We report on a theoretical and experimental study of state-selective differential single-electron transfer cross sections between ${\mathrm{Na}}^{+}$ ions and $\mathrm{Rb}(5s,5p)$ atoms at collision energies of 2, 5, and 7 keV. A two-center multichannel semiclassical impact parameter close-coupling method with straight-line trajectories was used to obtain single-electron capture amplitudes. By combining with the eikonal approximation, we calculated the angular differential cross sections. These results are compared to the experimental data obtained with Rb targets cooled in a magnetic optical trap. It is shown that there is generally a good agreement between the present calculations and the experiments. In spite of the higher resolution offered from the cold target, the rapid oscillations in the differential cross sections are not resolved by the experiments.We report on a theoretical and experimental study of state-selective differential single-electron transfer cross sections between ${\mathrm{Na}}^{+}$ ions and $\mathrm{Rb}(5s,5p)$ atoms at collision energies of 2, 5, and 7 keV. A two-center multichannel semiclassical impact parameter close-coupling method with straight-line trajectories was used to obtain single-electron capture amplitudes. By combining with the eikonal approximation, we calculated the angular differential cross sections. These results are compared to the experimental data obtained with Rb targets cooled in a magnetic optical trap. It is shown that there is generally a good agreement between the present calculations and the experiments. In spite of the higher resolution offered from the cold target, the rapid oscillations in the differential cross sections are not resolved by the experiments.

Physical Review AOct 1, 200231 citations

Collision-Induced Coherences in Optical Physics

G. S. Agarwal

Advances in atomic, molecular, and optical physicsJan 1, 199110 citations

Characterization and control of ultracold collisions

Stephen D. Gensemer

A series of experiments investigating ultracold collision dynamics are performed. In particular, I investigate a number of new methods by which lasers may increase or decrease inelastic collision rates. The experiments are performed in a Rb magneto-optical trap (MOT). In addition, the dynamics of excited-ground ultracold collisions are investigated in the temporal domain. Semiclassical simulations of the collision processes are performed to provide a simple, intuitive model for ultracold collisions in the presence of laser light. ^A series of experiments investigating ultracold collision dynamics are performed. In particular, I investigate a number of new methods by which lasers may increase or decrease inelastic collision rates. The experiments are performed in a Rb magneto-optical trap (MOT). In addition, the dynamics of excited-ground ultracold collisions are investigated in the temporal domain. Semiclassical simulations of the collision processes are performed to provide a simple, intuitive model for ultracold collisions in the presence of laser light. ^

Aug 1, 20001 citation

Nonlinear semiclassical dynamics of the unbalanced, open Dicke model

Kevin C. Stitely, Andrus Giraldo, Bernd Krauskopf +1 more

In recent years there have been significant advances in the study of many-body interactions between atoms and light confined to optical cavities.One model that has received widespread attention of late is the Dicke model, which under certain conditions exhibits a quantum phase transition to a state in which the atoms collectively emit light into the cavity mode, known as superradiance.We consider a generalization of this model that features independently controllable strengths of the corotating and counter-rotating terms of the interaction Hamiltonian.We study this system in the semiclassical (mean field) limit, i.e., neglecting the role of quantum fluctuations.Under this approximation, the model is described by a set of nonlinear differential equations, which determine the system's semiclassical evolution.By taking a dynamical systems approach, we perform a comprehensive analysis of these equations to reveal an abundance of complex dynamics.Examples of the phenomena that we observe are the emergence of superradiant oscillations arising due to Hopf bifurcations, and the appearance of a pair of chaotic attractors arising from period-doubling cascades, followed by their collision to form a single, larger chaotic attractor via a sequence of infinitely many homoclinic bifurcations.Moreover, we find that a flip of the collective spin can result in the sudden emergence of chaotic dynamics.Overall, we provide a comprehensive road map of the possible dynamics that arise in the unbalanced, open Dicke model in the form of a phase diagram in the plane of the two interaction strengths.Hence, we lay out the foundations to make further advances in the study of the fingerprint of semiclassical chaos when considering the master equation of the unbalanced Dicke model, thus, providing the possibility of studying a manifestation of quantum chaos in a specific, experimentally realizable system.In recent years there have been significant advances in the study of many-body interactions between atoms and light confined to optical cavities.One model that has received widespread attention of late is the Dicke model, which under certain conditions exhibits a quantum phase transition to a state in which the atoms collectively emit light into the cavity mode, known as superradiance.We consider a generalization of this model that features independently controllable strengths of the corotating and counter-rotating terms of the interaction Hamiltonian.We study this system in the semiclassical (mean field) limit, i.e., neglecting the role of quantum fluctuations.Under this approximation, the model is described by a set of nonlinear differential equations, which determine the system's semiclassical evolution.By taking a dynamical systems approach, we perform a comprehensive analysis of these equations to reveal an abundance of complex dynamics.Examples of the phenomena that we observe are the emergence of superradiant oscillations arising due to Hopf bifurcations, and the appearance of a pair of chaotic attractors arising from period-doubling cascades, followed by their collision to form a single, larger chaotic attractor via a sequence of infinitely many homoclinic bifurcations.Moreover, we find that a flip of the collective spin can result in the sudden emergence of chaotic dynamics.Overall, we provide a comprehensive road map of the possible dynamics that arise in the unbalanced, open Dicke model in the form of a phase diagram in the plane of the two interaction strengths.Hence, we lay out the foundations to make further advances in the study of the fingerprint of semiclassical chaos when considering the master equation of the unbalanced Dicke model, thus, providing the possibility of studying a manifestation of quantum chaos in a specific, experimentally realizable system.

arXiv:2004.04486Physical Review ResearchJul 23, 202043 citations

We report on a theoretical and experimental study of state-selective differential single-electron transfer cross sections between

{\mathrm{Na}}^{+}

ions and

\mathrm{Rb}(5s,5p)

atoms at collision energies of 2, 5, and 7 keV. A two-center multichannel semiclassical impact parameter close-coupling method with straight-line trajectories was used to obtain single-electron capture amplitudes. By combining with the eikonal approximation, we calculated the angular differential cross sections. These results are compared to the experimental data obtained with Rb targets cooled in a magnetic optical trap. It is shown that there is generally a good agreement between the present calculations and the experiments. In spite of the higher resolution offered from the cold target, the rapid oscillations in the differential cross sections are not resolved by the experiments.