ELFT HÍRADÓ

[Szeminárium koordinátor <sem-admin AT szfki.hu>]

SZFI SeminarAkira OzawaMax-Planck-Institute of Quantum Optics, Germany (host: 
Domokos Péter)Frequency combs in the extreme ultraviolet and their 
applicationsTuesday, 8 November 2022, 10:00, KFKI Campus, Bldg. 1, 2nd floor, 
Conference RoomA Frequency comb comprises of mutually phase coherent pulse 
trains generated from a mode-locked pulsed laser, which translates to equally 
spaced narrow peaks in the frequency domain. Nowadays, frequency combs are 
considered essential in the field of frequency metrology. However, their 
spectral coverage is usually limited to the range extending from the visible 
to the infrared wavelengths due to the fundamental difficulty of developing 
stable mode-locked lasers in the ultraviolet region. To overcome this, we 
employ high-order harmonic generation (HHG) to transfer the spectral 
properties of an IR frequency comb to the extreme ultraviolet (XUV) 
wavelengths. This way, optical frequency metrology can be extended into 
unexplored wavelength regions of XUV. One of the important applications is 
high-precision spectroscopy of simple atomic targets. The energy levels of 
hydrogen-like atoms can be precisely described by bound-state quantum 
electrodynamics (QED). The 1S-2S transition of hydrogen-like He+ ion is an 
important XUV spectroscopy target for testing QED. Due to their charge, He+ 
ions can be held near-motionless in the field-free environment of a Paul 
trap, providing ideal conditions for high-precision measurement. Interesting 
higher-order QED corrections scale with large exponents of the nuclear 
charge, which makes this measurement much more sensitive to these 
corrections. In this talk, we show our recent progress on (X)UV frequency 
comb generation and its applications. Our effort toward high-precision 
spectroscopy of the He+ 1S-2S transition will be presented. We also discuss 
future prospects to perform (X)UV frequency metrology with a compact and 
transportable setup. Minden érdeklődőt szívesen látunk! - Everyone is 
welcome to attend.Attila Nagysem-admin AT szfki.hu