Magnetic-field-induced tunability of spin Hamiltonians: Resonances and Efimov states in Yb2Ti2O7

Yasuyuki Kato, Shang-Shun Zhang, Yusuke Nishida +1 more

This paper proposes a mechanism to realize a high degree of magnetic field-induced tunability of the scattering length for the collision between magnons in quantum magnets with strong spin-orbit coupling.

Yusuke Nishida, Yasuyuki Kato, Cristian D. Batista

Daekyoung Kang

Martin Berninger, Alessandro Zenesini, Bo Huang +6 more

We report on the observation of triatomic Efimov resonances in an ultracold gas of cesium atoms. Exploiting the wide tunability of interactions resulting from three broad Feshbach resonances in the same spin channel, we measure magnetic-field dependent three-body recombination loss. The positions of the loss resonances yield corresponding values for the three-body parameter, which in universal few-body physics is required to describe three-body phenomena and, in particular, to fix the spectrum of Efimov states. Our observations show a robust universal behavior with a three-body parameter that stays essentially constant.

Cheng Chin, Vladan Vuletić, Andrew J. Kerman +1 more

Summary form only given, as follows. We report on the observation of narrow resonances associated with cold cesium collisions. A loss of laser cooled atoms in a trap is induced with a laser tuned to the blue of the 6S-6P transition. Several sharp resonances, with /spl sim/kHz intrinsic linewidths, are observed as a function of an applied magnetic field. The resonances appear near magnetically tunable Feshbach resonances. We identify the collision resonances as three-body processes. We have observed both mixed resonances where the collision partners are in different states and resonances consisting of identical atoms. These resonances are promising candidates of Efimov-like states. Efimov predicted that three-body, S-wave bound states could exist near a scattering resonance regardless of whether the pair-wise interaction is attractive or repulsive. These states were first predicted to occur in nuclear scattering, but have never been seen.

J. H. Macek