Double Feature: High Precision Direct Frequency Comb Spectroscopy in UV (M.Sc. Alexey Grinin)

High Precision Direct Frequency Comb Spectroscopy in UV

Datum: 18.06.2019
Uhrzeit: 14:30
Vortragende(r): M.Sc. Alexey Grinin
Emeritus Group Laser Spectroscopy
Ort: Max Planck Institute of Quantum Optics
Raum: Herbert Walther Lecture Hall

In the last two decades frequency combs became an essential tool for spectroscopyexperiments around the world, allowing for simple and convenient referencing of laserswith dierent wavelengths to each other and to radio frequency standards [1]. A numberof other interesting applications in applied spectroscopy, astronomy, quantum informationand other elds are being investigated [2, 3].

One of the rst suggested applications for frequency combs was precision spectroscopy
of two-photon transitions [4]. While being essentially equivalent in terms of excitation
probability and AC Stark shift as a CW laser with the same average power, frequency
combs oer access to UV and DUV wavelengths via second harmonic generation in crystals
and high harmonic generation in gas targets. Additionally a small interaction region is
well suited for trapped atoms and ions experiments and allows for simple characterization
of electric and magnetic elds as well as pressure shifts. However, an additional systematic
frequency shift arises from chirping of the pulses.
I will report on the rst demonstration of the two-photon direct frequency comb spectroscopy
in UV with sub kilohertz uncertainty, discussing advantages and drawbacks of
this technique. Our measurement of the 1S3S transition in hydrogen is second most precise
after the 1S2S transition [5], improving the Rydberg constant and shading light onto
the Proton Radius Puzzle [6].

[1] Th. Udem, R. Holzwarth and T. W. Hnsch, Nature Vol 416, (2002)
[2] Michael J. Thorpe et al,OPTICS EXPRESS 2387, Vol. 16, No. 4, (2008)
[3] Tilo Steinmetz et al, Science Vol 321, (2008)
[4] Y. V. Baklanov and V. P. Chebotayev, Appl. Phys. 12, (1977) 97
[5] A. Matveev et al, Phys. Rev. Lett. 110, (2013) 230801
[6] A. Antognini et al, Science 339, (2013) 417
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