Laser cooling Rydberg molecules -- a detailed study of the helium dimer

Fuente: arXiv
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Main Authors: Verdegay, Lucía, Zeng, Bingcheng, Knapp, Daniel Y., Roth, Jack C., Beyer, Maximilian
Format: Preprint
Published: 2025
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_version_ 1866916749091274752
author Verdegay, Lucía
Zeng, Bingcheng
Knapp, Daniel Y.
Roth, Jack C.
Beyer, Maximilian
author_facet Verdegay, Lucía
Zeng, Bingcheng
Knapp, Daniel Y.
Roth, Jack C.
Beyer, Maximilian
contents The helium dimer in its metastable triplet state is a promising candidate to be the first laser-cooled homonuclear molecule. An ultracold gas of He$_2^*$ would enable a new generation of precision measurements to test quantum electrodynamics for three- and four-electron molecules through Rydberg spectroscopy. Nearly diagonal Franck-Condon factors are obtained because the electron employed for optical cycling occupies a Rydberg orbital that does not take part in the chemical bond. Three possible laser cooling transitions are identified and the spin-rovibronic energy-level structure of the relevant states as well as electronic transition moments, linestrengths, and lifetimes are determined. The production of He$_2^*$ molecules in a supersonic beam is discussed, and a laser slowing scheme to load a magneto-optical trap under such conditions is simulated using a rate equation approach. Various repumping schemes involving one or two upper electronic states are compared to maximize the radiative force. Loss mechanisms such as spin-forbidden transitions, predissociation, and ionization processes are studied and found to not introduce significant challenges for laser cooling and trapping He$_2^*$. The sensitivity of the vibrational levels of He$_2^+$ with respect to the static polarizability of atomic helium is determined and its implications for a new quantum pressure standard are discussed.
format Preprint
id arxiv_https___arxiv_org_abs_2505_14798
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Laser cooling Rydberg molecules -- a detailed study of the helium dimer
Verdegay, Lucía
Zeng, Bingcheng
Knapp, Daniel Y.
Roth, Jack C.
Beyer, Maximilian
Atomic Physics
Chemical Physics
The helium dimer in its metastable triplet state is a promising candidate to be the first laser-cooled homonuclear molecule. An ultracold gas of He$_2^*$ would enable a new generation of precision measurements to test quantum electrodynamics for three- and four-electron molecules through Rydberg spectroscopy. Nearly diagonal Franck-Condon factors are obtained because the electron employed for optical cycling occupies a Rydberg orbital that does not take part in the chemical bond. Three possible laser cooling transitions are identified and the spin-rovibronic energy-level structure of the relevant states as well as electronic transition moments, linestrengths, and lifetimes are determined. The production of He$_2^*$ molecules in a supersonic beam is discussed, and a laser slowing scheme to load a magneto-optical trap under such conditions is simulated using a rate equation approach. Various repumping schemes involving one or two upper electronic states are compared to maximize the radiative force. Loss mechanisms such as spin-forbidden transitions, predissociation, and ionization processes are studied and found to not introduce significant challenges for laser cooling and trapping He$_2^*$. The sensitivity of the vibrational levels of He$_2^+$ with respect to the static polarizability of atomic helium is determined and its implications for a new quantum pressure standard are discussed.
title Laser cooling Rydberg molecules -- a detailed study of the helium dimer
topic Atomic Physics
Chemical Physics
url https://arxiv.org/abs/2505.14798