ABSTRACT
Resonances in the collision cross-sections of particles have a long history of theoretical studies in atomic and molecular physics [1-3], as well as in nuclear physics [4,5]. Their recent applications to Feshbach-resonance phenomena in cold gases often refer to a situation in which a dilute assembly of atoms is exposed to a spatially homogeneous magnetic field. Such an experimental setup allows magnetic tuning of the interatomic interactions. Early suggestions referred to the possibility of manipulating collision cross-sections in dilute vapors of spin-polarized hydrogen
and deuterium [6], as well as lithium [7]. At temperatures in the sub-microkelvin regime, the proposed applications of Feshbach resonances involved magnetic tuning of the s-wave scattering length [8], as well as formation of molecules [9], in trapped gases of alkali-metal atoms at the threshold between scattering and molecular binding.
