arXiv subjects

Igor Lesanovsky

Publications and source records attributed to Igor Lesanovsky.

222 records · Page 13Linked to original sources

arXiv2006

Spontaneous emergence of angular momentum Josephson oscillations in coupled annular Bose-Einstein condensates

We investigate the nonlinear dynamics of two coupled annular Bose-Einstein condensates (BECs). For certain values of the coupling strength the nonrotating ground state is unstable with respect to fluctuations in the higher angular momentum modes. The two branched Bogoliubov spectrum exhibits distinct regions of instability enabling one to selectively occupy certain angular momentum modes. For sufficiently long evolution times angular momentum Josephson oscillations spontaneously appear, breaking the initial chiral symmetry of the BECs.

quant-ph↗

arXiv2006

Negative Energy Resonances of Bosons in a Magnetic Quadrupole Trap

We investigate resonances of spin 1 bosons in a three-dimensional magnetic quadrupole field. Complementary to the well-known positive energy resonances it is shown that there exist short-lived, i.e. broad, negative energy resonances. The latter are characterized by an atomic spin that is aligned antiparallel to the local magnetic field direction. In contrast to the positive energy resonances the lifetimes of the negative energy resonances decreases with increasing total magnetic quantum number. We derive a mapping of the two branches of the spectrum.

physics.atom-ph↗

arXiv2006

Controlling ultracold Rydberg atoms in the quantum regime

We discuss the properties of Rydberg atoms in a magnetic Ioffe-Pritchard trap being commonly used in ultracold atomic physics experiments. The Hamiltonian is derived and it is demonstrated how tight traps alter the coupling of the atom to the magnetic field. We solve the underlying Schroedinger equation of the system within a given n-manifold and show that for a sufficiently large Ioffe field strength the 2n^2-dimensional system of coupled Schroedinger equations decays into several decoupled multicomponent equations governing the center of mass motion. An analysis of the fully quantized center of mass and electronic states is undertaken. In particular, we discuss the situation of tight center of mass confinement outlining the procedure to generate a low-dimensional ultracold Rydberg gas.

physics.atom-ph↗

arXiv2004

Spectral Properties and Lifetimes of Neutral Spin-1/2-Fermions in a Magnetic Guide

We investigate the resonant motion of neutral spin-1/2-fermions in a magnetic guide. A wealth of unitary and anti-unitary symmetries is revealed in particular giving rise to a two-fold degeneracy of the energy levels. To compute the energies and decay widths of a large number of resonances the complex scaling method is employed. We discuss the dependence of the lifetimes on the angular momentum of the resonance states. In this context the existence of so-called quasi-bound states is shown. In order to approximately calculate the resonance energies of such states a radial Schrödinger equation is derived which improves the well-known adiabatic approximation. The effects of an additionally applied homogeneous Ioffe field on the resonance energies and decay widths are also considered. The results are applied to the case of the $^6\text{Li}$ atom in the $F=1/2$ hyperfine ground state.

physics.atom-ph↗

arXiv2004

Rydberg Atoms in a Magnetic Guide

We investigate electronically excited atoms in a magnetic guide. It turns out that the Hamiltonian describing this system possesses a wealth of both unitary as well as antiunitary symmetries that constitute an uncommon extensive symmetry group. One consequence is the two-fold degeneracy of any energy level. The spectral properties are investigated for a wide range of field gradients and the spatial distributions of the spin polarization are analyzed. Wave lengths, oscillator strengths and selection rules are provided for the corresponding electromagnetic transitions. The effects due to an additional homogeneous bias field constituting a Ioffe-Pritchard trap are explored equally.

physics.atom-ph↗

arXiv2004

Electronic Structure of Atoms in Magnetic Quadrupole Traps

We investigate the electronic structure and properties of atoms exposed to a magnetic quadrupole field. The spin-spatial as well as generalized time reversal symmetries are established and shown to lead to a two-fold degeneracy of the electronic states in the presence of the field. Low-lying as well as highly excited Rydberg states are computed and analyzed for a broad regime of field gradients. The delicate interplay between the Coulomb and various magnetic interactions leads to complex patterns of the spatial spin polarization of individual excited states. Electromagnetic transitions in the quadrupole field are studied in detail thereby providing the selection rules and in particular the transition wavelengths and corresponding dipole strengths. The peculiar property that the quadrupole magnetic field induces permanent electric dipole moments of the atoms is derived and discussed.

physics.atom-ph↗