Quantum-state controlled chemical reactions of ultracold potassium-rubidium molecules.

نویسندگان

  • S Ospelkaus
  • K-K Ni
  • D Wang
  • M H G de Miranda
  • B Neyenhuis
  • G Quéméner
  • P S Julienne
  • J L Bohn
  • D S Jin
  • J Ye
چکیده

How does a chemical reaction proceed at ultralow temperatures? Can simple quantum mechanical rules such as quantum statistics, single partial-wave scattering, and quantum threshold laws provide a clear understanding of the molecular reactivity under a vanishing collision energy? Starting with an optically trapped near-quantum-degenerate gas of polar 40K87Rb molecules prepared in their absolute ground state, we report experimental evidence for exothermic atom-exchange chemical reactions. When these fermionic molecules were prepared in a single quantum state at a temperature of a few hundred nanokelvin, we observed p-wave-dominated quantum threshold collisions arising from tunneling through an angular momentum barrier followed by a short-range chemical reaction with a probability near unity. When these molecules were prepared in two different internal states or when molecules and atoms were brought together, the reaction rates were enhanced by a factor of 10 to 100 as a result of s-wave scattering, which does not have a centrifugal barrier. The measured rates agree with predicted universal loss rates related to the two-body van der Waals length.

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عنوان ژورنال:
  • Science

دوره 327 5967  شماره 

صفحات  -

تاریخ انتشار 2010