Precursory Cooper flow in ultralow-temperature superconductors

Superconductivity at low temperature—observed in lithium and bismuth, as well as in various low-density superconductors—calls for the development of reliable theoretical and experimental tools for predicting ultralow critical temperatures Tc of Cooper instability in a system demonstrating simply normal Fermi liquid behavior in a broad range of temperatures below the Fermi energy TF. Equally important are controlled predictions of stability in a given Cooper channel. We identify such a protocol within the paradigm of precursory Cooper flow—a universal ansatz describing logarithmically slow temperature evolution of the linear response of the normal state to the pair-creating perturbation. Applying this framework to the two-dimensional uniform electron gas, we reveal a series of exotic superconducting states, pushing controlled theoretical predictions of Tc to the unprecedentedly low scale of 10−100Tf

Superclimbing modes in transverse quantum fluids: signature statistical and dynamical features

Superclimbing modes are hallmark degrees of freedom of transverse quantum fluids describing wide superfluid one-dimensional interfaces and/or edges with negligible Peierls barrier. We report the first direct numeric evidence of quantum shape fluctuations -- caused by superclimbing modes -- in simple lattice models, as well as at the free edge of an incomplete solid monolayer of $^4$He adsorbed on graphite. Our data unambiguously reveals the defining feature of the superclimbing modes -- canonical conjugation of the edge displacement field to the field of superfluid phase -- and its unexpected implication, i.e., that superfluid stiffness can be inferred from density snapshots.11 pages, 9 figure

Fermi Blockade of the Strong Electron-Phonon Interaction in Modelled Optimally Doped High Temperature Superconductors

We study how manifestations of strong electron-phonon interaction depend on the carrier concentration by solving the two-dimensional Holstein model for the spin-polarized fermions using an approximation free bold-line diagrammatic Monte Carlo method. We show that the strong electron-phonon interaction, obviously present at very small Fermion concentration, is masked by the Fermi blockade effects and Migdal\u27s theorem to the extent that it manifests itself as moderate one at large carriers densities. Suppression of strong electron-phonon interaction fingerprints is in agreement with experimental observations in doped high temperature superconductors

Implementation of the Bin Hierarchy Method for Restoring a Smooth Function from a Sampled Histogram

We present BHM, a tool for restoring a smooth function from a sampled histogram using the bin hierarchy method. The theoretical background of the method is presented in [1]. The code automatically generates a smooth polynomial spline with the minimal acceptable number of knots from the input data. It works universally for any sufficiently regular shaped distribution and any level of data quality, requiring almost no external parameter specification. It is particularly useful for large-scale numerical data analysis. This paper explains the details of the implementation and the use of the program

Superconducting Transition Temperature of the Bose One-Component Plasma

We present results of numerically exact simulations of the Bose one-component plasma, i.e., a Bose gas with pairwise Coulomb interactions among particles and a uniform neutralizing background. We compute the superconducting transition temperature for a wide range of densities, in two and three dimensions, for both continuous and lattice versions of the model. The Coulomb potential causes the weakly interacting limit to be approached at high density, but gives rise to no qualitatively different behavior, vis-à-vis the superfluid transition, with respect to short-ranged interactions. Our results are of direct relevance to quantitative studies of bipolaron mechanisms of (high-temperature) superconductivity