Description:

Abstract: A nuclear optical clock based on a single 229Th ion is expected to achieve a
higher accuracy than the best atomic clocks operational today [1]. Although already
proposed back in 2003 [2], this nuclear clock has not yet become reality.
The main obstacle that has so far hindered the development of a nuclear clock
was an unprecise knowledge of the energy value of a nuclear excited state of the
229Th nucleus, generally known as the 229Th isomer. This metastable nuclear
excited state is the one of lowest energy in whole nuclear landscape and - with an
energy of less than 10 eV - allows for direct nuclear laser excitation, which poses
a central requirement for the development of a nuclear clock.
In the past few years significant progress toward the development of a nuclear
clock has been made: Starting with a first direct detection of the 229Th isomer in
2016 based on its internal conversion decay channel [3], the isomeric lifetime could
be determined in 2017 [4], followed by a first laser-spectroscopic characterization
in 2018 [5]. Most recently a first energy determination based on the isomer’s direct
detection was successful [6], thereby constraining the isomeric energy value
to sufficient precision to determine the laser technology required in the nuclear
clock concept and paving the way for first nuclear laser spectroscopy experiments
[7].
In the presentation I will give an overview over the current status of the nuclear
clock development, with a particular focus on the most recent progress. Also the
next required steps will be detailed and future perspectives will be given.

References
[1] C.J. Campbell et al., Phys. Rev. Lett. 108, 120802 (2012).
[2] E. Peik, C. Tamm, Eur. Phys. Lett. 61, 181 (2003).
[3] L. von der Wense et al., Nature 533, 47 (2016).
[4] B. Seiferle et al., Phys. Rev. Lett. 118, 042501 (2017).
[5] J. Thielking et al., Nature 556, 321 (2018).
[6] B. Seiferle et al., Nature 573, 243 (2019).
[7] L. von der Wense, C. Zhang, arXiv:1905.08060 (2019).

Speaker: Lars von der Wense, JILA

Host: CFP

Keywords: Physics, CFP, Colloquium