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Phase Transitions In A Three Dimensional U(1)×U(1) Lattice London Superconductor: Metallic Superfluid And Charge-4e Superconducting States, Egil V. Herland, Egor Babaev, Asle Sudbø
Phase Transitions In A Three Dimensional U(1)×U(1) Lattice London Superconductor: Metallic Superfluid And Charge-4e Superconducting States, Egil V. Herland, Egor Babaev, Asle Sudbø
Physics Department Faculty Publication Series
We consider a three dimensional lattice U(1)×U(1) and [U(1)]N superconductors in the London limit with individually conserved condensates. The U(1)×U(1) problem, generically, has two types of intercomponent interactions of different characters. First, the condensates are interacting via a minimal coupling to the same fluctuating gauge field. A second type of coupling is the direct dissipationless drag represented by a local intercomponent current-current coupling term in the free-energy functional. In this work, we present a study of the phase diagram of a U(1)×U(1) superconductor which includes both of these interactions. We study phase transitions and two types of competing paired phases …
Type-1.5 Superconductivity In Two-Band Systems, Egor Babaev, Johan Carlstrom
Type-1.5 Superconductivity In Two-Band Systems, Egor Babaev, Johan Carlstrom
Physics Department Faculty Publication Series
In the usual Ginzburg–Landau theory the critical value of Ginzburg–Landau parameter View the MathML source separates regimes of type-I and type-II superconductivity. The latter regime possess thermodynamically stable vortex excitations which interact with each other repulsively and tend to form vortex lattices. It was shown in [5] that this dichotomy in broken in U(1) × U(1) Ginzburg–Landau models which possess a distinct phase with vortex excitations which interact attractively at large length scales and repulsively at shorter distances. Here we discuss the influence of the Josephson coupling and that similar kind of superconductivity can also arise for entirely different reasons …
Berezinskii-Kosterlitz-Thouless Transition In Two-Dimensional Dipole Systems, A Filinov, N Prokof'ev, M Bonitz
Berezinskii-Kosterlitz-Thouless Transition In Two-Dimensional Dipole Systems, A Filinov, N Prokof'ev, M Bonitz
Physics Department Faculty Publication Series
The superfluid to normal fluid transition of dipolar bosons in two dimensions is studied in a broad density range by using path integral Monte Carlo simulations and summarized in the phase diagram. While at low densities we find good agreement with the universal results depending only on the scattering length as, at moderate and high densities the transition temperature is strongly affected by interactions and the excitation spectrum of quasiparticles. The results are expected to be of relevance to dipolar atomic and molecular systems and indirect excitons in quantum wells.
Worm Algorithm For Problems Of Quantum And Classical Statistics, Nikolai Prokof'ev, Boris Svistunov
Worm Algorithm For Problems Of Quantum And Classical Statistics, Nikolai Prokof'ev, Boris Svistunov
Physics Department Faculty Publication Series
This is a chapter of the multi-author book “Understanding Quantum Phase Transitions,” edited by Lincoln Carr and published by Taylor & Francis. In this chapter, we give a general introduction to the worm algorithm and present important results highlighting the power of the approach.
Topological Multicritical Point In The Phase Diagram Of The Toric Code Model And Three-Dimensional Lattice Gauge Higgs Model, I Tupitsyn, A Kitaev, Nikolai Prokof'ev, P.C.E Stamp
Topological Multicritical Point In The Phase Diagram Of The Toric Code Model And Three-Dimensional Lattice Gauge Higgs Model, I Tupitsyn, A Kitaev, Nikolai Prokof'ev, P.C.E Stamp
Physics Department Faculty Publication Series
We construct a mapping between the two-dimensional toric code model in external magnetic fields, hz and hx, and the three-dimensional classical Ising system with plaquette interactions, which is equivalent to the three-dimensional Z2 gauge Higgs model with anisotropy between the imaginary time and spatial directions. The isotropic limit of the latter model was studied using Monte Carlo simulations on large (up to 603) lattices in order to determine the stability of the topological phase against generic magnetic field perturbations and to resolve fine details of the phase diagram. We find that the topological phase is bounded by second-order transition lines, …
Diagrammatic Monte Carlo For Correlated Fermions, E Kozik, K Houcke, E Gull, L. Pollet, Nikolai Prokof'ev, Boris Svistunov, M Troyer
Diagrammatic Monte Carlo For Correlated Fermions, E Kozik, K Houcke, E Gull, L. Pollet, Nikolai Prokof'ev, Boris Svistunov, M Troyer
Physics Department Faculty Publication Series
We show that Monte Carlo sampling of the Feynman diagrammatic series (DiagMC) can be used for tackling hard fermionic quantum many-body problems in the thermodynamic limit by presenting accurate results for the repulsive Hubbard model in the correlated Fermi liquid regime. Sampling Feynman's diagrammatic series for the single-particle self-energy, we can study moderate values of the on-site repulsion (U/t~4) and temperatures down to T/t=1/40. We compare our results with high-temperature series expansions and with single-site and cluster dynamical mean-field theory.
Criticality In Trapped Atomic Systems, L Pollet, Nikolai Prokof'ev, Boris Svistunov
Criticality In Trapped Atomic Systems, L Pollet, Nikolai Prokof'ev, Boris Svistunov
Physics Department Faculty Publication Series
We discuss generic limits posed by the trap in atomic systems on the accurate determination of critical parameters for second-order phase transitions, from which we deduce optimal protocols to extract them. We show that under current experimental conditions the in situ density profiles are barely suitable for an accurate study of critical points in the strongly correlated regime. Contrary to recent claims, the proper analysis of time-of-fight images yields critical parameters accurately.
An Extended Kerr–Schild Ansatz, Benjamin Ett, David Kastor
An Extended Kerr–Schild Ansatz, Benjamin Ett, David Kastor
Physics Department Faculty Publication Series
We present an analysis of the vacuum Einstein equations for a recently proposed extension of the Kerr–Schild ansatz that includes a spacelike vector field as well as the usual Kerr–Schild null vector. We show that many, although not all, of the simplifications that occur in the Kerr–Schild case continue to hold for the extended ansatz. In particular, we find a simple set of sufficient conditions on the vectors such that the vacuum field equations truncate beyond quadratic order in an expansion around a general vacuum background solution. We extend our analysis to the electrovac case with a related ansatz for …