Non Classical States Of Matter In Spinor Bose Einstein Condensates

Author : Maitreyi Jayaseelan
Publisher :
ISBN 13 :
Total Pages : 111 pages
Book Rating : 4.:/5 (125 download)

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Download or read book Topological Atom-optics with Spinor Bose-Einstein Condensates written by Maitreyi Jayaseelan and published by . This book was released on 2021 with total page 111 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Mathematical structure can connect diverse physical systems, allowing similar topological and collective behaviors to emerge in systems that are microscopically different. In coherent laser light in optics and in the coherent matter-waves of Bose-Einstein condensates, we find a compelling atom-optic analogy. The polarization states of transverse monochromatic lightand two Zeeman spin states in a Bose-Einstein condensate are both pseudo-spin-1/2 systems, furnishing this analogy with systems with a vector description. Within this pseudo-spin-1/2 atom-optic framework, the rich physics of singularities can be explored: by sculpting the phase and population distribution of the atomic spin states with a coherent optical Raman imprinting method, many singular structures that have been created in optics have also been created and characterized in atoms. However, even in transverse monochromatic optical fields, light's spin-1 nature allows the inherently higher-order tensor field that describes it to host further topological structures and new classes of vortices. These vortices occur within the different frameworks of both atomic physics and classical optics, with each field employing its own language to describe them. We experimentally generate these vortices in a 87 Rb Bose-Einstein condensate and reconstruct the associated spin-1 topological structures using atomic polarimetry. We extend the atom-optic analogy to the spin-1 case, establishing correspondences between these characteristically spin-1 structures in the optical and atomic wavefields. The topology of vector and tensor wavefields results in surpising features when we consider the coupling of angular momenta in these systems. In optics, spin-orbit coupling-between the internal polarization and external orbital angular momentum degrees of freedom-has been shown to display a topologically non-trivial Mb̲ius strip structure that generalizes to a torus knot and link topology in multifrequency fields. Knots and links are challenging to create experimentally, since they require a mathematical and physical understanding of the underlying topology of the media supporting these structures, as well as good experimental control over the system. We realize atomic Möbius strip topologies in the spin-1 manifold of a Bose-Einstein condensate using coherent control techniques, and we use visualizations from atomic physics and optics to reconstruct the topological structure from the data. We further employ the higher-spin (atomic spin-2) manifold to realize more complex torus knot and link topologies, emulating structures created in bichromatic optical fields. These atomic torus knot and link structures are reconstructed with similar visualization techniques. Finally, we show that the fractionally quantized circulations of superfluid flows in these vortices in the atomic system can be identified with fractionally quantized flows of angular momentum in the analogous optical field. These connections add to recent developments in the treatment of light as a quantum fluid. They also illustrate how microscopically different systems-optical fields are governed by Maxwell's equations, while atomic systems are governed by the Schrödinger or Gross-Pitaevskii equation-can display closely related macroscopic behaviors. The emergence of macroscopic collective behavior from microscopic dynamics is a topic that frequently arises in many fields. In quantum mechanics, an example is in the collapse of a measured quantum-mechanical wavefunction. The irreversible nature of projective measurements and the reversible dynamics of the Schrödinger equation are able to be reconciled in statistical or stochastic treatments. The connection is made quantitative through an arrow of time measure that characterizes a quantum system's evolution. Fluctuation theorems that constrain the probability distribution for the arrow of time relate the irreversibility of wavefunction collapse to information obtained from a quantum measurement. We explore these ideas through an experimental weak measurement of spin state performed on an ultracold atomic cloud, constructing arrow of time statistics and showing the fluctuation theorem for the measured atomic population distribution"--Pages x-xi.