Cooling of a Zero-Nuclear-Spin Molecular Ion to a Selected Rotational State

Abstract

We demonstrate rotational cooling of the silicon monoxide cation via optical pumping by a spectrally filtered broadband laser. Compared with diatomic hydrides, SiO\+ is more challenging to cool because of its smaller rotational interval. However, the rotational level spacing and large dipole moment of SiO\+ allows direct manipulation by microwaves, and the absence of hyperfine structure in its dominant isotopologue greatly reduces demands for pure quantum state preparation. These features make ${}^{28}$Si${}^{16}$O\+ a good candidate for future applications such as quantum information processing. Cooling to the ground rotational state is achieved on a 100 ms time scale and attains a population of 94(3)\%, with an equivalent temperature $T=0.53(6)$ K. We also describe a novel spectral-filtering approach to cool into arbitrary rotational states and use it to demonstrate a narrow rotational population distribution ($N\pm 1$) around a selected state.

arXiv comment6+2 pages, 4+1 figures; latest version includes supplemental materials

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Cited by in corpus (13)

• Quantum control of molecules for fundamental physics
• Cold trapped molecular ions and hybrid platforms for ions and neutral particles
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• Generation of rotational ground state HD${}^{+}$ ions in an ion trap using a resonance-enhanced threshold photoionization process
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• Features of Molecular Structure Beneficial for Optical Pumping