BCS-BEC Crossover

  title={BCS-BEC Crossover},
  author={Klaus Sengstock},
  journal={Peking University-World Scientific Advanced Physics Series},
  • K. Sengstock
  • Published 1 November 2018
  • Physics
  • Peking University-World Scientific Advanced Physics Series
A crossover usually refers in physics to a situation where the system parameters change from one regime to another. For instance, the interactions in a system may change from weak to strong. Or, there can be a dimensional crossover from e.g. one to two-dimensional configuration. There can be also crossovers between two qualitatively di↵erent many-body states. In general, the word crossover refers to smooth and continuous evolution between the regimes or states. This is in contrast to quantum… 

Figures from this paper

Crossovers and quantum phase transitions in two-band superfluids: The evolution from BCS to Bose pairing by tuning interactions and band offset
We show that in two-band s -wave superfluids it is possible to induce quantum phase transitions (QPTs) by tuning intraband and interband s -wave interactions, in sharp contrast to single-band s -wave
Superconductivity in the twisted bilayer graphene: emergent mystery in the magic angle, the topological bosons and the Bardeen Cooper Schrieffer – Bose Einstein unconventional crossover
ABSTRACT Theory of superconductivity in twisted bilayer graphene (tBLG) is presented, based on the fact that Dirac fermions are pairing creating the topological bosons as consequence of topologically
s-Wave Paired Electron and Hole Composite Fermion Trial State for Quantum Hall Bilayers with ν=1.
We introduce a new variational wave function for a quantum Hall bilayer at total filling ν_{T}=1, which is based on s-wave BCS pairing between electron composite fermions in one layer and hole
$s$-wave paired composite-fermion electron-hole trial state for quantum Hall bilayers with $\nu=1$
We introduce a new variational wavefunction for a quantum Hall bilayer at total filling ν = 1, which is based on s-wave BCS pairing between composite-fermion electrons in one layer and
Peaks of sound velocity in two color dense QCD: Quark saturation effects and semishort range correlations
We discuss stiffening of dense matter in two color QCD (QC2D) where hadrons are mesons and diquark baryons. We study two models which describe a transition of matter from the
Magnetized vector boson gas at any temperature
We study the thermodynamic properties of a relativistic magnetized neutral vector boson gas at any temperature. By comparing the results with the low temperature and the non relativistic descriptions
Exact theory of superconductivity from repulsion in narrow band systems.
We introduce an analytically-controlled theory of superconductivity from repulsive interaction in narrow band systems, where pairing is induced by virtual composite excitations at high energy. A
Spin-triplet superconductivity from excitonic effect in doped insulators
  • V. Cr'epelL. Fu
  • Physics
    Proceedings of the National Academy of Sciences of the United States of America
  • 2022
Significance We present a mechanism for unconventional superconductivity in doped band insulators, where short-ranged pairing interaction arises from Coulomb repulsion due to virtual interband or
Signatures of the BCS-BEC crossover in the yrast spectra of Fermi quantum rings
We study properties of the lowest energy states at non-zero total momentum (yrast states) of the Hubbard model for spin-1/2 fermions in the quantum ring configuration with attractive on-site


Critical temperature curve in BEC-BCS crossover.
The strongly correlated regime of the crossover from Bardeen-Cooper-Schrieffer pairing to Bose-Einstein condensation can be realized by diluting a system of two-component fermions with a short-range
The BCS-BEC crossover and the unitary fermi gas
There has been great excitement about the recent experimental and theoretical progress in elucidating the Bardeen-Cooper-Schrieffer (BCS) to Bose Einstein condensation (BEC) crossover in ultracold
Collective excitations of a degenerate gas at the BEC-BCS crossover.
In the regime of a strongly interacting Fermi gas, an abrupt change in the collective excitation frequency occurs, which may be a signature for a transition from a superfluid to a collisionless phase.
Quantum fluctuations in chains of Josephson junctions
We study the effect of quantum fluctuations of the phase on the low-temperature behavior of two models of Josephson junction chains with Coulomb interactions taken into account. The first model,
The BCS-BEC Crossover
This chapter presents the crossover from the Bardeen-Cooper-Schrieffer (BCS) state of weakly-correlated pairs of fermions to the Bose-Einstein condensation (BEC) of diatomic molecules in the atomic
Universal Relations for Fermions with Large Scattering Length
Particles with short-range interactions that produce a large scattering length have universal properties that depend only on the scattering length [1]. A system consisting of such particles is
Precise determination of the structure factor and contact in a unitary Fermi gas.
The experimental measurement utilizes Bragg spectroscopy to obtain the dynamic and static structure factors of ultracold Fermi gases at high momentum in the unitarity and molecular Bose-Einstein condensate regimes and performs quantum Monte Carlo calculations of the static properties.
Verification of universal relations in a strongly interacting Fermi gas.
Experimental verification of the Tan relations in a strongly interacting gas of fermionic atoms is provided by measuring both the microscopic and macroscopic quantities in the same system.
Vortices and superfluidity in a strongly interacting Fermi gas
Observation of vortex lattices in a strongly interacting, rotating Fermi gas that provide definitive evidence for superfluidity are reported and the crossover from a Bose–Einstein condensate of molecules to a Bardeen–Cooper–Schrieffer superfluid of loosely bound pairs is explored.
Revealing the Superfluid Lambda Transition in the Universal Thermodynamics of a Unitary Fermi Gas
The superfluid phase transition in a strongly interacting Fermi gas is observed by high-precision measurements of the local compressibility, density, and pressure, which completely determine the universal thermodynamics of these gases without any fit or external thermometer.