All-optical production of a degenerate mixture of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi mathvariant="normal">Li</mml:mi><mml:mprescripts /><mml:none /><mml:mrow><mml:mn>6</mml:mn></mml:mrow></mml:mmultiscripts></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi mathvariant="normal">K</mml:mi><mml:mprescripts /><mml:none /><mml:mrow><mml:mn>40</mml:mn></mml:mrow></mml:mmultiscripts></

Spiegelhalder, F. M.; Trenkwalder, Andreas; Naik, Devang; Kerner, G.; Wille, Erik; Hendl, G.; Schreck, Florian; Grimm, Rudolf

doi:10.1103/physreva.81.043637

Cited by 60 publications

(87 citation statements)

References 44 publications

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“…Although the superfluid phase transition of this Fermi-Fermi mixture has not been reported yet, the Fermi degenerate regime has been achieved [20,24]. In addition, since a tunable interaction associated with a Feshbach resonance between 6 Li and 40 K atoms [19,22,23], as well as the formation of 6 Li-40 K hetero molecules [21], has been realized, the observation of superfluid behaviors seems imminent.…”

Section: Introductionmentioning

confidence: 99%

Heteropairing and component-dependent pseudogap phenomena in an ultracold Fermi gas with different species with different masses

Hanai

Ōhashi

2014

Phys. Rev. A

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We investigate the superfluid phase transition and single-particle excitations in the BCS (BareenCooper-Schrieffer)-BEC (Bose-Einstein condensation) crossover regime of an ultracold Fermi gas with mass imbalance. In our recent paper [R. Hanai, et. al., Phys. Rev. A 88, 053621 (2013)we showed that an extended T -matrix approximation (ETMA) can overcome the serious problem known in the ordinary (non-self-consistent) T -matrix approximation that it unphysically gives double-valued superfluid phase transition temperature T c in the presence of mass imbalance. However, at the same time, the ETMA was also found to give the vanishing T c in the weak-coupling and highly mass-imbalanced case. In this paper, we inspect the correctness of this ETMA result, using the self-consistent T -matrix approximation (SCTMA). We show that the vanishing T c is an artifact of the ETMA, coming from an internal inconsistency of this theory. The superfluid phase transition actually always occurs, irrespective of the ratio of mass imbalance. We also apply the SCTMA to the pseudogap problem in a mass-imbalanced Fermi gas. We show that pairing fluctuations induce different pseudogap phenomena between the the light component and heavy component. We also point out that a 6 Li-40 K mixture is a useful system for the realization of a hetero pairing state, as well as for the study of component-dependent pseudogap phenomena.

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Section: Introductionmentioning

confidence: 99%

Heteropairing and component-dependent pseudogap phenomena in an ultracold Fermi gas with different species with different masses

Hanai

Ōhashi

2014

Phys. Rev. A

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“…The introduction of population imbalance [6,7] then paved the way to the rich physics of polarized Fermi gases [8,9]. The recent experimental efforts to create ultracold mixtures of two different fermionic species [10][11][12][13][14][15][16][17] have brought the field close to a new research frontier with intriguing new possibilities, e.g. related to novel types of superfluids and quantum phases [18,19] and to new few-body states [20,21].…”

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confidence: 99%

“…The preparation procedures are described in detail in Ref. [14]. At a temperature T ≈ 300 nK the Li component forms a degenerate Fermi sea with T /T Li F ≈ 0.3 and the K component is moderately degenerate with T /T K F ≈ 0.7; here the Fermi temperatures of both species are given by T Li F = 1.1 µK and T K F = 500 nK.…”

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confidence: 99%

Hydrodynamic Expansion of a Strongly Interacting Fermi-Fermi Mixture

et al. 2011

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We report on the expansion of an ultracold Fermi-Fermi mixture of 6 Li and 40 K under conditions of strong interactions controlled via an interspecies Feshbach resonance. We study the expansion of the mixture after release from the trap and, in a narrow magnetic field range, we observe two phenomena related to hydrodynamic behavior. The common inversion of the aspect ratio is found to be accompanied by a collective effect where both species stick together and expand jointly despite of their widely different masses. Our work constitutes a major experimental step for a controlled investigation of the many-body physics of this novel strongly interacting quantum system. Since the first observations of strongly interacting Fermi gases [1, 2] the field has produced many exciting results and provided important new insights into the manybody behavior of strongly interacting quantum matter [3][4][5]. The general interest cuts across different branches of physics, ranging from strongly correlated condensedmatter systems to neutron stars and the quark-gluon plasma.

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“…(7) and (8). For k-space regions where E k,1 > 0 and E k,2 > 0, the corresponding momentum distributions are equal n k,↑ = n k,↓ .…”

Section: B Topological Gapless-gapped Superfluidity Transitionmentioning

confidence: 99%

“…Following this huge success with singlespecies fermion mixtures, there has been increasing experimental interest in studying two-species Fermi-Fermi mixtures [3][4][5][6][7][8]. In particular, 6 Li-40 K mixtures have recently been trapped and interspecies Feshbach resonances have been identified, opening a new frontier in ultracold atom research to study exotic many-body phenomena, one of which is the possibility of studying fermion pairing in mixed dimensions [9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Cooper pairing and BCS-BEC evolution in mixed-dimensional Fermi gases

Iskin

Subaşı

2010

Phys. Rev. A

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Similar to what has recently been achieved with Bose-Bose mixtures [1], mixed-dimensional Fermi-Fermi mixtures can be created by applying a species-selective one-dimensional optical lattice to a two-species Fermi gas (σ ≡ {↑, ↓}), such a way that both species are confined to quasi-two-dimensional geometries determined by their hoppings along the lattice direction. We investigate the ground state phase diagram of superfluidity for such mixtures in the BCS-BEC evolution, and find normal, gapped superfluid, gapless superfluid, and phase separated regions. In particular, we find a stable gapless superfluid phase where the unpaired ↑ and ↓ fermions coexist with the paired (or superfluid) ones in different momentum space regions. This phase is in some ways similar to the Sarma state found in mixtures with unequal densities, but in our case, the gapless superfluid phase is unpolarized and most importantly it is stable against phase separation.

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All-optical production of a degenerate mixture ofLi6andK40

Cited by 60 publications

References 44 publications

Heteropairing and component-dependent pseudogap phenomena in an ultracold Fermi gas with different species with different masses

Heteropairing and component-dependent pseudogap phenomena in an ultracold Fermi gas with different species with different masses

Hydrodynamic Expansion of a Strongly Interacting Fermi-Fermi Mixture

Cooper pairing and BCS-BEC evolution in mixed-dimensional Fermi gases

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