XUV frequency comb metrology on the ground state of helium

Physics – Atomic Physics

Scientific paper

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

18 pages, 13 figures

Scientific paper

10.1103/PhysRevA.84.062512

The operation of a frequency comb at extreme ultraviolet (XUV) wavelengths based on pair-wise amplification and nonlinear upconversion to the 15th harmonic of pulses from a frequency comb laser in the near-infrared range is reported. Following a first account of the experiment [Kandula et al., Phys. Rev. Lett. 105, 063001 (2010)], an extensive review is given of the demonstration that the resulting spectrum at 51 nm is fully phase coherent and can be applied to precision metrology. The pulses are used in a scheme of direct-frequency-comb excitation of helium atoms from the ground state to the 1s4p and 1s5p 1P_1 states. Laser ionization by auxiliary 1064 nm pulses is used to detect the excited state population, resulting in a cosine-like signal as a function of the repetition rate of the frequency comb with a modulation contrast of up to 55%. Analysis of the visibility of this comb structure yields an estimated timing jitter between the two upconverted comb laser pulses of 50 attoseconds, whch indicates that extension to even shorter wavelengths should be feasible. The helium metrology investigation results in transition frequencies of 5740806993(10) MHz and 5814248672(6) MHz for excitation of the 1s4p and 1s5p 1P_1 states, respectively. This constitutes the first absolute frequency measurement in the XUV, attaining unprecedented accuracy in this windowless part of the electromagnetic spectrum. From the measured transition frequencies an eight-fold improved 4He ionization energy of 5945204212(6) MHz is derived. Also a new value for the 4He ground state Lamb shift is found of 41247(6) MHz. This experimental value is in agreement with recent theoretical calculations up to order m\alpha^6 and m^2/(M\alpha^5), but with a six times higher precision, therewith providing a stringent test of quantum electrodynamics in bound two-electron systems.

No associations

LandOfFree

Say what you really think

Search LandOfFree.com for scientists and scientific papers. Rate them and share your experience with other people.

Rating

XUV frequency comb metrology on the ground state of helium does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with XUV frequency comb metrology on the ground state of helium, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and XUV frequency comb metrology on the ground state of helium will most certainly appreciate the feedback.

Rate now

     

Profile ID: LFWR-SCP-O-672179

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.