Observation of fermion-mediated interactions between bosonic atoms

DeSalvo, B. J.; Patel, Krutik; Cai, Geyue; Chin, Cheng

doi:10.1038/s41586-019-1055-0

Cited by 117 publications

(108 citation statements)

References 31 publications

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“…When using our measured values for a bf 2 −a bf 1 and a previously known value for a bf 1 = −185± 7 a 0 (40) we calculate the expected mediated interaction shift and find ξ = 1.32 ± 0.18 stat ± 0.35 sys , in good agreement with ξ = 1 theory (18) and a recent mechanical measurement (13).…”

Section: Rkky Mediated Interactions Can Be Intuitively Understood a supporting

confidence: 87%

Observation of Spin-Spin Fermion-Mediated Interactions between Ultracold Bosons

et al. 2020

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Interactions in an ultracold boson-fermion mixture are often manifested by elastic collisions. In a mixture of a condensed Bose gas (BEC) and spin polarized degenerate Fermi gas (DFG), fermions can mediate spin-spin interactions between bosons, leading to an effective long-range magnetic interaction analogous to Ruderman-Kittel-Kasuya-Yosida (RKKY) (1-3) interaction in solids.We used Ramsey spectroscopy of the hyperfine clock transition in a 87 Rb BEC to measure the interaction mediated by a 40 K DFG. By controlling the bosons density we isolated the effect of mediated interactions from mean-field frequency shifts due to direct collision with fermions. We measured an increase of boson spin-spin interaction by a factor of η = 1.43 ± 0.06 stat ± 0.17 sys in the presence of the DFG, providing a clear evidence of spin-spin fermion mediated interaction. Decoherence in our system was dominated by inhomogeneous boson density shift, which increased significantly in the presence of the DFG, again indicating mediated interactions. We also measured a frequency shift due to boson-fermion interactions in accordance with a scattering length difference of a bf 2 −a bf 1 = −5.14±0.74 stat ±2.20 sys a 0 between the clock-transition states, a first measurement beyond the low-energy elastic approximation (4,5) in this mixture. This interaction can be tuned with a future use of a bosonfermion Feshbach resonance. Fermion-mediated interactions can potentially give rise to interesting new magnetic phases and extend the Bose-Hubbard model when the atoms are placed in an optical lattice.

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Section: Rkky Mediated Interactions Can Be Intuitively Understood a supporting

confidence: 87%

Observation of Spin-Spin Fermion-Mediated Interactions between Ultracold Bosons

et al. 2020

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“…Clearly, as figure 5 suggests, going to larger samples the solutions change their character from the soliton-like (black solid and dashed lines, left corner) reported by us already some time ago [35] to the one with fully developed flat part typical for droplets (green solid and dashed lines). Noticeably, appearance of a train of Bose-Fermi solitons for appropriately tuned Bose-Fermi interaction, as claimed in [35], has been confirmed in recent experiment [36]. In 1D the fermions can be considered as impurities-much smaller in fraction in comparison to 2D and 3D [13] cases, yet essential for the droplet formation.…”

Section: D Mixturesupporting

confidence: 53%

Self-bound Bose–Fermi liquids in lower dimensions

et al. 2019

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We study weakly interacting mixtures of ultracold atoms composed of bosonic and fermionic species in 2D and 1D. When interactions between particles are appropriately tuned, self-bound quantum liquids can be formed. We show that while formation of these droplets in 2D is due to the higher order correction terms contributing to the total energy and originating in quantum fluctuations, in 1D geometry the quantum fluctuations have a negligible role on formation of the self-bound systems. The leading mean-field interactions are then sufficient for droplet formation in 1D. We analyze energetic stability for 2D and 1D systems and predict values of equilibrium densities of droplets.

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“…These results are compared to the results we demonstrated in the previous section, which were achieved within the hydrodynamic description of the Bose-Fermi mixture. The atomic-orbital approach has been used by us previously to study the dynamics of Bose-Fermi solitons in quasi-one-dimensional mixtures [25,27] (observed experimentally in [26]) as well as fermionic mixtures, in particular in the context of formation of Cooper pairs [46].…”

Section: Finite System Analysis -Atomic-orbital Approachmentioning

confidence: 99%

Quantum Bose-Fermi droplets

Rakshit¹,

Karpiuk

Brewczyk

et al. 2019

SciPost Phys.

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We study the stability of a zero temperature mixture of attractively interacting degenerate bosons and spin-polarized fermions in the absence of confinement. We demonstrate that higher order corrections to the standard mean-field energy can lead to a formation of Bose-Fermi liquid droplets -self-bound systems in threedimensional space. The stability analysis of the homogeneous case is supported by numerical simulations of finite systems by explicit inclusion of surface effects. We discuss the experimental feasibility of formation of quantum droplets and indicate the main obstacle -inelastic three-body collisions.

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Observation of fermion-mediated interactions between bosonic atoms

Cited by 117 publications

References 31 publications

Observation of Spin-Spin Fermion-Mediated Interactions between Ultracold Bosons

Observation of Spin-Spin Fermion-Mediated Interactions between Ultracold Bosons

Self-bound Bose–Fermi liquids in lower dimensions

Quantum Bose-Fermi droplets

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