Special Issue "Fluctuations and Highly Non-linear Phenomena in Superfluids and Superconductors"

A special issue of Condensed Matter (ISSN 2410-3896).

Deadline for manuscript submissions: closed (31 January 2019).

Special Issue Editors

Guest Editor
Prof. Dr. Luca Dell'Anna Website E-Mail
Dipartimento di Fisica e Astronomia "Galileo Galilei", Università degli Studi di Padova, Via F. Marzolo 8, I-35131 Padova, Italy
Interests: ultracold atoms; disordered systems; mesoscopic physics
Guest Editor
Prof. Dr. Luca Salasnich Website E-Mail
Department of Physics and Astronomy "Galileo Galilei", University of Padova, Via Marzolo 8, 35131 Padova, Italy
Phone: +39 049 827 7132
Interests: Bose-Einstein condensation; Bose-Einstein condensation; ultracold atoms; quantum statistical physics
Guest Editor
Prof. Dr. Andrea Perali Website E-Mail
Università di Camerino, Scuola del Farmaco e Divisione di Fisica, Edificio di Fisica, Via Madonna delle Carceri 9, 62032 Camerino (MC), Italy
Interests: high-Tc superconductivity (theory and phenomenology), multiband superconductivity, quantum size effects and shape resonances in superconductors, nanoscale superconductors, superconducting heterostructures, BCS-BEC crossover, pseudogap, superconducting fluctuations, ultracold fermions: superfluidity and BCS-BEC crossover, electron–hole superfluidity

Special Issue Information

Dear Colleagues,

This Special Issue of Condensed Matter is dedicated to charge, spin, and pair fluctuations and other highly non-linear phenomena in novel superfluid and superconducting systems.

Among the main topics of the Special Issue is the study of fluctuations and BCS-BEC crossover phenomena in low dimensional systems. Very recently, the BCS-BEC crossover has been realized in quasi two-dimensional (2D) ultracold gases made of alkali-metal atoms. Contrary to the 3D case, mean-field theories are completely unreliable for the study of strongly-interacting superfluid fermions in two dimensions because of the huge increase of quantum fluctuations. The 2D BCS-BEC crossover is also interesting for high-Tc superconductivity where the phase diagram of cuprate superconductors can be interpreted in terms of a BCS-BEC crossover as doping is varied. The critical temperature Tc has a wide fluctuation region with pseudo-gap effects not yet fully understood.

Another hot topic of the Special Issue is multiband and multigap superconductors, which have demonstrated the potential for realizing novel coherent quantum phenomena and to control system parameters to enhance the superconducting critical temperature and the pairing energy gaps. Nanostructuring of bulk superconductors in the form of nanofilms, nanostripes, and nanoclusters, or introducing controlled non homogeneities has shown to be able to induce multi-gap and multiband superconductivity and superconducting shape resonances. Very recently, it has been suggested that iron-based superconductors have composite superconductivity, consisting of strong-coupling BEC in the electron band and weak-coupling BCS-like superconductivity in the hole band. Indeed, the intermediate crossover regime between BCS and BEC superconductivity is now considered as one of the most promising regimes in the search for high-Tc superconductivity.

Main Topics:

  • Fluctuations and BCS-BEC crossover phenomena in low dimensional systems
  • Hybrid systems, superconductivity at the interfaces, and coexistence of phases
  • Highly non-linear phenomena: Josephson and Andreev effects, topological defects, skyrmions and solitons, vortex states
  • Novel phenomena in multicomponent/multigap superconductors and superfluids
  • Innovative numerical methods for superfluids and superconductors

Prof. Luca Dell'Anna
Prof. Luca Salasnich
Prof. Andrea Perali
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Condensed Matter is an international peer-reviewed open access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (5 papers)

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Research

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Open AccessArticle
Effect of Phase Errors on a Quantum Control Protocol Using Fast Oscillations
Condens. Matter 2019, 4(1), 34; https://doi.org/10.3390/condmat4010034 - 22 Mar 2019
Cited by 1
Abstract
It has been recently shown that fast oscillating control fields can be used to speed up an otherwise slow adiabatic process, making the system always follow an instantaneous eigenvector closely. In applying this method though, one typically assumes perfect phase relations among the [...] Read more.
It has been recently shown that fast oscillating control fields can be used to speed up an otherwise slow adiabatic process, making the system always follow an instantaneous eigenvector closely. In applying this method though, one typically assumes perfect phase relations among the control fields. In this work, we discuss the effect of potential static phase errors. We show that the latter can in some cases produce higher fidelities, leading to an unexpected improvement of the method. This is shown numerically and explained via a perturbative expansion of the error produced by the control strategy. When high-precision phase control is accessible, the results suggest that the phases of the control field can be used as free parameters whose optimization can be beneficial for the control protocol. Full article
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Open AccessArticle
Zero-Temperature Equation of State of a Two-Dimensional Bosonic Quantum Fluid with Finite-Range Interaction
Condens. Matter 2019, 4(1), 20; https://doi.org/10.3390/condmat4010020 - 03 Feb 2019
Cited by 1
Abstract
We derive the two-dimensional equation of state for a bosonic system of ultracold atoms interacting with a finite-range effective interaction. Within a functional integration approach, we employ a hydrodynamic parameterization of the bosonic field to calculate the superfluid equations of motion and the [...] Read more.
We derive the two-dimensional equation of state for a bosonic system of ultracold atoms interacting with a finite-range effective interaction. Within a functional integration approach, we employ a hydrodynamic parameterization of the bosonic field to calculate the superfluid equations of motion and the zero-temperature pressure. The ultraviolet divergences, naturally arising from the finite-range interaction, are regularized with an improved dimensional regularization technique. Full article
Open AccessArticle
Many-Body Physics of Low-Density Dipolar Bosons in Box Potentials
Condens. Matter 2019, 4(1), 17; https://doi.org/10.3390/condmat4010017 - 22 Jan 2019
Cited by 1
Abstract
Crystallization is a generic phenomenon in classical and quantum mechanics arising in a variety of physical systems. In this work, we focus on a specific platform, ultracold dipolar bosons, which can be realized in experiments with dilute gases. We reviewed the relevant ingredients [...] Read more.
Crystallization is a generic phenomenon in classical and quantum mechanics arising in a variety of physical systems. In this work, we focus on a specific platform, ultracold dipolar bosons, which can be realized in experiments with dilute gases. We reviewed the relevant ingredients leading to crystallization, namely the interplay of contact and dipole–dipole interactions and system density, as well as the numerical algorithm employed. We characterized the many-body phases investigating correlations and superfluidity. Full article
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Open AccessArticle
Impact of Lattice Vibrations on the Dynamics of a Spinor Atom-Optics Kicked Rotor
Condens. Matter 2019, 4(1), 10; https://doi.org/10.3390/condmat4010010 - 14 Jan 2019
Abstract
We investigate the effect of amplitude and phase noise on the dynamics of a discrete-time quantum walk and its related evolution. Our findings underline the robustness of the motion with respect to these noise sources, and can explain the stability of quantum walks [...] Read more.
We investigate the effect of amplitude and phase noise on the dynamics of a discrete-time quantum walk and its related evolution. Our findings underline the robustness of the motion with respect to these noise sources, and can explain the stability of quantum walks that has recently been observed experimentally. This opens the road to measure topological properties of an atom-optics double kicked rotor with an additional internal spin degree of freedom. Full article
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Review

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Open AccessReview
The Variational Reduction for Low-Dimensional Fermi Gases and Bose–Fermi Mixtures: A Brief Review
Condens. Matter 2019, 4(1), 22; https://doi.org/10.3390/condmat4010022 - 10 Feb 2019
Abstract
We present a summary of some recent theoretical results for matter-wave patterns in Fermi and Bose–Fermi degenerate gases, obtained in the framework of the quasi-mean-field approximation. We perform a dimensional reduction from the three-dimensional (3D) equations of motion to 2D and 1D effective [...] Read more.
We present a summary of some recent theoretical results for matter-wave patterns in Fermi and Bose–Fermi degenerate gases, obtained in the framework of the quasi-mean-field approximation. We perform a dimensional reduction from the three-dimensional (3D) equations of motion to 2D and 1D effective equations. In both cases, comparison of the low-dimensional reductions to the full model is performed, showing very good agreement for ground-state solutions. Some complex dynamical regimes are reported too for the corresponding 1D systems. Full article
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