Superfluidity At some of the coldest temperatures achieved in the laboratory, researchers can coax dilute gases of atoms into becoming a superfluid, with the whole gas behaving as one entity. Bosonic atoms, which like to congregate in one state, achieve this willingly. Fermions, which effectively repel each other, require more persuasion. Ferrier-Barbut et al. made a superfluid mixture of two gases, one made up of bosons and one of fermions. They used two isotopes of lithium, fermionic 6Li and bosonic 7Li. When they made the mixture oscillate, the two components took turns feeding energy into each other. Science , this issue p. [1035][1] [1]: /lookup/doi/10.1126/science.1255380Superfluidity At some of the coldest temperatures achieved in the laboratory, researchers can coax dilute gases of atoms into becoming a superfluid, with the whole gas behaving as one entity. Bosonic atoms, which like to congregate in one state, achieve this willingly. Fermions, which effectively repel each other, require more persuasion. Ferrier-Barbut et al. made a superfluid mixture of two gases, one made up of bosons and one of fermions. They used two isotopes of lithium, fermionic 6Li and bosonic 7Li. When they made the mixture oscillate, the two components took turns feeding energy into each other. Science , this issue p. [1035][1] [1]: /lookup/doi/10.1126/science.1255380

ScienceAug 28, 20140 citations

Double superfluidity of Bose-Fermi mixtures

Fr 'ed 'eric Chevy, Marion Delehaye, Igor Ferrier-Barbut +2 more

Bulletin of the American Physical SocietyJun 11, 20150 citations

Cold asymmetrical fermion superfluids - eScholarship

Heron Caldas

Dec 19, 20030 citations

Two-Species Fermion Mixtures with Population Imbalance

M. Iskin, C. A. R. Sá de Melo

We analyze the phase diagram of uniform superfluidity for two-species fermion mixtures from the Bardeen-Cooper-Schrieffer to Bose-Einstein condensation (BEC) limit as a function of the scattering parameter and population imbalance. We find at zero temperature that the phase diagram of population imbalance versus scattering parameter is asymmetric for unequal masses, having a larger stability region for uniform superfluidity when the lighter fermions are in excess. In addition, we find topological quantum phase transitions associated with the disappearance or appearance of momentum space regions of zero quasiparticle energies. Lastly, near the critical temperature, we derive the Ginzburg-Landau equation and show that it describes a dilute mixture of composite bosons and unpaired fermions in the BEC limit.We analyze the phase diagram of uniform superfluidity for two-species fermion mixtures from the Bardeen-Cooper-Schrieffer to Bose-Einstein condensation (BEC) limit as a function of the scattering parameter and population imbalance. We find at zero temperature that the phase diagram of population imbalance versus scattering parameter is asymmetric for unequal masses, having a larger stability region for uniform superfluidity when the lighter fermions are in excess. In addition, we find topological quantum phase transitions associated with the disappearance or appearance of momentum space regions of zero quasiparticle energies. Lastly, near the critical temperature, we derive the Ginzburg-Landau equation and show that it describes a dilute mixture of composite bosons and unpaired fermions in the BEC limit.

arXiv:cond-mat/0604184Physical Review LettersSep 8, 2006126 citations

SUPERFLUIDITY IN A GAS OF STRONGLY INTERACTING FERMIONS

Wolfgang Ketterle, Yong-il Shin, André Schirotzek +1 more

WORLD SCIENTIFIC eBooksNov 1, 20100 citations

Superfluid-insulator transition and fermion pairing in Bose-Fermi mixtures

Kun Yang

It is well known that bosons on an optical lattice undergo a second-order superfluid-insulator transition (SIT) when the lattice potential increases. In this paper, we study SIT when fermions coexist with the bosons. We find that the critical properties of particle-hole symmetric SIT with dynamical exponent $z=1$ is modified when fermions are present; it either becomes a fluctuation-driven first-order transition or a different second-order transition. On the other hand, the more generic particle-hole asymmetric (with $z=2$ ) SIT is stable against coupling with fermions. We also discuss pairing interaction between fermions mediated by quantum critical fluctuations near SIT and show that the fermion pairing and/or superfluid transition temperature peaks near SIT when a single species of fermion is present.It is well known that bosons on an optical lattice undergo a second-order superfluid-insulator transition (SIT) when the lattice potential increases. In this paper, we study SIT when fermions coexist with the bosons. We find that the critical properties of particle-hole symmetric SIT with dynamical exponent $z=1$ is modified when fermions are present; it either becomes a fluctuation-driven first-order transition or a different second-order transition. On the other hand, the more generic particle-hole asymmetric (with $z=2$) SIT is stable against coupling with fermions. We also discuss pairing interaction between fermions mediated by quantum critical fluctuations near SIT and show that the fermion pairing and/or superfluid transition temperature peaks near SIT when a single species of fermion is present.

arXiv:0707.4189Physical Review BFeb 19, 200811 citations

z=1

is modified when fermions are present; it either becomes a fluctuation-driven first-order transition or a different second-order transition. On the other hand, the more generic particle-hole asymmetric (with

z=2

) SIT is stable against coupling with fermions. We also discuss pairing interaction between fermions mediated by quantum critical fluctuations near SIT and show that the fermion pairing and/or superfluid transition temperature peaks near SIT when a single species of fermion is present.