Observation of the Hyperfine Spectrum of Antihydrogen

Authors

M. Ahmadi, University of LiverpoolFollow
B. X. R. Alves, Aarhus UniversityFollow
C. J. Baker, Swansea UniversityFollow
W. Bertsche, University of ManchesterFollow
E. Butler, CERN
A. Capra, TRIUMF
C. Carruth, University of California - Berkeley
C. L. Cesar, Universidade Federal do Rio de JaneiroFollow
M. Charlton, Swansea UniversityFollow
S. Cohen, Ben-Gurion University of the Negev
R. Collister, TRIUMFFollow
S. Eriksson, Swansea UniversityFollow
A. Evans, University of Calgary
N. Evetts, University of British Columbia - VancouverFollow
J. Fajans, University of California - Berkeley
T. Friesen, Aarhus UniversityFollow
M. C. Fujiwara, TRIUMFFollow
D. R. Gill, TRIUMFFollow
A. Gutierrez, University College London
J. S. Hangst, Aarhus UniversityFollow
W. N. Hardy, University of British ColumbiaFollow
M. E. Hayden, Simon Fraser UniversityFollow
C. A. Isaac, Swansea UniversityFollow
A. Ishida, University of Tokyo
M. A. Johnson, University of ManchesterFollow
S. A. Jones, Swansea UniversityFollow
S. Jonsell, Stockholm University
L. Kurchaninov, TRIUMF
N. Madsen, Swansea University
M. Mathers, York University
D. Maxwell, Swansea University
J. T. K. McKenna, TRIUMFFollow
S. Menary, York University
J. M. Michan, TRIUMFFollow
T. Momose, University of British Columbia - VancouverFollow
J. J. Munich, Simon Fraser UniversityFollow
P. Nolan, University of Liverpool
K. Olchanski, TRIUMF
A. Olin, TRIUMFFollow
P. Pusa, University of Liverpool
C. O. Rasmussen, Aarhus UniversityFollow
F. Robicheaux, Purdue University
R. L. Sacramento, Universidade Federal do Rio de JaneiroFollow
M. Sameed, Swansea UniversityFollow
E. Sarid, Soreq NRCFollow
D. M. Silveira, Universidade Federal do Rio de JaneiroFollow
S. Stracka, TRIUMF
G. Stutter, Aarhus University
C. So, University of Calgary
Timothy Tharp, Marquette UniversityFollow
J. E. Thompson, York University
R. I. Thompson, University of CalgaryFollow
D. P. van der Werf, Swansea UniversityFollow
J. S. Wurtele, University of California - BerkeleyFollow

Document Type

Article

Language

eng

Publication Date

8-3-2017

Publisher

Nature Publishing Group

Source Publication

Nature

Source ISSN

0028-0836

Abstract

The observation of hyperfine structure in atomic hydrogen by Rabi and co-workers^1,2,3 and the measurement⁴ of the zero-field ground-state splitting at the level of seven parts in 10¹³ are important achievements of mid-twentieth-century physics. The work that led to these achievements also provided the first evidence for the anomalous magnetic moment of the electron^5,6,7,8, inspired Schwinger’s relativistic theory of quantum electrodynamics^9,10 and gave rise to the hydrogen maser¹¹, which is a critical component of modern navigation, geo-positioning and very-long-baseline interferometry systems. Research at the Antiproton Decelerator at CERN by the ALPHA collaboration extends these enquiries into the antimatter sector. Recently, tools have been developed that enable studies of the hyperfine structure of antihydrogen¹²—the antimatter counterpart of hydrogen. The goal of such studies is to search for any differences that might exist between this archetypal pair of atoms, and thereby to test the fundamental principles on which quantum field theory is constructed. Magnetic trapping of antihydrogen atoms^13,14 provides a means of studying them by combining electromagnetic interaction with detection techniques that are unique to antimatter^12,15. Here we report the results of a microwave spectroscopy experiment in which we probe the response of antihydrogen over a controlled range of frequencies. The data reveal clear and distinct signatures of two allowed transitions, from which we obtain a direct, magnetic-field-independent measurement of the hyperfine splitting. From a set of trials involving 194 detected atoms, we determine a splitting of 1,420.4 ± 0.5 megahertz, consistent with expectations for atomic hydrogen at the level of four parts in 10⁴. This observation of the detailed behaviour of a quantum transition in an atom of antihydrogen exemplifies tests of fundamental symmetries such as charge–parity–time in antimatter, and the techniques developed here will enable more-precise such tests.

Comments

Published version. Nature, Vol. 548 (August 3, 2017): 66-69. DOI. This work is licensed under a Creative Commons Attribution 4.0 International (CC BY 4.0) licence. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons licence, users will need to obtain permission from the licence holder to reproduce the material. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.

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An Erratum to this article was published on 20 December 2017

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.

Recommended Citation

Ahmadi, M.; Alves, B. X. R.; Baker, C. J.; Bertsche, W.; Butler, E.; Capra, A.; Carruth, C.; Cesar, C. L.; Charlton, M.; Cohen, S.; Collister, R.; Eriksson, S.; Evans, A.; Evetts, N.; Fajans, J.; Friesen, T.; Fujiwara, M. C.; Gill, D. R.; Gutierrez, A.; Hangst, J. S.; Hardy, W. N.; Hayden, M. E.; Isaac, C. A.; Ishida, A.; Johnson, M. A.; Jones, S. A.; Jonsell, S.; Kurchaninov, L.; Madsen, N.; Mathers, M.; Maxwell, D.; McKenna, J. T. K.; Menary, S.; Michan, J. M.; Momose, T.; Munich, J. J.; Nolan, P.; Olchanski, K.; Olin, A.; Pusa, P.; Rasmussen, C. O.; Robicheaux, F.; Sacramento, R. L.; Sameed, M.; Sarid, E.; Silveira, D. M.; Stracka, S.; Stutter, G.; So, C.; Tharp, Timothy; Thompson, J. E.; Thompson, R. I.; van der Werf, D. P.; and Wurtele, J. S., "Observation of the Hyperfine Spectrum of Antihydrogen" (2017). Physics Faculty Research and Publications. 162.
https://epublications.marquette.edu/physics_fac/162