1S-2S transition frequency measurements in atomic hydrogen N. Kolachevsky MPQ

Hydrogen Theory Frequency comb Mobile fountain clock Optical fiber link Christian Parthey Arthur Matveev Janis Alnis Axel Beyer Nikolai Kolachevsky Randolf Pohl Thomas Udem Theodor Häncsh Tobias Wilken Birgitta Benhardt Ulrich Jents Brett Altschul Michel Abgrall Daniele Rovera Christophe Salomon Philippe Laurent Katharina Predehl Stefan Droste Ronald Holzwarth Harald Schnatz Gesine Grosche Thomas Legero Stefan Weyers The Team

Hydrogen Levels (n = 1, 2) Bohr DiracQED Hyperfine structure

Hydrogen Levels (n = 1, 2) Bohr DiracQED Hyperfine structure

Energy levels Schrödinger: Schrödinger in atomic units: Dirac in atomic units: QED: recoil: finite nuclear size:

Talk by Randolf Pohl, Monday

N. Kolachevsky et al., Opt. Lett. 36, 4299 (2011)

972 nm diode laser with a 20 cm long external resonator and intra-cavity EOM Beat note diode - dye laser Master oscillator 8-photon process => at 972 nm

FP at zero expansion temperature Typical T c is of 50 mHz/s Janis Alnis

FP1-FP2 Allan deviation Thermal noise limit

Fiber Laser I(  )  Hydrogen maser Stabilized optical fiber FP5 Distribution amplifier Wenzel Chain  4  5  5 Wenzel Chain  4  5  5 PLL I(  )  temperature stabilized 1GHz Comb-comb comparison setup 250 MHz system 100 MHz system 1542 nm

Comb-comb comparison: result

In zero magnetic field B: known precisely to be measured (1) Hz Optical measurement of the 2S HFS

Frequency [Hz] Uncertainty [Hz] Averaged interval frequency Line shape / temperature 02 AC Stark shift 01.2 DC Stark shift 1 Magnetic fields 00.5 Total s HFS result N. Kolachevsky et al., PRL 102, (2009) FFK‘2009

C.G. Parthey et al., PRL 107, (2011)

34 LNM-SYRTE, Observatoire de Paris Mobile fountain clock

Thank you for attention! C.G. Parthey et al., PRL 107, (2011)