Transport of Bose-Einstein Condensates Through Two Dimensional Cavities - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Transport of Bose-Einstein Condensates Through Two Dimensional Cavities write by Timo Hartmann. This book was released on 2015. Transport of Bose-Einstein Condensates Through Two Dimensional Cavities available in PDF, EPUB and Kindle. The recent experimental advances in manipulating ultra-cold atoms make it feasible to study coherent transport of Bose-Einstein condensates (BEC) through various mesoscopic structures. In this work the quasi-stationary propagation of BEC matter waves through two dimensional cavities is investigated using numerical simulations within the mean-field approach of the Gross-Pitaevskii equation. The focus is on the interplay between interference effects and the interaction term in the non-linear wave equation. One sees that the transport properties show a complicated behaviour with multi-stability, hysteresis and dynamical instabilities for non-vanishing interaction. Furthermore, the prominent weak localization effect, which is a robust interference effect emerging after taking a configuration average, is reduced and partially inverted for non-vanishing interaction.
Transport and Turbulence in Quasi-Uniform and Versatile Bose-Einstein Condensates
Transport and Turbulence in Quasi-Uniform and Versatile Bose-Einstein Condensates - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Transport and Turbulence in Quasi-Uniform and Versatile Bose-Einstein Condensates write by Gauthier Guillaume. This book was released on 2020-09-26. Transport and Turbulence in Quasi-Uniform and Versatile Bose-Einstein Condensates available in PDF, EPUB and Kindle. 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.
Nonlinear Localization, Controlled Transport and Collapse Suppression in Bose-Einstein Condensates
Nonlinear Localization, Controlled Transport and Collapse Suppression in Bose-Einstein Condensates - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Nonlinear Localization, Controlled Transport and Collapse Suppression in Bose-Einstein Condensates write by Jasur Abdullaev. This book was released on 2014. Nonlinear Localization, Controlled Transport and Collapse Suppression in Bose-Einstein Condensates available in PDF, EPUB and Kindle. This thesis includes theoretical studies regarding stability and manipulation of Bose-Einstein condensates (BECs) of ultra-cold atoms in 2D trapping geometry, as well as formation of steady states of exciton-polariton Bose-Einstein condensates created in solid states. We analyze and numerically model the dynamics and localization of the condensates using mean-field model. Chapter 1 contains an introduction to the physics of ultra-cold atom BEC and excitonpolariton BEC which provides a framework for the work presented in later chapters. In Chapter 2, we consider a method for achieving dynamically controllable transport of highly mobile matter-wave solitons in an ultra-cold atom BEC with attractive interparticle interaction loaded into a driven two-dimensional optical lattice. Our numerical analysis based on the mean-field model and the theory based on the effective particle approach demonstrate that fast, time-periodic rocking of the two-dimensional optical lattice enables efficient stabilization and manipulation of spatially localized matter wave packets via induced reconfigurable mobility channels. Chapter 3 consists of an investigation of the instability - collapse of a BEC with attractive interactions. In this chapter we explore the influence of an orbital angular momentum on the collapse of vortex-free elliptic clouds of Bose-Einstein condensates trapped in a radially symmetric harmonic potential or a rotating elliptic potential. The results of our analysis show that the number of trapped ultracold atoms corresponding to the collapse threshold can be radically increased for such rotating nonlinear matter waves in a radially harmonic trap. The results corresponding to a BEC cloud confined in a rotating elliptic trap show that the elongated stationary states can be parallel or perpendicular to the long axis of the trap and display bistable nature. In Chapter 4, we examine spatial localization and dynamical stability of Bose-Einstein condensates of exciton-polaritons in microcavities under the condition of off-resonant spatially inhomogeneous optical pumping both with and without a harmonic trapping potential. We employ the open-dissipative Gross-Pitaevskii model for describing an incoherently pumped polariton condensate coupled to an exciton reservoir. We reveal that spatial localization of the steady-state condensate occurs due to effective self-trapping created by the polariton flows, regardless of the presence of the external potential. A ground state of the polariton condensate with repulsive interactions between the quasiparticles represents a dynamically stable bright dissipative soliton. We also investigate the conditions for sustaining spatially localized structures, with nonzero angular momentum, in the form of single-charge vortices. Chapter 5 consider the existence of novel spatially localized states of exciton-polariton Bose-Einstein condensates in semiconductor microcavities with fabricated periodic inplane potentials. Our theory shows that, under the conditions of continuous nonresonant pumping, localization is observed for a wide range of optical pump parameters due to effective potentials self-induced by the polariton flows in the spatially periodic system. We show that the self-localization of exciton-polaritons in the lattice may occur both in the gaps and bands of the single-particle linear spectrum, and is dominated by the effects of gain and dissipation rather than the structured potential, in sharp contrast to the conservative condensates of ultra-cold alkali atoms.
Probing Two-Dimensional Quantum Fluids with Cavity Optomechanics
Probing Two-Dimensional Quantum Fluids with Cavity Optomechanics - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Probing Two-Dimensional Quantum Fluids with Cavity Optomechanics write by Yauhen Sachkou. This book was released on 2020-07-17. Probing Two-Dimensional Quantum Fluids with Cavity Optomechanics available in PDF, EPUB and Kindle. Superfluid helium is a quantum liquid that exhibits a range of counter-intuitive phenomena such as frictionless flow. Quantized vortices are a particularly important feature of superfluid helium, and all superfluids, characterized by a circulation that can only take prescribed integer values. However, the strong interactions between atoms in superfluid helium prohibit quantitative theory of vortex behaviour. Experiments have similarly not been able to observe coherent vortex dynamics. This thesis resolves this challenge, bringing microphotonic techniques to bear on two-dimensional superfluid helium, observing coherent vortex dynamics for the first time, and achieving this on a silicon chip. This represents a major scientific contribution, as it opens the door not only to providing a better understanding of this esoteric quantum state of matter, but also to building new quantum technologies based upon it, and to understanding the dynamics of astrophysical superfluids such as those thought to exist in the core of neutron stars.
Bose-Einstein Condensation in Two-dimensional Traps
Bose-Einstein Condensation in Two-dimensional Traps - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Bose-Einstein Condensation in Two-dimensional Traps write by Juan Pablo Fernández. This book was released on 2004. Bose-Einstein Condensation in Two-dimensional Traps available in PDF, EPUB and Kindle.
