Authors: Scott T. Sullivan, Wade G. Rellergert, Steven J. Schowalter, Svetlana Kotochigova, Kuang Chen, Christian Schneider, Eric R. Hudson
Using collisions with ultracold 40Ca, we experimentally demonstrate the quenching of the vibrational motion in co-trapped BaCl+. This quenching rate is found to be comparable to the Langevin scattering rate, which is over four orders of magnitude more efficient than traditional sympathetic cooling schemes. The high cooling rate, a consequence of a strong interaction potential (due to the high polarizability of calcium), along with the low collision energies involved, leads to molecular samples with vibrational ground-state occupancies of at least 90%. Our demonstration uses a novel thermometry technique that relies on relative photodissociation yields. This method has the potential to be extended to many atom-ion pairs and thus represents a critical step towards a robust, general technique to create large samples of ultracold groundstate molecular ions.
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