Speaker
Description
Precision measurements of magnetically trapped antihydrogen provides a unique and pow-
erful way to test fundamental symmetries. A cornerstone of the standard model, CPT
symmetry demands that the spectrum of antihydrogen be identical to that of its ordinary
matter counterpart. Of particular interest is the 1S-2S transition which has been mea-
sured in hydrogen[1] with the remarkable relative precision of a few parts in 10 15 , and
promises a particularly elegant and high precision test of CPT symmetry by comparison
to antihydrogen.
In 2016, the ALPHA collaboration made the first observation[2] of the 1S-2S transition
in antihydrogen, and very recently this measurement was drastically improved[3] to reach
a fractional precision of 2 × 10 −12 . The observed frequency in antihydrogen is consistent
with CPT symmetry at the current level of precision.
In this talk, I will present this latest measurement of the 1S-2S transition and introduce
the methods of anti-atom spectroscopy developed by ALPHA. Finally, I will touch on
future improvements needed to take this milestone measurement to the same precision as
its hydrogen counterpart.
[1] Parthey, C.G. et al, Phys. rev. lett. 107, 203001 (2011).
[2] Ahmadi, M. et al, Nature 541, 506-510 (2017).
[3] Ahmadi, M et al, Nature (2018)