interactions. All energies and correlation functions are given in terms of explicit analytical expressions which the Jastrow ansatz makes possible. We finally compare the correlations of the integrable and non-integrable case and show that appart from symmetry breaking the behavior changes dramatically, with additional and more pronounced maxima and minima (interference peaks) appearing.