Numerical simulations for realistic experimental parameters demonstrate that laser cooling on the attractive side of the Feshbach resonance can drive fermions much below the superfluid transition. For the assumed set of experimental parameters the transition takes place at $0.35T_F$ , and laser cooling can drive the system down to at least $0.085T_F$ in a time of a few seconds. Superfluid growth is self-consistently included in simulations.Numerical simulations for realistic experimental parameters demonstrate that laser cooling on the attractive side of the Feshbach resonance can drive fermions much below the superfluid transition. For the assumed set of experimental parameters the transition takes place at $0.35T_F$, and laser cooling can drive the system down to at least $0.085T_F$ in a time of a few seconds. Superfluid growth is self-consistently included in simulations.

arXiv:cond-mat/0410704Oct 27, 20040 citations

Laser cooling down to molecular condensate

Jacek Dziarmaga, Maciej Lewenstein

On the repulsive side of the Feshbach resonance fermionic atoms can bind into diatomic molecules which at low enough temperature condense into molecular Bose-Einstein condensate. Sufficiently close to the resonance the molecules are bound so weakly that a significant fraction of unbound fermionic atoms survives even below the temperature of condensation. In this paper we show that laser cooling of the unbound fermionic atoms can reduce temperature of mixture of atoms and molecules below the condensation temperature. Numerical simulations for reasonable experimental parameters show that it is possible to achieve molecular condensate after a few seconds of laser cooling.On the repulsive side of the Feshbach resonance fermionic atoms can bind into diatomic molecules which at low enough temperature condense into molecular Bose-Einstein condensate. Sufficiently close to the resonance the molecules are bound so weakly that a significant fraction of unbound fermionic atoms survives even below the temperature of condensation. In this paper we show that laser cooling of the unbound fermionic atoms can reduce temperature of mixture of atoms and molecules below the condensation temperature. Numerical simulations for reasonable experimental parameters show that it is possible to achieve molecular condensate after a few seconds of laser cooling.

arXiv:cond-mat/0502247Physical Review ASep 9, 20056 citations

Signatures of superfluidity in atomic Fermi gases

Mirta Rodríquez Pinilla

After the experimental realization of Bose-Einstein condensation in dilute gases of alkali atoms, experimentalists started to trap the fermionic isotopes. The degenerate state for fermions was reported in 1999. The main objective of these experiments is to obtain superfluidity of fermionic gases. When there are attractive interactions between the fermions, the Fermi sea becomes unstable with respect to the formation of atomic Cooper pairs and the system becomes a superfluid. It turns out that the existing experimental cooling techniques allow minimum temperatures for fermions of the order of the Fermi temperature. Using Feshbach resonances induced by magnetic fields enhances the effective interactions between the atoms leading to superfluid transition temperatures of the order of the Fermi energy. This is a completely new regime of fermionic superfluidity far from the BCS superconductors, He and even high- superconductors. The achievement of superfluidity on gasesAfter the experimental realization of Bose-Einstein condensation in dilute gases of alkali atoms, experimentalists started to trap the fermionic isotopes. The degenerate state for fermions was reported in 1999. The main objective of these experiments is to obtain superfluidity of fermionic gases. When there are attractive interactions between the fermions, the Fermi sea becomes unstable with respect to the formation of atomic Cooper pairs and the system becomes a superfluid. It turns out that the existing experimental cooling techniques allow minimum temperatures for fermions of the order of the Fermi temperature. Using Feshbach resonances induced by magnetic fields enhances the effective interactions between the atoms leading to superfluid transition temperatures of the order of the Fermi energy. This is a completely new regime of fermionic superfluidity far from the BCS superconductors, He and even high- superconductors. The achievement of superfluidity on gases

Nov 14, 20032 citations

Trapped resonant fermions above the superfluid transition temperature

Chi-Ho Cheng, Sungkit Yip

We investigate trapped resonant fermions with unequal populations within the local density approximation above the superfluid transition temperature. By tuning the attractive interaction between fermions via Feshbach resonance, the system evolves from weakly interacting fermi gas to strongly interacting fermi gas, and finally becomes a Bose-Fermi mixture. The density profiles of fermions are examined and compared with experiments. We also point out the simple relationships between the local density, the axial density, and the gas pressure within the local density approximation.We investigate trapped resonant fermions with unequal populations within the local density approximation above the superfluid transition temperature. By tuning the attractive interaction between fermions via Feshbach resonance, the system evolves from weakly interacting fermi gas to strongly interacting fermi gas, and finally becomes a Bose-Fermi mixture. The density profiles of fermions are examined and compared with experiments. We also point out the simple relationships between the local density, the axial density, and the gas pressure within the local density approximation.

arXiv:cond-mat/0611578Physical Review BJan 26, 200719 citations

Bose–Einstein condensation

M. Inguscio, L. Fallani

Besides the enormous opportunities offered by spectroscopy and atom interferometry, laser cooling has opened up the possibility of experimentally realizing and manipulating quantum degenerate gases: Bose–Einstein condensates and degenerate Fermionic systems. This chapter starts with an illustration of key experimental techniques, such as magnetic trapping, evaporative cooling, and Feshbach resonances. It then turns to the physics of atomic Bose–Einstein condensates, discussing their superfluid behaviour, their coherence properties, and their application to precise measurements. It also describes the experimental investigation of ultracold Fermi gases and fermionic superfluidity, as well as ongoing research into ultracold polar molecules.Besides the enormous opportunities offered by spectroscopy and atom interferometry, laser cooling has opened up the possibility of experimentally realizing and manipulating quantum degenerate gases: Bose–Einstein condensates and degenerate Fermionic systems. This chapter starts with an illustration of key experimental techniques, such as magnetic trapping, evaporative cooling, and Feshbach resonances. It then turns to the physics of atomic Bose–Einstein condensates, discussing their superfluid behaviour, their coherence properties, and their application to precise measurements. It also describes the experimental investigation of ultracold Fermi gases and fermionic superfluidity, as well as ongoing research into ultracold polar molecules.

Oxford University Press eBooksSep 1, 20132 citations

Resonance Superfluidity in a Quantum Degenerate Fermi Gas

Murray Holland, S. J. J. M. F. Kokkelmans, M. L. Chiofalo +1 more

We consider the superfluid phase transition that arises when a Feshbach resonance pairing occurs in a dilute Fermi gas. We apply our theory to consider a specific resonance in potassium ((40)K), and find that for achievable experimental conditions, the transition to a superfluid phase is possible at the high critical temperature of about 0.5T(F). Observation of superfluidity in this regime would provide the opportunity to experimentally study the crossover from the superfluid phase of weakly coupled fermions to the Bose-Einstein condensation of strongly bound composite bosons.We consider the superfluid phase transition that arises when a Feshbach resonance pairing occurs in a dilute Fermi gas. We apply our theory to consider a specific resonance in potassium ((40)K), and find that for achievable experimental conditions, the transition to a superfluid phase is possible at the high critical temperature of about 0.5T(F). Observation of superfluidity in this regime would provide the opportunity to experimentally study the crossover from the superfluid phase of weakly coupled fermions to the Bose-Einstein condensation of strongly bound composite bosons.

arXiv:cond-mat/0103479Physical Review LettersAug 31, 2001506 citations

0.35T_F

, and laser cooling can drive the system down to at least

0.085T_F

in a time of a few seconds. Superfluid growth is self-consistently included in simulations.