@article { ISI:000278140000096, title = {Collisional decoherence of internal-state superpositions in a trapped ultracold gas}, journal = {PHYSICAL REVIEW A}, volume = {81}, number = {5}, year = {2010}, month = {MAY}, pages = {052701}, abstract = {We analyze collisional decoherence of atoms or molecules prepared in a coherent superposition of nondegenerate internal states at ultralow temperatures and placed in an ultracold buffer gas. Our analysis is applicable for an arbitrary bath-particle to tracer-particle mass ratio. Both elastic and inelastic collisions contribute to decoherence. We obtain an expression relating the observable decoherence rate to pairwise scattering properties, specifically the scattering lengths and low-temperature scattering amplitudes. We consider the dependence on the bath-particle to tracer-particle mass ratio for the case of light bath and heavy tracer particles. The expressions obtained may be useful in low-temperature applications where accurate estimates of decoherence rates are needed. The results suggest a method for determining the scattering lengths of atoms and molecules in different internal states by measuring decoherence-induced damping of coherent oscillations.}, issn = {1050-2947}, doi = {10.1103/PhysRevA.81.052701}, author = {Hemming, C. J. and Krems, R. V.} }