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Satellite rings and normal modes in rotating clouds of ultra cold atoms  [PDF]
J. D. Rodrigues,J. T. Mendon?a,J. A. Rodrigues
Physics , 2014,
Abstract: The multiple scattering of light in a gas of ultra cold atoms is responsible for many exciting features observed in magneto-optical traps including the collective behavior forced by a Coulomb like potential. This field also induces plasma like phenomena in the cloud which allows the treatment of the system as a one component trapped plasma. With a fluid description and casting the thermodynamical behavior in the form of a polytropic equation of state we investigate the equilibrium profiles of rotating clouds and its dependence on the experiment characteristics. Numerical solutions predict the formation of stable orbital modes both in rotating and non rotating clouds. We also investigate the normal modes on such rotating systems.
Vortex Rings in Fast Rotating Bose-Einstein Condensates  [PDF]
Nicolas Rougerie
Mathematics , 2010, DOI: 10.1007/s00205-011-0447-6
Abstract: When Bose-Eintein condensates are rotated sufficiently fast, a giant vortex phase appears, that is the condensate becomes annular with no vortices in the bulk but a macroscopic phase circulation around the central hole. In a former paper [M. Correggi, N. Rougerie, J. Yngvason, {\it arXiv:1005.0686}] we have studied this phenomenon by minimizing the two dimensional Gross-Pitaevskii energy on the unit disc. In particular we computed an upper bound to the critical speed for the transition to the giant vortex phase. In this paper we confirm that this upper bound is optimal by proving that if the rotation speed is taken slightly below the threshold there are vortices in the condensate. We prove that they gather along a particular circle on which they are evenly distributed. This is done by providing new upper and lower bounds to the GP energy.
The phase diagram of two-dimensional fast-rotating ultra-cold fermionic atoms near unitarity  [PDF]
Predrag Nikolic
Physics , 2009, DOI: 10.1103/PhysRevA.81.023601
Abstract: By analyzing vortex lattices, re-entrant Cooper pairing and Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) states in a single theoretical framework we explore how vortices and spin textures join to protect superconductivity against large magnetic fields. We use a rapidly rotating ultra-cold gas of fermionic atoms near unitarity as a model system amenable to experimental exploration, and discover a hierarchy of spin-polarized and FFLO phases in which a metal or a band-insulator of unpaired particles coexists with a spatially modulated superfluid hosting a vortex lattice. Quantum fluctuations can transform these phases into strongly correlated "vortex liquid" metals and insulators respectively. We argue that vortex lattices significantly enhance the stability of FFLO states and discuss prospects for observing these states in cold atom experiments.
Generic occurrence of rings in rotating systems  [PDF]
L. Benet,T. H. Seligman
Physics , 2000, DOI: 10.1016/S0375-9601(00)00500-4
Abstract: In rotating scattering systems, the generic saddle-center scenario leads to stable islands in phase space. Non-interacting particles whose initial conditions are defined in such islands will be trapped and form rotating rings. This result is generic and also holds for systems quite different from planetary rings.
Anyonic Excitations in Fast Rotating Bose Gases Revisited  [PDF]
A. Lakhoua,M. Lassaut,T. Masson,J. C. Wallet
Physics , 2005, DOI: 10.1103/PhysRevA.73.023614
Abstract: The role of anyonic excitations in fast rotating harmonically trapped Bose gases in a fractional Quantum Hall state is examined. Standard Chern-Simons anyons as well as "non standard" anyons obtained from a statistical interaction having Maxwell-Chern-Simons dynamics and suitable non minimal coupling to matter are considered. Their respective ability to stabilize attractive Bose gases under fast rotation in the thermodynamical limit is studied. Stability can be obtained for standard anyons while for non standard anyons, stability requires that the range of the corresponding statistical interaction does not exceed the typical wavelenght of the atoms.
Anyonic Excitations in Fast Rotating Bose Gases  [PDF]
J. C. Wallet
Physics , 2005,
Abstract: The role of anyonic excitations in fast rotating harmonically trapped Bose gases in a fractional Quantum Hall State is examined. Standard Chern-Simons anyons as well as "non standard" anyons obtained from a statistical interaction having Maxwell-Chern-Simons dynamics and suitable non minimal coupling to matter are considered. Their respective ability to stabilize attractive Bose gases under fast rotation in the thermodynamical limit is studied. Stability can be obtained for standard anyons while for non standard anyons, stability requires that the range of the corresponding statistical interaction does not exceed the typical wavelength for the atoms.
Gravitational wave asteroseismology with fast rotating neutron stars  [PDF]
Erich Gaertig,Kostas D. Kokkotas
Physics , 2010, DOI: 10.1103/PhysRevD.83.064031
Abstract: We investigate damping and growth times of the f-mode for rapidly rotating stars and a variety of different polytropic equations of state in the Cowling approximation. We discuss the differences in the eigenfunctions of co- and counterrotating modes and compute the damping times of the f-mode for several EoS and all rotation rates up to the Kepler-limit. This is the first study of the damping/growth time of this type of oscillations for fast rotating neutron stars in a general relativistic framework. We use these frequencies and damping/growth times to create robust empirical formulae which can be used for gravitational wave asteroseismology. The estimation of the damping/growth time is based on the quadrupole formula and our results agree very well with Newtonian ones in the appropriate limit.
Uniformly Rotating Rings in General Relativity  [PDF]
Thomas Fischer,Stefan Horatschek,Marcus Ansorg
Physics , 2005, DOI: 10.1111/j.1365-2966.2005.09629.x
Abstract: In this paper, we discuss general relativistic, self-gravitating and uniformly rotating perfect fluid bodies with a toroidal topology (without central object). For the equations of state describing the fluid matter we consider polytropic as well as completely degenerate, perfect Fermi gas models. We find that the corresponding configurations possess similar properties to the homogeneous relativistic Dyson rings. On the one hand, there exists no limit to the mass for a given maximal mass-density inside the body. On the other hand, each model permits a quasistationary transition to the extreme Kerr black hole.
A Roche Model for Uniformly Rotating Rings  [PDF]
Stefan Horatschek,David Petroff
Physics , 2008, DOI: 10.1111/j.1365-2966.2008.14122.x
Abstract: A Roche model for describing uniformly rotating rings is presented and the results are compared with numerical solutions to the full problem for polytropic rings. In the thin ring limit, the surfaces of constant pressure including the surface of the ring itself are given in analytic terms, even in the mass-shedding case.
Fast quantum gates for neutral atoms  [PDF]
D. Jaksch,J. I. Cirac,P. Zoller,S. L. Rolston,R. Cote,M. D. Lukin
Physics , 2000, DOI: 10.1103/PhysRevLett.85.2208
Abstract: We propose several schemes for implementing a fast two-qubit quantum gate for neutral atoms with the gate operation time much faster than the time scales associated with the external motion of the atoms in the trapping potential. In our example, the large interaction energy required to perform fast gate operations is provided by the dipole-dipole interaction of atoms excited to low-lying Rydberg states in constant electric fields. A detailed analysis of imperfections of the gate operation is given.
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