High-resolution laser resonances of antiprotonic helium in superfluid 4He

Anna Sótér, Hossein Aghai-Khozani, Dániel Barna, Andreas Dax, Luca Venturelli and Masaki Hori ()
Additional contact information
Anna Sótér: Max-Planck-Institut für Quantenoptik
Hossein Aghai-Khozani: Max-Planck-Institut für Quantenoptik
Dániel Barna: CERN
Andreas Dax: CERN
Luca Venturelli: Università di Brescia
Masaki Hori: Max-Planck-Institut für Quantenoptik

Nature, 2022, vol. 603, issue 7901, 411-415

Abstract: Abstract When atoms are placed into liquids, their optical spectral lines corresponding to the electronic transitions are greatly broadened compared to those of single, isolated atoms. This linewidth increase can often reach a factor of more than a million, obscuring spectroscopic structures and preventing high-resolution spectroscopy, even when superfluid helium, which is the most transparent, cold and chemically inert liquid, is used as the host material1–6. Here we show that when an exotic helium atom with a constituent antiproton7–9 is embedded into superfluid helium, its visible-wavelength spectral line retains a sub-gigahertz linewidth. An abrupt reduction in the linewidth of the antiprotonic laser resonance was observed when the liquid surrounding the atom transitioned into the superfluid phase. This resolved the hyperfine structure arising from the spin–spin interaction between the electron and antiproton with a relative spectral resolution of two parts in 106, even though the antiprotonic helium resided in a dense matrix of normal matter atoms. The electron shell of the antiprotonic atom retains a small radius of approximately 40 picometres during the laser excitation7. This implies that other helium atoms containing antinuclei, as well as negatively charged mesons and hyperons that include strange quarks formed in superfluid helium, may be studied by laser spectroscopy with a high spectral resolution, enabling the determination of the particle masses9. The sharp spectral lines may enable the detection of cosmic-ray antiprotons10,11 or searches for antideuterons12 that come to rest in liquid helium targets.

Date: 2022
References: Add references at CitEc
Citations:

Downloads: (external link)
https://www.nature.com/articles/s41586-022-04440-7 Abstract (text/html)
Access to the full text of the articles in this series is restricted.

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:nat:nature:v:603:y:2022:i:7901:d:10.1038_s41586-022-04440-7

Ordering information: This journal article can be ordered from
https://www.nature.com/

DOI: 10.1038/s41586-022-04440-7

Access Statistics for this article

Nature is currently edited by Magdalena Skipper

More articles in Nature from Nature
Bibliographic data for series maintained by Sonal Shukla () and Springer Nature Abstracting and Indexing ().