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Academic literature on the topic 'Reconnection of quantum vortices'

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Published: 11 March 2023

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Journal articles on the topic "Reconnection of quantum vortices"

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Fonda, Enrico, Katepalli R. Sreenivasan, and Daniel P. Lathrop. "Reconnection scaling in quantum fluids." Proceedings of the National Academy of Sciences 116, no. 6 (January 22, 2019): 1924–28. http://dx.doi.org/10.1073/pnas.1816403116.

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Fundamental to classical and quantum vortices, superconductors, magnetic flux tubes, liquid crystals, cosmic strings, and DNA is the phenomenon of reconnection of line-like singularities. We visualize reconnection of quantum vortices in superfluid4He, using submicrometer frozen air tracers. Compared with previous work, the fluid was almost at rest, leading to fewer, straighter, and slower-moving vortices. For distances that are large compared with vortex diameter but small compared with those from other nonparticipating vortices and solid boundaries (called here the intermediate asymptotic region), we find a robust 1/2-power scaling of the intervortex separation with time and characterize the influence of the intervortex angle on the evolution of the recoiling vortices. The agreement of the experimental data with the analytical and numerical models suggests that the dynamics of reconnection of long straight vortices can be described by self-similar solutions of the local induction approximation or Biot–Savart equations. Reconnection dynamics for straight vortices in the intermediate asymptotic region are substantially different from those in a vortex tangle or on distances of the order of the vortex diameter.
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Lipniacki, Tomasz. "Evolution of quantum vortices following reconnection." European Journal of Mechanics - B/Fluids 19, no. 3 (May 2000): 361–78. http://dx.doi.org/10.1016/s0997-7546(00)00123-0.

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Enciso, Alberto, and Daniel Peralta-Salas. "Vortex reconnections in classical and quantum fluids." SeMA Journal 79, no. 1 (November 24, 2021): 127–37. http://dx.doi.org/10.1007/s40324-021-00277-8.

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AbstractWe review recent rigorous results on the phenomenon of vortex reconnection in classical and quantum fluids. In the context of the Navier–Stokes equations in $$\mathbb {T}^3$$ T 3 we show the existence of global smooth solutions that exhibit creation and destruction of vortex lines of arbitrarily complicated topologies. Concerning quantum fluids, we prove that for any initial and final configurations of quantum vortices, and any way of transforming one into the other, there is an initial condition whose associated solution to the Gross–Pitaevskii equation realizes this specific vortex reconnection scenario. Key to prove these results is an inverse localization principle for Beltrami fields and a global approximation theorem for the linear Schrödinger equation.
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Rorai, C., J. Skipper, R. M. Kerr, and K. R. Sreenivasan. "Approach and separation of quantised vortices with balanced cores." Journal of Fluid Mechanics 808 (November 4, 2016): 641–67. http://dx.doi.org/10.1017/jfm.2016.638.

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The scaling laws for the reconnection of isolated pairs of quantised vortices are characterised by numerically integrating the three-dimensional Gross–Pitaevskii equations, the simplest mean-field equations for a quantum fluid. The primary result is the identification of distinctly different temporal power laws for the pre- and post-reconnection separation distances $\unicode[STIX]{x1D6FF}(t)$ for two configurations. For the initially anti-parallel case, the scaling laws before and after the reconnection time $t_{r}$ obey the dimensional $\unicode[STIX]{x1D6FF}\sim |t_{r}-t|^{1/2}$ prediction with temporal symmetry about $t_{r}$ and physical space symmetry about the mid-point between the vortices $x_{r}$. The extensions of the vortex lines close to reconnection form the edges of an equilateral pyramid. For all of the initially orthogonal cases, $\unicode[STIX]{x1D6FF}\sim |t_{r}-t|^{1/3}$ before reconnection and $\unicode[STIX]{x1D6FF}\sim |t-t_{r}|^{2/3}$ after reconnection are respectively slower and faster than the dimensional prediction. For both configurations, smooth scaling laws are generated due to two innovations. The first innovation is to use an initial low-energy vortex-core density profile that suppresses unwanted density fluctuations as the vortices evolve in time. The other innovation is the accurate identification of the position of the vortex cores from a pseudo-vorticity constructed on the three-dimensional grid from the gradients of the wave function. These trajectories allow us to calculate the Frenet–Serret frames and the curvature of the vortex lines, secondary results that might hold clues for the origin of the differences between the scaling laws of the two configurations. Reconnection takes place in a reconnection plane defined by the average tangents $\boldsymbol{T}_{av}$ and curvature normal $\boldsymbol{N}_{av}$ directions of the pseudo-vorticity curves at the points of closest approach, at time $t\approx t_{r}$. To characterise the structure further, lines are drawn that connect the four arms that extend from the reconnection plane, from which four angles $\unicode[STIX]{x1D703}_{i}$ between the lines are defined. Their sum is convex or hyperbolic, that is $\sum _{i=1,4}\unicode[STIX]{x1D703}_{i}>360^{\circ }$, for the orthogonal cases, as opposed to the acute angles of the pyramid found for the anti-parallel initial conditions.
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Galantucci, Luca, Andrew W. Baggaley, Nick G. Parker, and Carlo F. Barenghi. "Crossover from interaction to driven regimes in quantum vortex reconnections." Proceedings of the National Academy of Sciences 116, no. 25 (June 6, 2019): 12204–11. http://dx.doi.org/10.1073/pnas.1818668116.

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Reconnections of coherent filamentary structures play a key role in the dynamics of fluids, redistributing energy and helicity among the length scales, triggering dissipative effects, and inducing fine-scale mixing. Unlike ordinary (classical) fluids where vorticity is a continuous field, in superfluid helium and in atomic Bose–Einstein condensates (BECs) vorticity takes the form of isolated quantized vortex lines, which are conceptually easier to study. New experimental techniques now allow visualization of individual vortex reconnections in helium and condensates. It has long being suspected that reconnections obey universal laws, particularly a universal scaling with time of the minimum distance between vortices δ. Here we perform a comprehensive analysis of this scaling across a range of scenarios relevant to superfluid helium and trapped condensates, combining our own numerical simulations with the previous results in the literature. We reveal that the scaling exhibits two distinct fundamental regimes: a δ∼t1/2 scaling arising from the mutual interaction of the reconnecting strands and a δ∼t scaling when extrinsic factors drive the individual vortices.
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Kimura, Y., and H. K. Moffatt. "Reconnection of skewed vortices." Journal of Fluid Mechanics 751 (June 20, 2014): 329–45. http://dx.doi.org/10.1017/jfm.2014.233.

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AbstractBased on experimental evidence that vortex reconnection commences with the approach of nearly antiparallel segments of vorticity, a linearised model is developed in which two Burgers-type vortices are driven together and stretched by an ambient irrotational strain field induced by more remote vorticity. When these Burgers vortices are exactly antiparallel, they are annihilated on the strain time-scale, independent of kinematic viscosity $\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}\nu $ in the limit $\nu \rightarrow 0$. When the vortices are skew to each other, they are annihilated under this action over a local extent that increases exponentially in the stretching direction, with clear evidence of reconnection on the same strain time-scale. The initial helicity associated with the skewed geometry is eliminated during the process of reconnection. The model applies equally to the reconnection of weak magnetic flux tubes under the action of a strain field, when Lorentz forces are negligible.
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Paoletti, M. S., Michael E. Fisher, and D. P. Lathrop. "Reconnection dynamics for quantized vortices." Physica D: Nonlinear Phenomena 239, no. 14 (July 2010): 1367–77. http://dx.doi.org/10.1016/j.physd.2009.03.006.

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Suaza Jaque, Ruben, and Oscar Velasco Fuentes. "Reconnection of orthogonal cylindrical vortices." European Journal of Mechanics - B/Fluids 62 (March 2017): 51–56. http://dx.doi.org/10.1016/j.euromechflu.2016.11.001.

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Andryushchenko, V. A., L. P. Kondaurova, and S. K. Nemirovskii. "Dynamics of Quantized Vortices Before Reconnection." Journal of Low Temperature Physics 185, no. 5-6 (April 13, 2016): 377–83. http://dx.doi.org/10.1007/s10909-016-1614-9.

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Califano, F., M. Faganello, F. Pegoraro, and F. Valentini. "Solar wind interaction with the Earth's magnetosphere: the role of reconnection in the presence of a large scale sheared flow." Nonlinear Processes in Geophysics 16, no. 1 (January 16, 2009): 1–10. http://dx.doi.org/10.5194/npg-16-1-2009.

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Abstract. The Earth's magnetosphere and solar wind environment is a laboratory of excellence for the study of the physics of collisionless magnetic reconnection. At low latitude magnetopause, magnetic reconnection develops as a secondary instability due to the stretching of magnetic field lines advected by large scale Kelvin-Helmholtz vortices. In particular, reconnection takes place in the sheared magnetic layer that forms between adjacent vortices during vortex pairing. The process generates magnetic islands with typical size of the order of the ion inertial length, much smaller than the MHD scale of the vortices and much larger than the electron inertial length. The process of reconnection and island formation sets up spontaneously, without any need for special boundary conditions or initial conditions, and independently of the initial in-plane magnetic field topology, whether homogeneous or sheared.
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Dissertations / Theses on the topic "Reconnection of quantum vortices"

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Rorai, Cecilia. "Vortex reconnection in superfluid helium." Doctoral thesis, Università degli studi di Trieste, 2012. http://hdl.handle.net/10077/7868.

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2010/2011
La presente tesi concerne la modellizzazione e simulazione numerica, attraverso l'equazione di Gross-Pitaevskii (chiamata anche equazione di Schroedinger non lineare), della dinamica dei vortici quantistici nell'elio superfluido e in particolare del fenomeno della riconnessione. La riconnessione si verifica qualora due vortici approssimativamente antiparalleli, si intersecano e si scambiano le estremità. Questo fenomeno è stato osservato sperimentalmente e risulta essere una caratteristica essenziale della turbolenza quantistica.
XXIII Ciclo
1983
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Beardsell, Guillaume. "Spectral simulations of the reconnection process of two vortices." Master's thesis, Université Laval, 2016. http://hdl.handle.net/20.500.11794/26651.

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Tableau d’honneur de la Faculté des études supérieures et postdoctorales, 2015-2016
Ce mémoire investigue le phénomène de reconnexion visqueuse de deux tourbillons initialement placés de façon orthogonale ou antiparallèle. Les équations de Navier-Stokes pour un fluide incompressible sont résolues directement (DNS) à l’aide d’un algorithme pseudospectral utilisant des expansions périodiques dans les trois directions cartésiennes. La condition de circulation nulle inhérente à cette méthode numérique est contournée en résolvant les équations dans un repère tournant approprié. Une méthode simple utilisant des lignes de vorticité est proposée afin de calculer le pourcentage de reconnexion instantané η de deux tourbillons. Cette méthode est également employée pour séparer le champ de vorticité en ses composantes reconnectées et non-reconnectées, ce qui facilite l’identification visuelle des différentes étapes du processus de reconnexion. Finalement, l’échelle de temps de la reconnexion tourbillonnaire Trec est calculée pour différents nombres de Reynolds (500 ≤ Re ≤ 10000). Il est trouvé que l’ordre de grandeur de Trec varie de façon continue de [symbol] à mesure que Re augmente.
This work focuses on the viscous reconnection phenomenon of two vortex tubes that are initially antiparallel or orthogonal to each other. The incompressible Navier-stokes equations are solved directly (DNS) using a Fourier pseudospectral algorithm with triply periodic boundary conditions. The associated zero-circulation constraint is circumvented by solving the governing equations in a proper rotating frame of reference. A simple method using vortex lines is proposed to compute the instantaneous reconnection level η of two vortices. The proposed method is also used to split the vorticity field into its reconnected and non-reconnected parts, which allows for a clear and intuitive visual identification of the different reconnection phases. Finally, the Reynolds number dependence of the reconnection timescale Trec is investigated for 500 ≤ Re ≤ 10000. The scaling is found to vary continuously as Re is increased from [symbol].
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Santos, André Cidrim. "Quantum turbulence and multicharged vortices in trapped atomic superfluids." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/76/76131/tde-31012018-154136/.

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In this thesis, we numerically investigate quantum turbulence in trapped atomic Bose-Einstein condensates (BECs). We first discuss the appropriate qualitative characterization of turbulence in these systems, showing the limitation of analogies with classical hydrodynamics and turbulence in large superfluid Helium experiments. Due to their lack of available length scales, our investigated systems can only fit the ultraquantum (or Vinen) type of quantum turbulence. Secondly, we propose experimentally feasible schemes for more controlled investigations of turbulence making use of dynamical instability of multicharged vortices as an onset for complex vortex dynamics. In two dimensions, our suggested scheme allows control over vortex polarization in the harmonically trapped system. This setup is then used to study how turbulence decays in such a scenario, through the phenomenological modeling of a vortex-number rate equation. As a consequence, we were able to identify that vortex annihilation in these trapped systems happens through a four-vortex process. For three dimensions, we have first provided a study on the decay of a quadruply-charged vortex, also in a harmonically trapped BEC. Having this setting as a comparison point, we propose a quasi-isotropic turbulent system, starting from a phase-imprinted initial state of two doubly-charged, anti-parallel vortices. The vortex turbulence arisen from such configuration was shown to agree with the Vinen turbulent regime, after we characterized specific features of its decay, such as the energy spectrum [E(k) ∼ k1] and the time evolution of the vortex-line density [L(t) ∼ t1]. Although these features have been frequently verified in the context of superfluid Helium turbulence, here this identification was for the first time done for realistic, trapped atomic BECs.
Nesta tese, investigamos numericamente a turbulência quântica em condensados de Bose- Einstein (BECs) aprisionados. Discutimos, inicialmente, a caracterização qualitativa apropriada para estes sistemas, mostrando a limitação de analogias tipicamente feitas com hidrodinâmica clássica e turbulência em grandes sistemas com Hélio superfluido. Devido às suas limitadas escalas espaciais, os sistemas investigados somente podem exibir o tipo de turbulência conhecida como ultra-quântica (ou de Vinen). Em seguida, propomos sistemas experimentalmente factíveis que permitem investigações mais controladas da turbulência, fazendo uso da instabilidade dinâmica de vórtices multi-carregados como ponto de partida para geração de dinâmicas complexas. Em duas dimensões, nossa proposta permite controle sobre a polarização de vórtices em sistemas aprisionados em potencial harmônico. Este arranjo é então utilizado no estudo do decaimento da turbulência nesse contexto, através de um modelo fenomenológico para equação que descreve a taxa de variação do número de vórtices. Como consequência, pudemos verificar que a aniquilação de vórtices dá-se através de um processo que envolve quatro vórtices. Em três dimensões, apresentamos um estudo do decaimento de um vórtice de carga topológica quatro, também em potencial harmônico. Mantendo em mente esse sistema a título de comparação, propomos um cenário turbulento, quase-isotrópico, partindo de um estado inicial formado por dois vórtices duplamente carregados, mas orientados anti-paralelamente. Verificamos que a turbulência decorrente desse arranjo coincide com a regime de Vinen analisando características do seu decaimento, especificamente obtendo o espectro de energia [E(k) ∼ k1] e evolução temporal da densidade de linhas de vórtices [L(t) ∼ t1]. Apesar de que essas características são comumente encontradas no contexto de Hélio superfluido, apresentamos pela primeira vez essa identificação no cenário realístico de BEC aprisionados.
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Tang, Jian-Ming. "Quantum mechanics of quantized vortices in dilute Bose gases /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/9682.

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Stagg, George William. "A numerical study of vortices and turbulence in quantum fluids." Thesis, University of Newcastle upon Tyne, 2016. http://hdl.handle.net/10443/3340.

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Quantum uids possess amazing properties of which two are particularly striking. Firstly they exhibit super uid ow, with the total absence of viscosity. Secondly, there are no excitations when the uid velocity (relative to some obstacle or surface) is slower than a critical value; above this velocity the ow becomes dissipative and macroscopic excitations are created in the form of quantised vortices with xed circulation proportional to Planck’s constant. In this thesis we numerically study the dynamics of quantum uids in the vicinity of obstacles and surfaces, from the production of a single vortex pair to the complex and chaotic motion of turbulent vortex tangles. This approach provides quantitative predictions for atomic Bose-Einstein condensates (BEC) and qualitative insight for super uid helium. We give detailed descriptions of the numerical schemes and present extensive numerical simulation of the Gross-Pitaevskii equation (GPE) and its variants at zero temperature and beyond, in both two and three dimensions. We study the wake that forms behind obstacles in the presence of a super uid ow, modelling atomic BEC experiments with moving laser-induced potentials, and explore the dependence on obstacle shape and size. We nd that suitable obstacles produce classicallike wakes consisting of clusters of vortices of the same polarity. Remarkably, symmetric wakes resemble those observed in classical viscous ow at low Reynolds number, despite the constrained vorticity. The structures are unstable, forming time-dependent asymmetric wakes similar to a classical Bénard–von Kármán vortex street. Motivated by the recentwork of Kwon et al. (Phys. Rev. A 90, 063627 (2014)), we model an atomic BEC experiment in which a trapped, oblate condensate is translated past a stationary, laser-induced obstacle. The critical velocity is exceeded and so vortices nucleate, forming a state of two-dimensional quantum turbulence. We explore the system at both zero-temperature and with thermal dissipation, modelled through a phenomenological term in the GPE. Our simulations provide insight into early stage evolution, not accessible experimentally, and into the decay of vortices by annihilation or passage out of the condensate. We use classical eld methods to simulate homogeneous Bose gases at nite temperature, from strongly non-equilibrium initial distributions to thermalised equilibrium states. We introduce a moving cylindrical potential and study how the thermal component of the gas a ects vortex nucleation. We have found that the critical velocity decreases with increasing temperature and scales with the speed of sound of the condensate. Above the critical velocity, vortices are nucleated as irregular vortex lines, rings, or vortex tangles. Finally we model the surfaces of walls and moving objects (such as wires, grids, propellers or spheres) in the presence of super uid ow, using a real rough boundary obtained via atomic force microscopy. We nd evidence pointing to the formation of a thin ‘super- uid boundary layer’ consisting of vortex loops and rings. As boundary layers usually arise from viscous forces, this is a surprising and intriguing result.
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Tejada, J., S. Velez, and R. Zarzuela. "Quantum Nanomagnetism." Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/35358.

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In this paper we discuss some of our most important results in quantum nanomagnets in the last twenty years. We start with the tunnelling of the magnetic moment in single domain particles, then we will move to molecular magnets to explain both resonant spin tunnelling and quantum magnetic deflagration and we will finish discussing the quantum phenomena recently observed in vortices of two dimensional disks and in type I superconductors. Probably the most important question to answer in the cases presented in this paper refers to the possibility to detect both coherent phonons and photons from the demagnetization process of molecular magnets as well as the fact to go deeper in the quantum phenomena observed in vortices of two dimensional disks and in type I superconductors. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35358
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HIENTZSCH, LARS ERIC. "Non linear Schrödinger equations and quantum fluids non vanishing at infinity: incompressible limits and quantum vortices." Doctoral thesis, Gran Sasso Science Institute, 2019. https://hdl.handle.net/20.500.12571/26564.

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This thesis concerns the mathematical analysis of some hydrodynamic models describing quantum fluids, namely fluids whose macroscopic behavior still exhibits quantum effects. The prototype model for such fluids is the quantum hydrodynamic (QHD) system arising as model in the description of phenomena like superfluidity, Bose-Einstein condensation (BEC), superconductivity, quantum plasmas and semi conductor devices. From a mathematical point of view, the QHD system is given by a compressible Euler system augmented by a stress tensor accounting for the quantum features in the fluid and which depends on the density and its derivatives. Stress tensors of this kind also appear in the theory of capillarity developed by Korteweg, one refers to these systems as Euler–Korteweg and Navier–Stokes-Korteweg systems when inviscid or viscous respectively. Motivated by the analysis of some physically relevant solutions like quantized vortices, we consider the system on the whole space complemented with non-zero boundary conditions at infinity. The Cauchy problem for finite and infinite energy weak solutions (including vortex solutions) is investigated. Our method relies on the equivalence between QHD systems and NLS type equations through the Madelung transforms and the polar factorization method that renders the equivalence rigorous for rough solutions. We are thus led to study the well-posedness theory in the energy space for a class of nonlinear Schrödinger equations with non-zero boundary conditions at infinity that we develop ad-hoc. Moreover, we consider the asymptotic behavior of weak solutions to the QHD system in a suitable scaling regime that is linked to the study of quantized vortices and can be interpreted as quantum counterpart of the low Mach number limit of classical fluid dynamics. The dispersion relation of acoustic waves turns out to be characterized by the Bogoliubov dispersion relation. In the scaling regime, the dynamics of vortex solutions can be asymptotically described by the Kirchhoff-Onsager ODE system. Secondly, we study the quantum Navier-Stokes (QNS) equations that can be understood as a viscous regularization of the QHD system with density dependent viscosity tensor. Physically, it is motivated by applications in the modeling of dissipative quantum fluids and as a showcase model for capillary fluids. We introduce global existence of finite energy weak solutions of the quantum Navier-Stokes system with non-trivial far-field behavior. In contrast to the results for the QHD system, the analysis of the QNS system is entirely based on techniques from fluid dynamics. Finally, we investigate the low Mach number limit and prove strong convergence to weak solutions of the incompressible Navier-Stokes equations for general ill-prepared data.
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Anzolin, Gabriele. "Astronomical applications of optical vortices." Doctoral thesis, Università degli studi di Padova, 2009. http://hdl.handle.net/11577/3426036.

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Optical vortices represent a particular class of wavefront dislocations characterized by a topological charge l. The surface of constant phase of an electromagnetic wave carrying an optical vortex has a helical structure and presents a singularity along the axis of the helicoid, where the phase is undefined. As a consequence, the intensity distribution of a vortex light beam contains a central dark region, where the intensity is zero due to destructive interference. Optical vortices can be produced by using phase modifying devices, i.e. particular optical elements possessing an optical singularity generally located at their center. The most efficient of them are fork holograms and spiral phase plates. In the last decade, the properties of optical vortices have found interesting applications in optical physics. Among these, the most promising are those in optical communications, nanotechnologies and biology. Optical vortices are attracting increasing attention also in astronomy, where the properties of such features of the electromagnetic radiation could provide a new approach to the study of astrophysical phenomena. The purpose of this Thesis is to present some possible applications of optical vortices to instrumental astronomy. In particular, this work is focused on the development and testing of new techniques to improve the performances of optical systems. Firstly, a method is proposed to improve the resolving power of a diffraction-limited telescope by means of an l = 1 fork hologram. Both the experiments and numerical simulations reveal that the superposition of the optical vortices produced by two light beams characterized by equal Airy intensity distributions present a detectable asymmetry even for separations that are one order of magnitude below the limit of the Rayleigh criterion. It is shown that this result can be achieved both with monochromatic and white light beams. We then present the first astronomical experiment in which we produced optical vortices in starlight beams with an l = 1 fork hologram placed at the focal plane of the Galileo 122 cm telescope in Asiago. By using the Lucky Imaging approach to reduce the effects of mediocre seeing conditions, we were able to observe the images of the optical vortices produced by the two main components of the multiple system alpha Her, in non-monochromatic light, and by the single star alpha Boo, using a narrow bandpass. In both cases, the intensity profiles of the observed optical vortices are in agreement with numerical simulations. Detailed analytical models and numerical simulations confirm that the spatial structure of an optical vortex produced by a phase modifying device is extremely sensitive to off-axis displacements of the input beam, especially when high values of the topological charge l are used. This property could be used to perform ground-based astrometric measurements with a precision competitive to standard PSF-fitting astrometry. The sensitivity to small off-axis displacements might also help to improve the tip/tilt correction of the wavefront for a small field of view. We discuss also the possible application of the nulling property of even-charged optical vortices to perform high-contrast coronagraphy. In this case, the nulling of the light of an on-axis star is achieved by using a spiral phase plate and a circular diaphragm as Lyot stop. In principle, this coronagraphic design is one of the very few that might allow direct imaging of extrasolar terrestrial planets. However, such remarkable performance is still strongly limited by the current techniques used to manufacture spiral phase plates. In the framework of projecting an l = 2 optical vortex coronagraph for visible wavelengths, we present the results of numerical simulations obtained considering a spiral phase plate with a surface subdivided in N discrete levels. A description of the experimental procedures used to test spiral phase plates manufactured with PMMA (polymethyl methacrylate) material is also given.
I vortici ottici rappresentano una particolare classe di dislocazioni dei fronti d'onda caratterizzate da una carica topologica l. La superficie di fase costante di un'onda elettromagnetica che trasporta un vortice ottico ha una struttura elicoidale. Lungo l'asse di questa elica è presente una singolarità in cui la fase non può essere definita. Di conseguenza, la distribuzione d'intensità di un fascio di luce contenente un vortice ottico presenta una zona centrale dove l'intensità è nulla per effetto dell’interferenza distruttiva. I vortici ottici possono essere prodotti utilizzando particolari elementi ottici detti phase modifying devices che modificano la fase di un'onda incidente. I più efficienti tra questi sono i fork holograms (ologrammi) e le spiral phase plates (maschere di fase). Negli ultimi anni, le proprietà dei vortici ottici hanno trovato interessanti applicazioni nei campi della fisica e dell'ottica. Tra queste, le più promettenti sono quelle in comunicazioni ottiche, nelle nanotecnologie ed in biologia. Recentemente, i vortici ottici stanno suscitando un crescente interesse anche nella comunità astronomica. Infatti, queste particolari proprietà della radiazione elettromagnetica potrebbero permettere di studiare diversi fenomeni astrofisici da un punto di vista completamente nuovo. In questa Tesi vengono presentate alcune possibili applicazioni dei vortici ottici in strumentazione astronomica. In particolare, lo scopo principale di questo lavoro è lo sviluppo di nuove tecniche che permetteranno di migliorare le prestazioni di sistemi ottici. In primo luogo, viene proposto un metodo per aumentare il potere risolutivo di un telescopio limitato dalla diffrazione che prevede l'utilizzo di un fork hologram con una singola dislocazione. I risultati di esperimenti e simulazioni numeriche rivelano che la sovrapposizione dei vortici ottici prodotti da due fasci di luce con una distribuzione d'intensità di Airy mostra già un'evidente asimmetria quando la separazione è di un ordine di grandezza inferiore rispetto al limite posto dal criterio di Rayleigh. Questo risultato è stato ottenuto sia in luce monocromatica, sia in luce bianca. Viene poi presentato il primo esperimento astronomico in cui sono stati prodotti vortici ottici con un fork hologram avente una singola dislocazione posto al piano focale del telescopio Galileo da 122 cm di Asiago. Utilizzando i principi del Lucky Imaging per ridurre gli effetti provocati da condizioni di seeing mediocre, sono state osservate le immagini dei vortici ottici prodotti dalle due componenti principali del sistema multiplo alfa Her, in luce non monocromatica, e dalla stella singola alfa Boo, utilizzando un filtro spaziale a banda stretta. In entrambi i casi, i profili d’intensità dei vortici ottici osservati sono riproducibili con simulazioni numeriche. La sensibilità dell'immagine di un vortice ottico prodotto con un phase modifying device rispetto a spostamenti fuori asse del fascio entrante è confermata da modelli analitici dettagliati e anche da simulazioni numeriche, specialmente nel caso in cui vengano utilizzati elevati valori della cariche topologica l. Questa proprietà potrebbe essere utilizzata per fare misure astrometriche da terra con una precisione che potrebbe competere con quella fornita dalle tecniche standard di astrometria di PSF. La sensibilità rispetto a piccoli spostamenti fuori asse potrebbe anche essere sfruttata per migliorare la correzione dell’aberrazione di tip/tilt del fronte d'onda in un piccolo campo di vista. Viene poi discussa la possibile applicazione di vortici ottici con carica topologica pari nella coronografia ad alto contrasto. In questo caso, l'azione combinata di una spiral phase plate e di un diaframma circolare utilizzato come stop di Lyot permette di annullare totalmente la luce di una stella in asse. Studi teorici indicano che il coronografo a vortici ottici è uno dei pochi che potrebbe realmente permettere l'osservazione diretta di pianeti extrasolari di tipo terrestre. Purtroppo, questa notevole proprietà è fortemente limitata dalle attuali tecniche usate per produrre le spiral phase plate. Nell'ambito di un progetto di costruzione di un coronografo a vortici ottici con l = 2 ottimizzato per lunghezze d'onda visibili, vengono presentati i risultati di simulazioni numeriche ottenuti considerando una spiral phase plate la cui superficie è suddivisa in N livelli discreti. Infine, vengono discusse le procedure sperimentali utilizzate per testare spiral phase plates in PMMA (polimetil-metacrilato).
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Samson, Edward Carlo Copon. "Generating and Manipulating Quantized Vortices in Highly Oblate Bose-Einstein Condensates." Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/228499.

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This dissertation presents several experimental methods that were devised to generate or manipulate quantized vortices in highly oblate dilute-gas Bose-Einstein condensates (BECs). Studies that involve single vortex dynamics, vortex-vortex interactions, and vortex-impurity interactions are essential in developing a deeper understanding of the nature of superfluidity and in particular, superfluid turbulence. In highly oblate systems, vortex dynamics have a two-dimensional (2D) nature and the resulting superfluid characteristics may be substantially different from those in three-dimensional (3D) superfluids. However, there have been remarkably few experimental studies of 2D vortex dynamics in superfluids. Therefore, to study 2D vortex dynamics and interactions, it is necessary to first develop experimental methods that can generate vortices and vortex distributions in nominally 2D systems, such as highly oblate BECs. Four main experiments are discussed in this dissertation. Two of these experiments generate multiple singly quantized vortices in a relatively stochastic manner leading to disordered vortex distributions. From these two vortex methods, the physics of high vorticity and highly disordered systems may be observed and studied in a highly oblate system. These methods may prove useful in studies of 2D quantum turbulence. The other two experiments involve newly developed techniques for controlled generation and manipulation of vortices. One of these methods creates multiply quantized pinned vortices with a control in the generated vorticity. The other method reliably creates a pair of singly quantized vortices of opposite circulation, whose positions can be easily manipulated after creation, such that they can be placed in any location within the BEC. The two techniques may be scalable to higher number of vortices and may prove useful in superfluid dynamics and vortex interactions that require repeatable vortex distributions. Taken together, these tools and methods may be applicable to many further studies of vortex physics in highly oblate BECs.
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Zarzuela, Fernández Ricardo. "Novel quantum phenomena and excitation modes in type-I superconductors and magnetic vortices." Doctoral thesis, Universitat de Barcelona, 2014. http://hdl.handle.net/10803/285263.

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The aim of this thesis was to study quantum phenomena and excitation modes in type-I superconductors and magnetic vortices. The intermediate state in type-I superconductors is characterized by the gradual penetration of magnetic flux and the coexistence of normal and superconducting domains. This thermodynamic phase shows a magnetic irreversibility of topological origin, even in the case of defect-free samples. This irreversibility has been explored in disk-shaped samples made of lead (the prototype of a type-I superconductor) using a magnetic field applied perpendicularly to the disk plane, by means of the measurement of hysteresis cycles at different temperatures, zero-field-cooled and field-cooled magnetization curves at different magnetic fields and magnetic relaxations along the descending branch of the hysteresis cycles. Non-thermal magnetic relaxations have been observed in these samples at low temperatures, which have been attributed to the tunnel effect of normal-superconductor interfaces through pinning energy barriers. A quantum model based on the Caldeira-Leggett theory for dissipative systems have been developed to explain these experimental observations. The interface is described as a 2D elastic manifold that is pinned by a planar defect. The pinning barrier can be controlled by a supercurrent that exerts a force on the interface. The vortex state turns out to be the ground state of magnetic disks for a wide variety of thicknesses and radii. It is characterized by the curling of the magnetization in the plane of the disk, leaving virtually no magnetic ‘charges’. The very weak uncompensated magnetic moment of the disk sticks out of a small area confined to the vortex core. The low-frequency dynamics of the vortex state is characterized by the spiral-like precessional motion of the vortex core as a whole (gyrotropic mode), which can be induced by the application of an in-plane magnetic field. The presence of structural defects in these magnetic disks affects the dynamics of the vortex state, which is indicative of the elastic nature of the vortex core along the axial direction of the disk. It has been studied whether the gyrotropic mode allows spatial dispersion similar to spin waves of a finite wavelength in ferromagnets. The excitation spectrum splits into two branches, one related to the gyrotropic mode with a gap given by the gyrofrequency of the disk and the other related to the existence of an effective mass associated to the vortex core. The magnetic irreversibility of the vortex state has been also explored by means of an experimental protocol analogous to that used in the case of type-I superconductors. Non-thermal magnetic relaxations have been observed again at low temperatures, which is attributed to the tunnel effect of a segment of the vortex core line through pinning barriers. A quantum model based on the Caldeira-Leggett theory for dissipative systems have been developed to explain these experimental observations. The interface is described as a 1D elastic manifold that is pinned by a linear defect. To conclude, the effect of the vortex state on the supercurrent of a Josephson junction has been studied in the case where the non-superconducting layer consists of a magnetic disk with the vortex as the ground state. It has been concluded that the variation of the Josephson current with tiny displacements of the vortex core can be detected experimentally.
El objetivo de esta tesis ha sido estudiar fenómenos cuánticos y modos de excitación en superconductores tipo-I y vórtices magnéticos. La irreversibilidad magnética en muestras de plomo con forma de disco en el estado intermedio ha sido explorada mediante medidas de ciclos de histéresis a diferentes temperaturas, medidas de las curvas de magnetización zero-field-cooled y field-cooled a diferentes campos y relajaciones magnéticas a lo largo de la rama descendiente de los ciclos de histéresis. Se han observado relajaciones magnéticas independientes de la temperatura en estas muestras, las cuales se atribuyen al efecto túnel de las interficies normal-superconductor a través de barreras de anclaje. Un modelo de efecto túnel basado en la teoría de Caldeira-Leggett para sistemas disipativos se ha construido para explicar estas observaciones experimentales, donde la interfície se trata como una variedad 2D elástica que se ancla a defectos planares. La barrera de anclaje se puede controlar mediante la inyección de supercorriente en el sistema. El núcleo del estado vórtice muestra una naturaleza elástica a lo largo de la dirección axial de los discos magnéticos que lo presentan como estado fundamental. Se ha estudiado bajo qué condiciones el modo girótropo es compatible con una dispersión espacial semejante a las ondas de espín de longitud de onda finita presentes en un ferromagneto. El espectro de excitaciones axiales presenta dos ramas bien definidas, una asociada al modo girótropo y la otra originada por la existencia de una masa efectiva asociada al núcleo. También se ha explorado la irreversibilidad magnética del estado vórtice mediante un protocolo análogo al de los superconductores tipo-I. De nuevo se ha observado un comportamiento no térmico a bajas temperaturas en las relajaciones magnéticas, el cual es atribuido al efecto túnel de un segmento del núcleo vorticial a través de las barreras de anclaje. Un modelo de efecto túnel basado en la teoría de Caldeira-Leggett para sistemas disipativos se ha construido para explicar estas observaciones experimentales, donde el núcleo vorticial se trata como una variedad 1D elástica anclada a un defecto lineal. Por último, se ha estudiado cuál sería el efecto del estado vórtice sobre la supercorriente de una unión Josephson si como capa no superconductora se escogiera un disco magnético con este estado fundamental. Se ha concluido que la variación de la corriente Josephson con desplazamientos pequeños del núcleo vorticial es detectable experimentalmente.
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Books on the topic "Reconnection of quantum vortices"

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Thompson, Andrew Mark. Quantum dynamics of two dimensional superfluid vortices. Birmingham: University of Birmingham, 1995.

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Tarantello, Gabriella. Selfdual gauge field vortices: An analytical approach. Boston, Mass: Birkhäuser, 2007.

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Tarantello, Gabriella. Selfdual gauge field vortices: An analytical approach. Boston, Mass: Birkhäuser, 2007.

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Selfdual gauge field vortices: An analytical approach. Boston, Mass: Birkhäuser, 2007.

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Ziltener, Fabian. A quantum Kirwan map: Bubbling and Fredholm theory for symplectic vortices over the plane. Providence, Rhode Island: American Mathematical Society, 2014.

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Seidler, Gerald Todd. Quantum dynamics of vortices in superconductors. 1993.

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Cornwall, John M. Non-Perturbative QCD and Center Vortices. World Scientific Publishing Co Pte Ltd, 2021.

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Oudenaarden, Alexander Van. Quantum Vortices and Quantum Interference Effects in Circuits of Small Tunnel Junctions. Delft Univ Pr, 1998.

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Boldyreva, Liudmila Borisovna. Theory of Spin Vortices in a Physical Vacuum Consisting of Quantum Oscillators. Cambridge Scholars Publisher, 2021.

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Kavokin, Alexey V., Jeremy J. Baumberg, Guillaume Malpuech, and Fabrice P. Laussy. Quantum Fluids of Light. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198782995.003.0010.

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In this chapter, we deal with polaritons as a “quantum fluid of light”, described by variants of the Gross–Pitaevskii equation. We discuss how interactions between flowing polaritons and a defect allow to study their superfluid regime and generate topological defects. Including spin gives rise to an effective magnetic field (polariton spin-orbit coupling) that acts on the topological defects—half-solitons and half-vortices—behaving as effective magnetic monopoles. We describe various techniques to create periodic potentials, that can lead to the formation of polaritonic bands and gaps with a unique flexibility. Special focus is given to topologically nontrivial bands, leading to a polariton topological insulator, based on a polariton graphene analog.
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Book chapters on the topic "Reconnection of quantum vortices"

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Gonzalez, W. D. "Annihilation of Quantum Magnetic Fluxes." In Magnetic Reconnection, 521–38. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-26432-5_13.

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Basdevant, Jean-Louis, and Jean Dalibard. "Quantized Vortices." In The Quantum Mechanics Solver, 235–47. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-13724-3_23.

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Tsubota, Makoto, and Kenichi Kasamatsu. "Quantized Vortices and Quantum Turbulence." In Physics of Quantum Fluids, 283–99. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-37569-9_13.

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Leweke, T., and C. H. K. Williamson. "Long-Wavelength Instability and Reconnection of a Vortex Pair." In IUTAM Symposium on Dynamics of Slender Vortices, 225–34. Dordrecht: Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-011-5042-2_19.

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Smith, C. Morais, B. Ivlev, and G. Blatter. "Quantum Intrinsic Creep of Vortices." In Quantum Dynamics of Submicron Structures, 611–15. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-011-0019-9_49.

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Carroll, J. E. "Entanglement disentangled by spacetime vortices." In Coherence and Quantum Optics VIII, 359–60. Boston, MA: Springer US, 2003. http://dx.doi.org/10.1007/978-1-4419-8907-9_68.

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Wallraff, A., A. Kemp, and A. V. Ustinov. "Quantum Dynamics of Vortices and Vortex Qubits." In Quantum Information Processing, 162–85. Weinheim, FRG: Wiley-VCH Verlag GmbH & Co. KGaA, 2005. http://dx.doi.org/10.1002/3527606009.ch13.

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Vourdas, A., A. Konstadopoulou, and J. M. Hollingworth. "Dual Josephson Phenomena: Interaction of Vortices with Non-Classical Microwaves." In Macroscopic Quantum Coherence and Quantum Computing, 245–52. Boston, MA: Springer US, 2001. http://dx.doi.org/10.1007/978-1-4615-1245-5_25.

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van der Zant, Herre S. J., Lambert J. Geerligs, and Johan E. Mooij. "Vortices and Charges in Tunnel Junction Networks." In Quantum Coherence in Mesoscopic Systems, 511–30. Boston, MA: Springer US, 1991. http://dx.doi.org/10.1007/978-1-4899-3698-1_35.

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Deveaud, Benoit, Gael Nardin, Gabriele Grosso, and Yoan Léger. "Dynamics of Vortices and Dark Solitons in Polariton Superfluids." In Physics of Quantum Fluids, 99–126. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-37569-9_6.

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Conference papers on the topic "Reconnection of quantum vortices"

1

Young, Larry. "A Family of Vortices to Study Axisymmetric Vortex Breakdown and Reconnection." In 25th AIAA Applied Aerodynamics Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2007. http://dx.doi.org/10.2514/6.2007-4447.

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Desyatnikov, Anton S. "Optical Vortices in Discrete Rings." In Quantum Information and Measurement. Washington, D.C.: OSA, 2013. http://dx.doi.org/10.1364/qim.2013.t2a.2.

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O’Holleran, K., M. R. Dennis, and M. J. Padgett. "Optical vortices and topology." In Conference on Coherence and Quantum Optics. Washington, D.C.: OSA, 2007. http://dx.doi.org/10.1364/cqo.2007.cmi33.

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Afanasev, Andrei. "Controlling Atomic Qubits with Optical and Microwave Vortices." In Quantum 2.0. Washington, D.C.: OSA, 2020. http://dx.doi.org/10.1364/quantum.2020.qtu8b.9.

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Desyatnikov, Anton S. "Optical Vortices in Discrete Rings." In Conference on Coherence and Quantum Optics. Washington, D.C.: OSA, 2013. http://dx.doi.org/10.1364/cqo.2013.t2a.2.

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Ostrovskaya, Elena, and Yuri Kivshar. "Matter-wave gap vortices in optical lattices." In International Quantum Electronics Conference. Washington, D.C.: OSA, 2004. http://dx.doi.org/10.1364/iqec.2004.itue3.

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Afanasev, A., C. E. Carlson, and M. Solyanik. "Spin-Asymmetric Absorption of Optical Vortices by Atoms." In Quantum Information and Measurement. Washington, D.C.: OSA, 2017. http://dx.doi.org/10.1364/qim.2017.qt6a.1.

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Wisniacki, D. A., E. R. Pujals, and F. Borondo. "Vortices and chaos in the quantum fluid." In FRONTIERS OF FUNDAMENTAL PHYSICS: Eighth International Symposium FFP8. AIP, 2007. http://dx.doi.org/10.1063/1.2736998.

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Pinheiro, A. R. C., C. E. R. Souza, D. P. Caetano, J. A. O. Huguenin, A. G. M. Schmidt, and A. Z. Khoury. "Playing a quantum game on polarization vortices." In CLEO: QELS_Fundamental Science. Washington, D.C.: OSA, 2013. http://dx.doi.org/10.1364/cleo_qels.2013.qw1c.5.

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Vahala, George, Jeffrey Yepez, and Linda Vahala. "Quantum lattice gas algorithm for quantum turbulence and vortex reconnection in the Gross-Pitaevskii equation." In SPIE Defense and Security Symposium, edited by Eric J. Donkor, Andrew R. Pirich, and Howard E. Brandt. SPIE, 2008. http://dx.doi.org/10.1117/12.777722.

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Reports on the topic "Reconnection of quantum vortices"

1

Stenzel, R. L. Vortices, Reconnection and Turbulence in High Electron-Beta Plasmas. Office of Scientific and Technical Information (OSTI), August 2004. http://dx.doi.org/10.2172/829968.

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Yepez, Jeffrey. Kappa-3 Superfluid Spectrum of Highly Curved Interacting Quantum Vortices. Fort Belvoir, VA: Defense Technical Information Center, February 2010. http://dx.doi.org/10.21236/ada523529.

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