EVOLUTION FROM BCS SUPERCONDUCTIVITY TO BOSE-EINSTEIN CONDENSATION: MAPPING OF THE FERMIONIC ONTO A BOSONIC SYSTEM IN THE STRONG-COUPLING LIMIT

1999 ◽  
Vol 13 (05n06) ◽  
pp. 667-673
Author(s):  
F. PISTOLESI ◽  
G. C. STRINATI
Keyword(s):  
Strong Coupling ◽  
Real Space ◽  
Strong Coupling Limit ◽  
Einstein Condensation ◽  
Functional Integrals ◽  
Fermionic System ◽  
Bose Einstein Condensation ◽  
Direct Mapping ◽  
Effective System ◽  
Bose Einstein

We consider a system of fermions with an effective attractive interaction, for which formation of (real-space) bound pairs is expected to occur in the strong-coupling limit. We provide a direct mapping of this fermionic system onto an effective system of bosons with residual boson-boson interaction by means of functional integrals. We determine in this way the strength and the range of the residual boson-boson interaction.

Robust Polariton Bose–Einstein Condensation Laser via a Strong Coupling Microcavity

2020 ◽  
Vol 14 (12) ◽  
pp. 2000273
Author(s):  
Zhiyang Chen ◽  
Huying Zheng ◽  
Hai Zhu ◽  
Ziying Tang ◽  
Yaqi Wang ◽  
...  
Keyword(s):  
Strong Coupling ◽  
Einstein Condensation ◽  
Bose Einstein Condensation ◽  
Bose Einstein

scholarly journals Multi-regulator functional renormalization group for many-fermion systems

2017 ◽  
Vol 26 (01n02) ◽  
pp. 1740027
Author(s):  
Yuya Tanizaki ◽  
Tetsuo Hatsuda
Keyword(s):  
Renormalization Group ◽  
Collective Excitations ◽  
Einstein Condensation ◽  
Point Function ◽  
Functional Renormalization Group ◽  
Fermionic System ◽  
Bose Einstein Condensation ◽  
Fermion Systems ◽  
Two Component ◽  
Bose Einstein

We propose a method of multi-regulator functional renormalization group (MR-FRG) which is a novel formulation of functional renormalization group with multiple infrared (IR) regulators. It is applied to a two-component fermionic system with an attractive contact interaction to study crossover phenomena between the Bardeen–Cooper–Schrieffer (BCS) phase and the Bose–Einstein condensation (BEC) phase. To control both the fermionic one-particle excitations and the bosonic collective excitations, IR regulators are introduced, one for the fermionic two-point function and another for the four-fermion vertex. It is shown that the Nozières–Schmitt-Rink (NSR) theory, which is successful to capture qualitative features of the BCS–BEC crossover, can be derived from MR–FRG. Some aspects of MR-FRG to go beyond the NSR theory are also discussed.

scholarly journals TOWARDS BOSE–EINSTEIN CONDENSATION OF ELECTRON PAIRS: ROLE OF SCHWINGER BOSONS

1999 ◽  
Vol 13 (08) ◽  
pp. 925-937 ◽  
Author(s):  
GANG SU ◽  
MASUO SUZUKI
Keyword(s):  
Hilbert Space ◽  
Hubbard Model ◽  
Strong Coupling ◽  
Einstein Condensation ◽  
Electron Pairs ◽  
Bose Einstein Condensation ◽  
Attractive Hubbard Model ◽  
Hilbert Subspace ◽  
Bose Einstein

It can be shown that the bosonic degree of freedom of the tightly bound on-site electron pairs could be separated as Schwinger bosons. This is implemented by projecting the whole Hilbert space into the Hilbert subspace spanned by states of two kinds of Schwinger bosons (to be called binon and vacanon) subject to a constraint that these two kinds of bosonic quasiparticles cannot occupy the same site. We argue that a binon is actually a kind of quantum fluctuations of electron pairs, and a vacanon corresponds to a vacant state. These two bosonic quasiparticles may be responsible for the Bose–Einstein condensation (BEC) of the system associated with electron pairs. These concepts are also applied to the attractive Hubbard model with strong coupling, showing that it is quite useful. The relevance of the present arguments to the existing theories associated with the BEC of electron pairs is briefly commented.

Strong Coupling: Polariton Bose Condensation

2017 ◽  
Author(s):  
Alexey V. Kavokin ◽  
Jeremy J. Baumberg ◽  
Guillaume Malpuech ◽  
Fabrice P. Laussy
Keyword(s):  
Strong Coupling ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Dissipative System ◽  
Bose Condensation ◽  
Einstein Condensation ◽  
Strong Coupling Regime ◽  
Stimulated Scattering ◽  
Exciton Polaritons ◽  
Bose Einstein

In this Chapter we address the physics of Bose-Einstein condensation and its implications to a driven-dissipative system such as the polariton laser. We discuss the dynamics of exciton-polaritons non-resonantly pumped within a microcavity in the strong coupling regime. It is shown how the stimulated scattering of exciton-polaritons leads to formation of bosonic condensates that may be stable at elevated temperatures, including room temperature.

Systems with Condensates and Pairing

2018 ◽  
Author(s):  
Klaus Morawetz
Keyword(s):  
Critical Parameters ◽  
Einstein Condensation ◽  
Cooper Pairs ◽  
Pair Breaking ◽  
Systematic Theory ◽  
Bose Einstein Condensation ◽  
T Matrix ◽  
The Stability ◽  
Bose Einstein

The Bose–Einstein condensation and appearance of superfluidity and superconductivity are introduced from basic phenomena. A systematic theory based on the asymmetric expansion of chapter 11 is shown to correct the T-matrix from unphysical multiple-scattering events. The resulting generalised Soven scheme provides the Beliaev equations for Boson’s and the Nambu–Gorkov equations for fermions without the usage of anomalous and non-conserving propagators. This systematic theory allows calculating the fluctuations above and below the critical parameters. Gap equations and Bogoliubov–DeGennes equations are derived from this theory. Interacting Bose systems with finite temperatures are discussed with successively better approximations ranging from Bogoliubov and Popov up to corrected T-matrices. For superconductivity, the asymmetric theory leading to the corrected T-matrix allows for establishing the stability of the condensate and decides correctly about the pair-breaking mechanisms in contrast to conventional approaches. The relation between the correlated density from nonlocal kinetic theory and the density of Cooper pairs is shown.

scholarly journals Bose Einstein condensation in a magnetic double-well potential

2003 ◽  
Vol 5 (2) ◽  
pp. S119-S123 ◽  
Author(s):  
T G Tiecke ◽  
M Kemmann ◽  
Ch Buggle ◽  
I Shvarchuck ◽  
W von Klitzing ◽  
...  
Keyword(s):  
Einstein Condensation ◽  
Bose Einstein Condensation ◽  
Bose Einstein ◽  
Double Well Potential
Sign in / Sign up

Export Citation Format

Share Document