Rovibrational quenching of Caf and BaF in a cryogenic helium bath
ORAL
Abstract
Polar molecules at ultralow temperatures provide powerful opportunities for quantum science and emerging quantum technologies [1]. Among direct molecular cooling approaches, buffer-gas cooling is a crucial step toward enabling efficient laser cooling of dipolar species into the sub-microkelvin regime [2]. The performance of this technique is governed by the microscopic dynamics of atom–molecule collisions, which determine thermalization and energy transfer processes [3].
Of particular interest is the cooling of alkaline-earth monofluorides, such as CaF and BaF. Recent experiments have revealed a significant difference in the rovibrational relaxation rates of these two molecules when immersed in a cryogenic helium buffer gas at cold temperatures.
In this work, we explain the origin of these differences by means of quantum mechanical scattering calculations. We compute accurate atom–molecule interaction potentials using high-level quantum chemistry methods and solve the multichannel Schrödinger equation to obtain rovibrational relaxation rates. Our results are in good agreement with experimental observations and show that the distinct sympathetic cooling behavior of CaF and BaF arises from differences in the anisotropy of the interaction potential and from the location of shape resonances in the scattering dynamics.
[1] J. L. Bohn, A. M. Rey, and J. Ye, Cold molecules: Progress in quantum engineering of chemistry and quantum matter, Science 357, 1002 (2017).
[2] S. L. Cornish, M. R. Tarbutt, and K. R. A. Hazzard, “Quantum computation and quantum simulation with ultracold molecules,” Nat. Phys. 20, 730–740 (2024)
[3] N. R. Hutzler, H.-I. Lu, and J. M. Doyle, The buffer gas beam: An intense, cold, and slow source for atoms and molecules, Chemical Reviews, Chemical Reviews 112, 4803 (2012).
Of particular interest is the cooling of alkaline-earth monofluorides, such as CaF and BaF. Recent experiments have revealed a significant difference in the rovibrational relaxation rates of these two molecules when immersed in a cryogenic helium buffer gas at cold temperatures.
In this work, we explain the origin of these differences by means of quantum mechanical scattering calculations. We compute accurate atom–molecule interaction potentials using high-level quantum chemistry methods and solve the multichannel Schrödinger equation to obtain rovibrational relaxation rates. Our results are in good agreement with experimental observations and show that the distinct sympathetic cooling behavior of CaF and BaF arises from differences in the anisotropy of the interaction potential and from the location of shape resonances in the scattering dynamics.
[1] J. L. Bohn, A. M. Rey, and J. Ye, Cold molecules: Progress in quantum engineering of chemistry and quantum matter, Science 357, 1002 (2017).
[2] S. L. Cornish, M. R. Tarbutt, and K. R. A. Hazzard, “Quantum computation and quantum simulation with ultracold molecules,” Nat. Phys. 20, 730–740 (2024)
[3] N. R. Hutzler, H.-I. Lu, and J. M. Doyle, The buffer gas beam: An intense, cold, and slow source for atoms and molecules, Chemical Reviews, Chemical Reviews 112, 4803 (2012).
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Presenters
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Mateo Londoño
- stony brook university