Density functional theory of vortex lattice melting in layered superconductors: a mean-field--substrate approach

We study the melting of the pancake vortex lattice in a layered superconductor in the limit of vanishing Josephson coupling. Our approach combines the methodology of a recently proposed mean-field substrate model for such systems with the classical density functional theory of freezing. We derive a free-energy functional in terms of a scalar order-parameter profile and use it to derive a simple formula describing the temperature dependence of the melting field. Our theoretical predictions are in good agreement with simulation data. The theoretical framework proposed is thermodynamically consistent and thus capable of describing the negative magnetization jump obtained in experiments. Such consistency is demonstrated by showing the equivalence of our expression for the density discontinuity at the transition with the corresponding Clausius-Clapeyron relation.Comment: 11 pages, 4 figure

Decoupling Transition I. Flux Lattices in Pure Layered Superconductors

We study the decoupling transition of flux lattices in a layered superconductors at which the Josephson coupling J is renormalized to zero. We identify the order parameter and related correlations; the latter are shown to decay as a power law in the decoupled phase. Within 2nd order renormalization group we find that the transition is always continuous, in contrast with results of the self consistent harmonic approximation. The critical temperature for weak J is ~1/B, where B is the magnetic field, while for strong J it is~1/sqrt{B} and is strongly enhanced. We show that renormaliztion group can be used to evaluate the Josephson plasma frequency and find that for weak J it is~1/BT^2 in the decoupled phase.Comment: 14 pages, 5 figures. New sections III, V. Companion to following article on "Decoupling and Depinning II: Flux lattices in disordered layered superconductors

Bell's inequality test with time-delayed two-particle correlations

Adopting the frame of mesoscopic physics, we describe a Bell type experiment involving time-delayed two-particle correlation measurements. The indistinguishability of quantum particles results in a specific interference between different trajectories. We show how the non-locality in the time-delayed correlations due to the indistinguishability of the quantum particles manifests itself in the violation of a Bell inequality, where the degree of violation is related to the accuracy of the measurement. We demonstrate how the interrelation between the orbital- and the spin exchange symmetry can by exploited to infer knowledge on spin-entanglement from a measurement of orbital entanglement.Comment: 8 pages, 4 figure

Research and development of a vortex valve for flow modulation of a 16-percent aluminized 5500 deg F propellant gas

Vortex valve for hot gas flow modulation in secondary injection thrust vector control syste

Zeeman and Orbital Limiting Fields: Separated Spin and Charge Degrees of Freedom in Cuprate Superconductors

Recent in-plane thermal (Nernst) and interlayer (tunnelling) transport experiments in Bi$_2$Sr$_2$CaCu$_2$O$_{8+y}$ high temperature superconductors report hugely different limiting magnetic fields. Based on pairing (and the uncertainty principle) combined with the definitions of the Zeeman energy and the magnetic length, we show that in the underdoped regime both fields convert to the same (normal state) pseudogap energy scale $T^*$ upon transformation as orbital and spin (Zeeman) critical fields, respectively. We reconcile these seemingly disparate findings invoking separated spin and charge degrees of freedom residing in different regions of a truncated Fermi surface.Comment: 4 pages, 3 figures; accepted for publication in Phys. Rev. B (Rapid Comm.

Research and development of a vortex valve controlled hot gas /5500 deg F/ secondary injection thrust vector control system

Performance of vortex valve controlled secondary injection thrust vector system for solid propellant rocket motor contro

Characteristics of First-Order Vortex Lattice Melting: Jumps in Entropy and Magnetization

We derive expressions for the jumps in entropy and magnetization characterizing the first-order melting transition of a flux line lattice. In our analysis we account for the temperature dependence of the Landau parameters and make use of the proper shape of the melting line as determined by the relative importance of electromagnetic and Josephson interactions. The results agree well with experiments on anisotropic Y$_1$Ba$_2$Cu$_3$O$_{7-\delta}$ and layered Bi$_2$Sr$_2$Ca$_1$Cu$_2$O$_8$ materials and reaffirm the validity of the London model.Comment: 4 pages. We have restructured the paper to emphasize that in the London scaling regime (appropriate for YBCO) our results are essentially exact. We have also emphasized that a major controversy over the relevance of the London model to describe VL melting has been settled by this wor

Absence of a structural glass phase in a monoatomic model liquid predicted to undergo an ideal glass transition

We study numerically a monodisperse model of interacting classical particles predicted to exhibit a static liquid-glass transition. Using a dynamical Monte Carlo method we show that the model does not freeze into a glassy phase at low temperatures. Instead, depending on the choice of the hard-core radius for the particles the system either collapses trivially or a polycrystalline hexagonal structure emerges.Comment: 4 pages, 4 figures, minor changes in introduction and conclusions, additional reference

Commensurate-incommensurate transition of cold atoms in an optical lattice

An atomic gas subject to a commensurate periodic potential generated by an optical lattice undergoes a superfluid--Mott insulator transition. Confining a strongly interacting gas to one dimension generates an instability where an arbitrary weak potential is sufficient to pin the atoms into the Mott state; here, we derive the corresponding phase diagram. The commensurate pinned state may be detected via its finite excitation gap and the Bragg peaks in the static structure factor.Comment: 4 pages, 2 figure