Inelastic Confinement-Induced Resonances in Low-Dimensional Quantum Systems

We develop the theory of anharmonic confinement-induced resonances (ACIR). These are caused by anharmonic excitation of the transverse motion of the center of mass (COM) of two bound atoms in a waveguide. As the transverse confinement becomes anisotropic, we find that the COM resonant solutions split for a quasi-1D system, in agreement with recent experiments. This is not found in harmonic confinement theories. A new resonance appears for repulsive couplings (a3D > 0) for a quasi-2D system, which is also not seen with harmonic confinement. After inclusion of anharmonic energy corrections within perturbation theory, we find that these ACIR resonances agree extremely well with anomalous 1D and 2D confinement induced resonance positions observed in recent experiments. Multiple even and odd order transverse ACIR resonances are identified in experimental data, including up to N = 4 transverse COM quantum numbers.

Section: Introductionsupporting

confidence: 76%

“…The interesting issue is whether these observed CIR effects can be explained as anharmonic (ACIR) resonances due to center-of-mass excitations of resonant bound states [27][28][29]. This is illustrated in Fig.1, by the two atoms moving together in (a).…”

Section: B Anomalous Cir Experimentsmentioning

confidence: 99%

Confinement-induced resonances in anharmonic waveguides

Peng

Liu

et al. 2011

“…coupling can have a significant impact on an ultracold atomic quantum gas. In [5,6] it was revealed that the particle loss and heating observed in [7] was caused by inelastic confinement-induced resonances (CIR), i. e. resonances due to the c.m.-rel. coupling of a c.m.…”

Section: Introductionmentioning

confidence: 99%

Theory of inelastic confinement-induced resonances due to the coupling of center-of-mass and relative motion

Sala

Sáenz

2016

Self Cite

A detailed study of the anharmonicity-induced resonances caused by the coupling of center-ofmass and relative motion is presented for a system of two ultracold atoms in single-well potentials. As has been confirmed experimentally, these inelastic confinement-induced resonances are of interest, since they can lead to coherent molecule formation, losses, and heating in ultracold atomic gases. A perturbative model is introduced to describe the resonance positions and the coupling strengths. The validity of the model and the behavior of the resonances for different confinement geometries are analyzed in comparison with exact numerical ab initio calculations. While such resonances have so far only been detected for large positive values of the s-wave scattering length, it is found that they are present also for negative s-wave scattering lengths, i. e. for attractive interactions. The possibility to coherently tune the resonances by a variation of the external confinement geometry might pave the way for coherent molecule association where magnetic Feshbach resonances are inaccessible.

“…The introduced methods should be therefore a valuable tools for investigating the exciting physics of Feshbach-interacting atoms in various potentials. In the context of confinement-induced resonances especially the weak coupling between unbound atoms to molecular bound states has recently proven to have a large impact on ultracold-atom experiments [34][35][36]. In this respect the accurate determination of the location and width of the avoided crossings with molecules with center-of-mass excitation at a Feshbach resonance is very important to interpret experimental measurements.…”

Section: Discussionmentioning

confidence: 99%

Two-channel Bose-Hubbard model of atoms at a Feshbach resonance

Schneider

Sáenz

2013

Self Cite

Based on the analytic model of Feshbach resonances in harmonic traps described in Phys. Rev. A 83, 030701 (2011) a Bose-Hubbard model is introduced that provides an accurate description of two atoms in an optical lattice at a Feshbach resonance with only a small number of Bloch bands. The approach circumvents the problem that the eigenenergies in the presence of a delta-like coupling do not converge to the correct energies, if an uncorrelated basis is used. The predictions of the BoseHubbard model are compared to non-perturbative calculations for both the stationary states and the time-dependent wavefunction during an acceleration of the lattice potential. For this purpose, a square-well interaction potential is introduced, which allows for a realistic description of Feshbach resonances within non-perturbative single-channel calculations.