Derya Taray
Mai 16th 2022
Direct Frequency Comb
Spectroscopy
of the
Hydrogen 1S – 3S transition
D. Taray PSAS 2022
Hydrogen Precision
Spectroscopy
𝐸𝑛𝑙𝑗 = −𝑅𝑦
𝑚𝑒
1
𝐶𝑁𝑆 2
− 𝑓𝑛𝑙𝑗 α,
, … − δ𝑙,0 3 𝑟𝑁
2
𝑚𝑝
𝑛
𝑛
D. Taray PSAS 2022
Proton charge radius
puzzle
D. Taray PSAS 2022
1S–2S: CG Parthey et al. PRL 107, 203001, 2011
CODATA 2014: J. Phys. Chem. Ref. Data 45, 043102 (2016);
CODATA 2018: J. Phys. Chem. Ref. Data 50, 033105 (2021);
1S – 3S Spectroscopy
3S
3P
3D
656nm
2S
2P
2x205nm
1S
D. Taray PSAS 2022
𝛾1𝑠3𝑠 = 1.005𝑀𝐻𝑧
Outline
1.
2.
3.
4.
Two Photon Direct Frequency Comb Spectroscopy
Experimental Setup
Recent Results: The Hydrogen measurement
The AC-Stark shift discrepancy
D. Taray PSAS 2022
Outline
1.
2.
3.
4.
Two Photon Direct Frequency Comb Spectroscopy
Experimental Setup
Recent Results: The Hydrogen measurement
The AC-Stark shift discrepancy
D. Taray PSAS 2022
Frequency domain
ν1s−3s
𝟐
150 GHz
205nm
Teets, R. et al. PRL 38, 760–764 (1977)
Baklanov, Ye.V et al. Appl. Phys. 12, 97–99 (1977). 9, 31, 104
D. Taray PSAS 2022
Time domain
•
•
•
•
high Intensities for SHG
inherently doppler free
small interaction region (PCV)
normalization signal
• same excitation rate as CW
• same AC Stark shift as CW
7K
1S – 3S
Doppler
free
D. Taray PSAS 2022
1S - 3D
Doppler
broadenend
Outline
1.
2.
3.
4.
Two Photon Direct Frequency Comb Spectroscopy
Experimental Setup
Recent Results: The Hydrogen measurement
The AC-Stark shift discrepancy
D. Taray PSAS 2022
Laser system
Ti:Sa
2W, 820nm
2x SHG 50mW, 205nm
PLL
ECDL
fset
ωrep
νECDL
νECDL
ν1s3s /8
D. Taray PSAS 2022
Enhancement Cavity
Doppler broadenend signal
Doppler free signal
D. Taray PSAS 2022
Detector
D. Taray PSAS 2022
Outline
1.
2.
3.
4.
Two Photon Direct Frequency Comb Spectroscopy
Experimental Setup
Recent Results: The Hydrogen measurement
The AC-Stark shift discrepancy
D. Taray PSAS 2022
Hydrogen measurement
Grinin et al., Science 370, 1061-1066 (2020)
f1S–3S(F=1) = 2 922 742 936 716.68(72)kHz
D. Taray PSAS 2022
Proton Size Puzzle
D. Taray PSAS 2022
Error budget
AC-Stark shift Puzzle
D. Taray PSAS 2022
Systematic Line Shifts
• SOD
• CIFODS
• Pressure Shift
• AC Stark Shift
D. Taray PSAS 2022
Global Fit
D. Taray PSAS 2022
Outline
1.
2.
3.
4.
Two Photon Direct Frequency Comb Spectroscopy
Experimental Setup
Recent Results: The Hydrogen measurement
The AC-Stark shift discrepancy
D. Taray PSAS 2022
Global Fit
f0
H measured -0.57(55)kHz
H modeled
-
κDS
-0.0437(43)
-0.043
κSOD
κAC
-315(25) Hz/K 139.7(9.1)Hz/μW
-315 Hz/K
33 Hz/μW
used in Extrapolation
D. Taray PSAS 2022
κPS
0.58(22)kHz
-
AC-Stark Shift
T2
𝑃𝑜𝑢𝑡
w0 = 80μm
d = c / frep
D. Taray PSAS 2022
r = 500mm
Global Fit
Hydrogen
H modeled
Hydrogen
D
preliminary
f0
-0.57(55)kHz
f0
-0.57(55)Hz
-14.5(1.1)kHz
κDS
-0.0437(43)
κDS
-0.043
-0.0437(43)
-0.1005(84)
κSOD
κAC
-315(25) Hz/K 139.7(9.1)Hz/μW
κSOD
κAC
-315 Hz/K
33 Hz/μW
-315(25) Hz/K 139.7(9.1)Hz/μW
-134(10)Hz/K 208(43) Hz/μW
D. Taray PSAS 2022
κPS
0.58(22)kHz
κPS
0.58(22)kHz
-0.20(37)kHz
AC – Stark shift
Possible Explanations
• Mirror degradation causing frequency dependant reflectivity
• patch charges from stray UV light
• other parameters that coincidentally drift with laser power
To Do:
• Intentionally vary laser power and characterize AC – Stark shift
• Measure possible mirror degradation
D. Taray PSAS 2022
Summary
•
•
•
•
•
Direct frequency comb spectroscopy of Hydrogen
Experiment setup
Hydrogen measurement
AC–Stark shift discrepancy
Outlook: Deuterium measurement
D. Taray PSAS 2022
The Hydrogen Team
Alexey Grinin
Derya Taray
Lothar Maisenbacher
Arthur Matveev
Dylan Yost
Vitaly Wirthl
Randolf Pohl
D. Taray PSAS 2022
Vincent Weis
Thomas Udem
Theodor W. Hänsch
Florian Egli