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Article
Open AccessLinear response of a superfluid Fermi gas inside its pair-breaking continuum
We study the signatures of the collective modes of a superfluid Fermi gas in its linear response functions for the order-parameter and density fluctuations in the Random Phase Approximation (RPA). We show that...
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Article
Superconductivity in SrTiO3: Dielectric Function Method for Non-Parabolic Bands
The dielectric function method for superconductivity has been applied to SrTiO3 accounting for the non-parabolic dispersion of charge carriers in the conduction band and for the dispersion of optical phonons base...
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Article
Anderson–Bogoliubov Collective Excitations in Superfluid Fermi Gases at Nonzero Temperatures
The Anderson–Bogoliubov branch of collective excitations in a condensed Fermi gas is treated using the effective bosonic action of Gaussian pair fluctuations. The spectra of collective excitations are treated ...
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Article
Radial vortex core oscillations in Bose-Einstein condensates
Dilute ultracold quantum gases form an ideal and highly tunable system in which superfluidity can be studied. Recently quantum turbulence in Bose-Einstein condensates was reported [PRL 103, 045310 (2009)], openi...
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Article
The Creation of Long-Lived Multielectron Bubbles in Superfluid Helium
Multielectron bubbles (MEBs) in liquid helium were first observed in the late 1970s, but their properties have never been explored experimentally due to their short lifetimes. MEBs in liquid helium are predict...
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Article
Multiband Superconductivity Due to the Electron–LO–Phonon Interaction in Strontium Titanate and on a SrTiO3/LaAlO3 Interface
In strontium titanate, the Fröhlich electron – LO-phonon interaction dominates the electron response and can also provide superconductivity. Because of high LO-phonon frequencies in SrTiO3, the superconducting sy...
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Article
Contact Potential Instability in the Path-Integral Description of Itinerant Ferromagnetism
It has long been predicted that a two-component non-localized Fermi gas will exhibit spontaneous polarization for sufficiently strong repulsive interactions, a phenomenon which is called itinerant ferromagneti...
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Article
Vortex–Antivortex Unbinding in Inhomogeneous 2D Atomic Condensates
The breakdown of superfluidity in a two-dimensional Bose gas is linked with the unbinding of vortex–antivortex pairs, which has been observed directly in a recent experiment with trapped atomic gases. The phen...
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Article
Thermodynamic Functions for Superfluid Fermions in Two Dimensions
The parameters of state for interacting ultracold fermionic atoms with s-wave pairing in 2D are calculated as a function of temperature in the superfluid, pseudogap and normal states. The pseudogap pairing temper...
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Article
Weak coupling many-polaron description of ultracold bosonic impurities in a condensate
The weak coupling many-polaron formalism is applied to ultracold bosonic impurities in a Bose-Einstein condensate. This formalism allows calculating the ground state and response properties. We apply this to c...
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Article
Pair Excitations and Parameters of State of Imbalanced Fermi Gases at Finite Temperatures
The spectra of low-lying pair excitations for an imbalanced two-component superfluid Fermi gas are analytically derived within the path-integral formalism taking into account Gaussian fluctuations about the sa...
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Article
Strong coupling treatment of the polaronic system consisting of an impurity in a condensate
The strong coupling treatment of the Fröhlich-type polaronic system, based on a canonical transformation and a standard Landau-Pekar type variational wave function, is applied to the polaronic system consistin...
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Article
Polaronic Properties of an Ion in a Bose-Einstein Condensate in the Strong-Coupling Limit
Cold atoms can be used to model the Fröhlich polaron Hamiltonian using an impurity in a condensate. To probe the strong-coupling regime (which remains elusive in the solid state) charged impurities can be bett...
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Article
Fluctuation Spectral Functions and Phase Transitions for Cold Fermi Gases in 2D
We study cold fermions in 2D that are interacting through the s-wave contact potential, using the path-integral formalism. The phase transitions are investigated using the joint solution of the gap and number equ...
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Article
Generalized pricing formulas for stochastic volatility jump diffusion models applied to the exponential Vasicek model
Path integral techniques for the pricing of financial options are mostly based on models that can be recast in terms of a Fokker-Planck differential equation and that, consequently, neglect jumps and only desc...
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Article
Thermodynamic Quantities of Imbalanced 2D Fermi Gases Near the Berezinskii-Kosterlitz-Thouless Transition
We investigate the effects of imbalance on the two-dimensional Berezinskii-Kosterlitz-Thouless superfluid transition for a Fermi gas in a parabolic trap. Thermodynamic parameters of the Fermi gas are determine...
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Article
Flow and Critical Velocity of an Imbalanced Fermi Gas through an Optical Potential
Optical lattices offer the possibility to investigate the superfluid properties of both Bose condensates and Fermionic superfluid gases. When a population imbalance is present in a Fermi mixture, this leads t...
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Article
Critical Radius and Magnetic Field for Vortex Nucleation on a Superconducting Spherical Surface
Spherical, two-dimensional electron systems are realized in nanoshells and multielectron bubbles in helium. In this contribution, we investigate the superconducting state of such shells using a variational Gi...
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Article
Magnetohydrodynamic properties of incompressible Meissner fluids
We consider a superconducting material that exists in the liquid state, more precisely, in which the Meissner-Ochsenfeld effect persists in the liquid state. First, we investigate how the shape of such a hypot...
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Article
Magnetic Properties of a Multielectron Bubble in Liquid Helium
Multielectron bubbles in liquid helium contain a spherical two-dimensional shell of electrons at the bubble surface. We investigate the properties of this electron gas when the bubble is placed in a homogeneou...
