Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE

Superconductivity of fermion atoms with positive scattering length

Igor V. Kazinets, I. E. Mazets, Boris G. Matisov

Published Nov 27, 2000• 0 citations
Publisher

Abstract

The possibility of creating Cooper pairs of fermion-atoms imbedded into a degenerate bose-gas is considered. The transition of this system to a superconducting state under certain conditions is demonstrated to be possible, even if there is repulsion between fermions.
DOI
10.1117/12.407670

Related papers

Achieving a BCS Transition in an Atomic Fermi Gas

Lincoln D. Carr, Gora V. Shlyapnikov, Yvan Castin

We consider a gas of cold fermionic atoms having two spin components with interactions characterized by their s-wave scattering length a. At positive scattering length the atoms form weakly bound bosonic molecules which can be evaporatively cooled to undergo Bose-Einstein condensation, whereas at negative scattering length BCS pairing can take place. It is shown that, by adiabatically tuning the scattering length a from positive to negative values, one may transform the molecular Bose-Einstein condensate into a highly degenerate atomic Fermi gas, with the ratio of temperature to Fermi temperature T/T(F) approximately 10(-2). The corresponding critical final value of k(F)/a/, which leads to the BCS transition, is found to be about one-half, where k(F) is the Fermi momentum.

arXiv:cond-mat/0308306•Physical Review Letters•Apr 15, 2004•112 citations

A dilute atomic Fermi system with a large positive scattering length

Aurel Bulgac, Paulo F. Bedaque, A. C. Fonseca

We show that a dilute atomic Fermi system at sufficiently low temperatures, can display fermionic superfluidity, even in the case of a repulsive atom-atom interaction, when the scattering length is positive. The attraction leading to the formation of Cooper pairs is provided by the exchange of Bogoliubov phonons if a fraction of the atoms form a BEC of weakly bound molecules.

arXiv:cond-mat/0306302•Jun 11, 2003•4 citations

Laser Probing of Atomic Cooper Pairs

Päivi Törmä, P. Zoller

We consider a gas of attractively interacting cold fermionic atoms which are manipulated by laser light. The laser induces a transition from an internal state with large negative scattering length to one with almost no interactions. The process can be viewed as a tunneling of atomic population between the superconducting and the normal states of the gas. It can be used to detect the BCS ground state and to measure the superconducting order parameter.

arXiv:cond-mat/0001341•Physical Review Letters•Jul 17, 2000•111 citations

Poking at Atomic Cooper Pairs

The recent observation of the onset of degeneracy in a Fermi gas, in which the atoms are cooled to such low temperatures that their associated de Broglie waves start to overlap, has opened up new opportunities in atomic and quantum physics. One prediction is that the interaction between Fermionic atoms can be tuned to form Cooper pairs, just as two electrons do in superconductors when they overcome their Coulombic repulsion and pair up. However, the expectedly small superconducting gap and the nature of the Fermionic system will require new techniques. Törma and Zoller propose using laser pulses to detect the superconducting ground state of the atomic Cooper pair and determine the extent of the pairing. Lasers would be used to tune and manipulate the coupling between the internal energy levels of the atoms, which would alter their interaction strength, and should result in a controllable and measurable phase transition between the superconducting and normal states. — ISO

Science•Aug 4, 2000•0 citations

Ground state of two-component degenerate fermionic gases

Tomasz Karpiuk, Mirosław Brewczyk, Kazimierz Rza̧żewski

We analyze the ground state of the two-component gas of trapped ultracold fermionic atoms. We neglect the forces between atoms in the same hyperfine state (the same component). For the case when the forces between distinguishable atoms (i.e., atoms in different hyperfine states) are repulsive (positive mutual scatteringlength), we find the existence of critical interaction strength above which one atomic fraction expels the other from the center of the trap. When atoms from different components attract each other (negative mutual scattering length) the ground state of the system dramatically changes its structure for strong enough attraction---the Cooper pairs built of atoms in different hyperfine states appear.

arXiv:cond-mat/0308497•Physical Review A•Apr 5, 2004•27 citations

Degenerate Fermi gases

Patrizia Vignolo

The main topic of these lectures is the physics of quantum degenerate atomic Fermi gases both under uniform confinement and in harmonic traps. To begin with, a general introduction on ideal Fermi gases is proposed. This "academic" limit is relevant in experiments where ultracold fermionic atoms are all polarized in a single spin state: the low atom momenta together with the fermionic nature of the atoms forbid atomic s-wave scattering and the atoms can be considered as free. Interactions are then introduced for the case of a gas with two spin components. Interactions can be tuned via Feshbach resonances and control the microscopic features of the superfluid phase, ranging from the BCS limit (formation of Cooper pairs) to the BEC limit (Bose-Einstein condensation of dimers). Various theoretical approaches for the description of the BCS-BEC crossover and their predictions in comparison with the experimental results are discussed.

Oxford University Press eBooks•May 5, 2011•0 citations
We consider a gas of cold fermionic atoms having two spin components with interactions characterized by their s-wave scattering length a. At positive scattering length the atoms form weakly bound bosonic molecules which can be evaporatively cooled to undergo Bose-Einstein condensation, whereas at negative scattering length BCS pairing can take place. It is shown that, by adiabatically tuning the scattering length a from positive to negative values, one may transform the molecular Bose-Einstein condensate into a highly degenerate atomic Fermi gas, with the ratio of temperature to Fermi temperature T/T(F) approximately 10(-2). The corresponding critical final value of k(F)/a/, which leads to the BCS transition, is found to be about one-half, where k(F) is the Fermi momentum.
The recent observation of the onset of degeneracy in a Fermi gas, in which the atoms are cooled to such low temperatures that their associated de Broglie waves start to overlap, has opened up new opportunities in atomic and quantum physics. One prediction is that the interaction between Fermionic atoms can be tuned to form Cooper pairs, just as two electrons do in superconductors when they overcome their Coulombic repulsion and pair up. However, the expectedly small superconducting gap and the nature of the Fermionic system will require new techniques. Törma and Zoller propose using laser pulses to detect the superconducting ground state of the atomic Cooper pair and determine the extent of the pairing. Lasers would be used to tune and manipulate the coupling between the internal energy levels of the atoms, which would alter their interaction strength, and should result in a controllable and measurable phase transition between the superconducting and normal states. — ISO
We analyze the ground state of the two-component gas of trapped ultracold fermionic atoms. We neglect the forces between atoms in the same hyperfine state (the same component). For the case when the forces between distinguishable atoms (i.e., atoms in different hyperfine states) are repulsive (positive mutual scatteringlength), we find the existence of critical interaction strength above which one atomic fraction expels the other from the center of the trap. When atoms from different components attract each other (negative mutual scattering length) the ground state of the system dramatically changes its structure for strong enough attraction---the Cooper pairs built of atoms in different hyperfine states appear.
The main topic of these lectures is the physics of quantum degenerate atomic Fermi gases both under uniform confinement and in harmonic traps. To begin with, a general introduction on ideal Fermi gases is proposed. This "academic" limit is relevant in experiments where ultracold fermionic atoms are all polarized in a single spin state: the low atom momenta together with the fermionic nature of the atoms forbid atomic s-wave scattering and the atoms can be considered as free. Interactions are then introduced for the case of a gas with two spin components. Interactions can be tuned via Feshbach resonances and control the microscopic features of the superfluid phase, ranging from the BCS limit (formation of Cooper pairs) to the BEC limit (Bose-Einstein condensation of dimers). Various theoretical approaches for the description of the BCS-BEC crossover and their predictions in comparison with the experimental results are discussed.