Dynamics of Bose-Einstein Condensates in Josephson Junctions PDF Download
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Author: Jaclyn Semple
Publisher:
ISBN:
Category :
Languages : en
Pages : 212
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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.
Author: Jaclyn Semple
Publisher:
ISBN:
Category :
Languages : en
Pages : 212
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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.
Author: Kaspar Sakmann
Publisher: Springer Science & Business Media
ISBN: 3642228666
Category : Science
Languages : en
Pages : 135
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Book Description
At extremely low temperatures, clouds of bosonic atoms form what is known as a Bose-Einstein condensate. Recently, it has become clear that many different types of condensates -- so called fragmented condensates -- exist. In order to tell whether fragmentation occurs or not, it is necessary to solve the full many-body Schrödinger equation, a task that remained elusive for experimentally relevant conditions for many years. In this thesis the first numerically exact solutions of the time-dependent many-body Schrödinger equation for a bosonic Josephson junction are provided and compared to the approximate Gross-Pitaevskii and Bose-Hubbard theories. It is thereby shown that the dynamics of Bose-Einstein condensates is far more intricate than one would anticipate based on these approximations. A special conceptual innovation in this thesis are optimal lattice models. It is shown how all quantum lattice models of condensed matter physics that are based on Wannier functions, e.g. the Bose/Fermi Hubbard model, can be optimized variationally. This leads to exciting new physics.
Author: Lev. P. Pitaevskii
Publisher: Oxford University Press
ISBN: 9780198507192
Category : Science
Languages : en
Pages : 392
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Book Description
Bose-Einstein Condensation represents a new state of matter and is one of the cornerstones of quantum physics, resulting in the 2001 Nobel Prize. Providing a useful introduction to one of the most exciting field of physics today, this text will be of interest to a growing community of physicists, and is easily accessible to non-specialists alike.
Author: Junpeng Hou
Publisher:
ISBN:
Category : Bose-Einstein condensation
Languages : en
Pages :
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Book Description
In this dissertation, we study a range of exotic quantum phases and dynamics in BoseEinstein condensates (BECs) with spin-orbit (SO) coupling. Firstly, inspired by the recent experimental progresses in engineering supersolid stripe states in a SO-coupled BEC, we conjecture a new quantum state of matter called "superfluid-qausicrystal", in which quasicrystalline orders form spontaneously in the ground states of the BECs. We propose a realistic setup to prepare and observe this exotic quantum states and confirm its existence through both variational ansatz analysis and direct simulation of mean-field Gross-Pitaevskii equation (GPE). Moreover, we have identified rich phase diagram including superfluid-qausicrystals, supersoilds and plane-wave phases. By utilizing the double-well band structure of a SO-coupled BEC, we propose and investigate a momentum-pace Josephson junction (MSJJ). We show that, under an extra pair of Raman lasers, the two band minimums in momentum space can be weakly coupled. In such a MSJJ, Josephson currents can be induced not only by applying the equivalent of "voltages", but also by tuning tunneling phases. We characterize the MSJJs through both full mean-field analysis and a concise two-level model and demonstrate the important role of interactions between atoms. Besides, we experimentally demonstrate that this can be a route for realizing a striped BEC, providing an accessible platform to investigate the excitation spectra and other important properties of supersolid-like states. We observe coherent Rabi oscillations in momentum space between two band minima and demonstrate a long lifetime of the ground state, which find good agreements with mean-field simulations. Finally, we theoretically conceive and experimentally demonstrate a non-magnetic one-way spin switch device using a SO-coupled BEC subjected to a moving spin-independent repulsive dipole potential. We show that the physical foundation of this unidirectional device is based on the breakdown of Galilean invariance in the presence of SO coupling. The experimental observation, the numerical simulations and the theoretic interpretations are consistent with the others
Author: Marine Pigneur
Publisher: Springer Nature
ISBN: 3030528448
Category : Science
Languages : en
Pages : 204
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Book Description
The relaxation of isolated quantum many-body systems is a major unsolved problem of modern physics, which is connected to many fundamental questions. However, realizations of quantum many-body systems which are both well isolated from their environment and accessible to experimental study are scarce. In recent years, the field has experienced rapid progress, partly attributed to ultra-cold atoms. This book presents the experimental study of a relaxation phenomenon occurring in a one-dimensional bosonic Josephson junction. The system consists of two 1D quasi Bose-Einstein condensates of 87Rb, magnetically trapped on an atom chip. Using radio-frequency dressing, the author deforms a single harmonic trap, in which the atoms are initially condensed, into a double-well potential and realizes a splitting of the wave function. A large spatial separation and a tilt of the double-well enable the preparation of a broad variety of initial states by precisely adjusting the initial population and relative phase of the two wave packets, while preserving the phase coherence. By re-coupling the two wave packets, the author investigates tunneling regimes such as Josephson (plasma) oscillations and macroscopic quantum self-trapping. In both regimes, the tunneling dynamics exhibits a relaxation to a phase-locked equilibrium state contradicting theoretical predictions. The experimental results are supported with an empirical model that allows quantitative discussions according to various experimental parameters. These results illustrate how strongly the non-equilibrium dynamics differ from the equilibrium one, which is well described by thermodynamics and statistical physics.
Author: Keith Burnett (Ed); Mark Edwar
Publisher: DIANE Publishing
ISBN: 0788137409
Category :
Languages : en
Pages : 213
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Book Description
Among the most remarkable effects that quantum mechanics adds to the catalog of the thermal properties of matter is "condensation" of an ideal gas of identical particles into a single quantum state, the principle of which was discovered in the theory of statistical mechanics by Bose and Einstein in the 1920s. Bose-Einstein condensation (BEC) is a mechanism for producing a macroscopic quantum system, and is exemplary of the macroscopic quantum phenomena of superconductivity and superfluidity.These 15 papers provide an introduction to current work on BEC.
Author: Tarik Berrada
Publisher: Springer
ISBN: 3319272330
Category : Science
Languages : en
Pages : 244
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Book Description
This thesis demonstrates a full Mach–Zehnder interferometer with interacting Bose–Einstein condensates confined on an atom chip. It relies on the coherent manipulation of atoms trapped in a magnetic double-well potential, for which the author developed a novel type of beam splitter. Particle-wave duality enables the construction of interferometers for matter waves, which complement optical interferometers in precision measurement devices, both for technological applications and fundamental tests. This requires the development of atom-optics analogues to beam splitters, phase shifters and recombiners. Particle interactions in the Bose–Einstein condensate lead to a nonlinearity, absent in photon optics. This is exploited to generate a non-classical state with reduced atom-number fluctuations inside the interferometer. This state is then used to study the interaction-induced dephasing of the quantum superposition. The resulting coherence times are found to be a factor of three longer than expected for coherent states, highlighting the potential of entanglement as a resource for quantum-enhanced metrology.
Author: Shahar Levy
Publisher:
ISBN:
Category :
Languages : en
Pages : 75
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Book Description
Author: Sergey Nazarenko
Publisher: Springer Science & Business Media
ISBN: 3642159419
Category : Science
Languages : en
Pages : 287
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Book Description
Wave Turbulence refers to the statistical theory of weakly nonlinear dispersive waves. There is a wide and growing spectrum of physical applications, ranging from sea waves, to plasma waves, to superfluid turbulence, to nonlinear optics and Bose-Einstein condensates. Beyond the fundamentals the book thus also covers new developments such as the interaction of random waves with coherent structures (vortices, solitons, wave breaks), inverse cascades leading to condensation and the transitions between weak and strong turbulence, turbulence intermittency as well as finite system size effects, such as “frozen” turbulence, discrete wave resonances and avalanche-type energy cascades. This book is an outgrow of several lectures courses held by the author and, as a result, written and structured rather as a graduate text than a monograph, with many exercises and solutions offered along the way. The present compact description primarily addresses students and non-specialist researchers wishing to enter and work in this field.
Author: Christian Groß
Publisher: Springer Science & Business Media
ISBN: 3642256376
Category : Science
Languages : en
Pages : 123
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Book Description
Interferometry, the most precise measurement technique known today, exploits the wave-like nature of the atoms or photons in the interferometer. As expected from the laws of quantum mechanics, the granular, particle-like features of the individually independent atoms or photons are responsible for the precision limit, the shot noise limit. However this “classical” bound is not fundamental and it is the aim of quantum metrology to overcome it by employing entanglement among the particles. This work reports on the realization of spin-squeezed states suitable for atom interferometry. Spin squeezing was generated on the basis of motional and spin degrees of freedom, whereby the latter allowed the implementation of a full interferometer with quantum-enhanced precision.
