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Fermion Mediated Pairing in the Ruderman-Kittel-Kasuya-Yosida to Efimov Transition Regime
Geyue Cai1, Henry Ando1, Sarah McCusker1
1The University of Chicago, The James Franck Institute, Enrico Fermi Institute, and Department of Physics, Chicago, Illinois 60637, USA.
Physical Review Letters
|March 13, 2026
Summary
We explored the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction and Efimov physics transition in Bose-Fermi mixtures. Our findings reveal a unique interplay between many-body physics and quantum phenomena.
Area of Science:
- Quantum Many-Body Physics
- Condensed Matter Physics
- Nuclear Physics
Background:
- Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction describes electron-mediated correlations between impurities.
- Efimov physics describes universal three-particle bound states with resonant interactions.
- Both phenomena have been observed separately in Bose-Fermi mixtures.
Purpose of the Study:
- To investigate the transition regime where RKKY interaction and Efimov physics coexist in strongly interacting Bose-Fermi mixtures.
- To explore the interplay between two-, three-, and many-body physics in such systems.
Main Methods:
- Studied a Bose-Fermi mixture of bosonic ^{133}Cs and fermionic ^{6}Li near a tunable interspecies Feshbach resonance.
- Utilized dispersion and relaxation measurements to probe the system's behavior.
Main Results:
- Observed a transition highlighted by a fermion-mediated scattering resonance between Cs atoms and a weaker resonance on Li atoms.
- Identified these resonances as reactive scattering events in the many-body regime, reducing to an Efimov resonance in the thermal gas regime.
Conclusions:
- Demonstrated the intriguing interplay of diverse quantum phenomena in a Bose-Fermi mixture.
- Connected condensed matter physics, nuclear physics, and quantum many-body chemistry through the observed RKKY-Efimov transition.
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