Dynamics of Two-component Bose-Einstein Condensates


Book Description

I explored the vortex dynamics in homonuclear species two-component Bose-Einstein condensates (BECs) based on the knowledge of vortex dynamics in one-component BECs. The vortex dynamics in BECs depends on the background elds induced by di erent external potentials and other vortices. The motion of vortices is numerically computed and the numerical results are compared to the theoretical formulas where possible. In the study of the vortex-vortex interaction dynamics in one-component BECs, a power law relationship between the motion of the vortices and their separation distance is depicted. In addition to that, the relationship between the linear and the angular velocities of the vortices is found to be similar to the relationship between the tangential and the angular velocities of classical uid vortices. In the case of two-component BEC dynamics, two di erent cases are studied: one without atomic inter-conversion between the two components and the other with atomic inter-conversion. The stability analysis of the two-component BECs is conducted to identify the stable regions as well as the regions of mixed and separated states. When a vortex is seeded in one component, this vortex induces a hump in the other component at the same location as the vortex, which leads to the vortexhump dynamics. The vortex-hump-vortex-hump interaction dynamics without atomic inter-conversion depicts a power law relation between the motion of vortex-humps and the separation distance; whereas, the vortex-hump-vortex-hump interaction dynamics with atomic inter-conversion reveals a more complex relation between the motion of vortex-humps and the separation distance.







Quantum Hydrodynamics in One- and Two-component Bose-Einstein Condensates


Book Description

Several prototypical experiments concerning quantum hydrodynamics are realized in this thesis using one and two-component Bose-Einstein condensates (BECs). The experiments are conducted with an experimental apparatus built at WSU that is capable of reliably producing 87Rb BECs and 40K degenerate Fermi gases (DFGs). The apparatus, which has undergone many modifications and upgrades since it was first built, will be described in detail. The upgrades include the addition of fermionic potassium atoms, installation of a fully electromagnetic Ioffe-Pritchard type trap with excellent optical access to the BEC, and the addition of an optical dipole trap (and optical lattices).




Emergent Nonlinear Phenomena in Bose-Einstein Condensates


Book Description

This book, written by experts in the fields of atomic physics and nonlinear science, covers the important developments in a special aspect of Bose-Einstein condensation, namely nonlinear phenomena in condensates. Topics covered include bright, dark, gap and multidimensional solitons; vortices; vortex lattices; optical lattices; multicomponent condensates; mathematical methods/rigorous results; and the beyond-the-mean-field approach.







Universal Themes of Bose-Einstein Condensation


Book Description

Covering general theoretical concepts and the research to date, this book demonstrates that Bose-Einstein condensation is a truly universal phenomenon.




Transport and Turbulence in Quasi-Uniform and Versatile Bose-Einstein Condensates


Book Description

Advancing the experimental study of superfluids relies on increasingly sophisticated techniques. We develop and demonstrate the loading of Bose-Einstein condensates (BECs) into nearly arbitrary trapping potentials, with a resolution improved by a factor of seven when compared to reported systems. These advanced control techniques have since been adopted by several cold atoms labs around the world. How this BEC system was used to study 2D superfluid dynamics is described. In particular, negative temperature vortex states in a two-dimensional quantum fluid were observed. These states were first predicted by Lars Onsager 70 years ago and have significance to 2D turbulence in quantum and classical fluids, long-range interacting systems, and defect dynamics in high-energy physics. These experiments have established dilute-gas BECs as the prototypical system for the experimental study of point vortices and their nonequilibrium dynamics. We also developed a new approach to superfluid circuitry based on classical acoustic circuits, demonstrating its conceptual and quantitative superiority over previous lumped-element models. This has established foundational principles of superfluid circuitry that will impact the design of future transport experiments and new generation quantum devices, such as atomtronics circuits and superfluid sensors.




Universal Themes of Bose-Einstein Condensation


Book Description

Following an explosion of research on Bose–Einstein condensation (BEC) ignited by demonstration of the effect by 2001 Nobel prize winners Cornell, Wieman and Ketterle, this book surveys the field of BEC studies. Written by experts in the field, it focuses on Bose–Einstein condensation as a universal phenomenon, covering topics such as cold atoms, magnetic and optical condensates in solids, liquid helium and field theory. Summarising general theoretical concepts and the research to date - including novel experimental realisations in previously inaccessible systems and their theoretical interpretation - it is an excellent resource for researchers and students in theoretical and experimental physics who wish to learn of the general themes of BEC in different subfields.







Dynamics of Bose-Einstein Condensates in Josephson Junctions


Book Description

We numerically solve the Gross-Pitaevskii equation and the Bogoliubov de Gennes equations for a double well potential in order to model the dynamics of a Bose-Einstein condensate in a Josephson junction. First, the two dynamical regimes of the Josephson junction, that is, Josephson oscillations and self-trapping, are investigated under the application of a large sudden perturbation. It is found that the Josephson dynamics have a strong dependence on the strength of the interatomic interaction, and we observe the breakdown of the two-mode approximation. Second, we study the control of the dynamics through the use of a time-dependent, tilted double well potential. In the context of complete population transfer, the effect of the interactions on the adiabaticity and self-trapping is discussed in terms of a Landau-Zener-like model. We then explore the splitting of the condensate and the resulting dynamical behaviour by keeping the interaction strength constant, but changing the rate of the tilt sweep. Lastly, we examine the effect of the tilt sweep rate on the dynamics of population transfer. We observe a dependence of the self-trapping on the adiabaticity.