Thermometry of a deeply degenerate Fermi gas with a Bose-Einstein condensate

Lous, Rianne S.; Fritsche, Isabella; Jag, Michael; Bo, Huang; Grimm, Rudolf

doi:10.1103/physreva.95.053627

Cited by 31 publications

(32 citation statements)

References 55 publications

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“…As in earlier work on evaporative cooling of fermions (see e.g. [92]), we find that the optimal cooling is achieved just before the onset of spilling.…”

Section: A Transfer From Reservoir Into Main Dipole Trapsupporting

confidence: 86%

Production of a degenerate Fermi-Fermi mixture of dysprosium and potassium atoms

et al. 2018

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We report on the realization of a mixture of fermionic 161 Dy and fermionic 40 K where both species are deep in the quantum-degenerate regime. Both components are spin-polarized in their absolute ground states, and the low temperatures are achieved by means of evaporative cooling of the dipolar dysprosium atoms together with sympathetic cooling of the potassium atoms. We describe the trapping and cooling methods, in particular the final evaporation stage, which leads to Fermi degeneracy of both species. Analyzing cross-species thermalization we obtain an estimate of the magnitude of the inter-species s-wave scattering length at low magnetic field. We demonstrate magnetic levitation of the mixture as a tool to ensure spatial overlap of the two components. The properties of the Dy-K mixture make it a very promising candidate to explore the physics of strongly interacting mass-imbalanced Fermi-Fermi mixtures. arXiv:1810.13437v1 [cond-mat.quant-gas]

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“…As in earlier work on evaporative cooling of fermions (see e.g. [92]), we find that the optimal cooling is achieved just before the onset of spilling.…”

Section: A Transfer From Reservoir Into Main Dipole Trapsupporting

confidence: 86%

Production of a degenerate Fermi-Fermi mixture of dysprosium and potassium atoms

et al. 2018

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“…The effects of the trap inhomogeneity should moreover be reduced or even eliminated. We also note that current experimental breakthroughs with ultracold gases offer new exciting mixtures where both heavy and light impurities can be examined [48,[52][53][54][55].…”

Section: Discussionmentioning

confidence: 96%

“…The interaction is repulsive for small momenta in both cases since we have taken the impurities to be fermionic to model the experiments in Refs. [21,48]. In the case of heavy impurities with m/m B = 40/7 shown in Fig.…”

Section: A Weak Couplingmentioning

confidence: 99%

“…3-5 the Landau effective interaction f (0, p) calculated from (5), which gives the interaction between a zero momentum polaron and polaron with momentum p in the weak coupling limit. As above, we take k n a B = 0.2, T = 0, and a vanishing impurity concentration n. Innsbruck [48], and JILA [21] respectively. For unit mass ratio, m/m B = 1, we have from (5)…”

Section: A Weak Couplingmentioning

confidence: 99%

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Landau Effective Interaction between Quasiparticles in a Bose-Einstein Condensate

Camacho-Guardián

Bruun

2018

Phys. Rev. X

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Landau's description of the excitations in a macroscopic system in terms of quasiparticles stands out as one of the highlights in quantum physics. It provides an accurate description of otherwise prohibitively complex many-body systems, and has led to the development of several key technologies. In this paper, we investigate theoretically the Landau effective interaction between quasiparticles, socalled Bose polarons, formed by impurity particles immersed in a Bose-Einstein condensate (BEC). In the limit of weak interactions between the impurities and the BEC, we derive rigorous results for the effective interaction. They show that it can be strong even for weak impurity-boson interaction, if the transferred momentum/energy between the quasiparticles is resonant with a sound mode in the BEC. We then develop a diagrammatic scheme to calculate the effective interaction for arbitrary coupling strengths, which recovers the correct weak coupling results. Using this, we show that the Landau effective interaction in general is significantly stronger than that between quasiparticles in a Fermi gas, mainly because a BEC is more compressible than a Fermi gas. The interaction is particularly large near the unitarity limit of the impurity-boson scattering, or when the quasiparticle momentum is close to the threshold for momentum relaxation in the BEC. Finally, we show how the Landau effective interaction leads to a sizeable shift of the quasiparticle energy with increasing impurity concentration, which should be detectable with present day experimental techniques.

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“…being the geometrically averaged trap frequency of the bosons, m b their mass, and T = T c (1 − β) 1/3 [43,52]. Figure 3 shows the values of Ω eff that result from the data in Fig.…”

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confidence: 99%

Probing the Interface of a Phase-Separated State in a Repulsive Bose-Fermi Mixture

et al. 2018

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We probe the interface between a phase-separated Bose-Fermi mixture consisting of a small Bose-Einstein condensate of ^{41}K residing in a large Fermi sea of ^{6}Li. We quantify the residual spatial overlap between the two components by measuring three-body recombination losses for variable strength of the interspecies repulsion. A comparison with a numerical mean-field model highlights the importance of the kinetic energy term for the condensed bosons in maintaining the thin interface far into the phase-separated regime. Our results demonstrate a corresponding smoothing of the phase transition in a system of finite size.

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Thermometry of a deeply degenerate Fermi gas with a Bose-Einstein condensate

Cited by 31 publications

References 55 publications

Production of a degenerate Fermi-Fermi mixture of dysprosium and potassium atoms

Production of a degenerate Fermi-Fermi mixture of dysprosium and potassium atoms

Landau Effective Interaction between Quasiparticles in a Bose-Einstein Condensate

Probing the Interface of a Phase-Separated State in a Repulsive Bose-Fermi Mixture

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