Narrow-Line Cooling of Erbium and Dysprosium

by Nefeli Ioli Sonnberger

Abstract:

This master thesis focusses on the optical setup of narrow-line cooling of the element erbium and dysprosium in the Er-Dy experiment. The purpose of this project is to cool an atomic cloud by applying narrow-line cooling instead of broad-line cooling, allowing us to achieve even lower temperatures and hence new research. The first part of the thesis deals with a summary of the theoretical basics of narrow-line cooling and the basic properties of the elements Er and Dy. Further, we describe the optical setup needed for narrow-line cooling, which consists of two lasers (741 and 841 nm) and a Stable Laser Systems (SLS) cavity, which is a very crucial part of the project to stabilise the lasers onto the desired frequency to address the correct transitions for narrow-line cooling. The stabilisation of the lasers is thus achieved by the Pound-Drever-Hall (PDH) locking technique. We performed measurements of the PDH signal for both lasers as well as cavity ring-down to characterise the cavity. Moreover, we searched for the transition of erbium according to theoretical values and found a transition, which we characterised by determining the linewidth and the g-factor. With the right transition, we then cooled the atomic cloud and observed how the temperature changes in the xand y-direction to see how efficient we are cooling, and we performed 2D scan measurements measuring the atom number N and the cloud size σx alteration along the x-axis while varying the attenuation between 5 and 20 dB. With these measurements we could also plot a value proportional to the phase space density (PSD) and saw that our atomic cloud was cooled down. However, it should be mentioned that at the time where the measurements were recorded, we did not have sufficient atoms in the trap to have nice results. In addition, although the optical setup has also been built and aligned for dysprosium, no cooling measurements have been performed and analysed.

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Reference:

Narrow-Line Cooling of Erbium and Dysprosium,
Nefeli Ioli Sonnberger,
Master’s Thesis, 2023.

Bibtex Entry:

@article{SonnbergerMSc,
  title = {Narrow-Line Cooling of Erbium and Dysprosium},
  author = {Sonnberger, Nefeli Ioli},
  journal = {Master's Thesis},
  year = {2023},
  month = {Sep},
  abstract = {This master thesis focusses on the optical setup of narrow-line cooling of the
element erbium and dysprosium in the Er-Dy experiment. The purpose of this
project is to cool an atomic cloud by applying narrow-line cooling instead of
broad-line cooling, allowing us to achieve even lower temperatures and hence
new research. The first part of the thesis deals with a summary of the theoretical
basics of narrow-line cooling and the basic properties of the elements
Er and Dy. Further, we describe the optical setup needed for narrow-line
cooling, which consists of two lasers (741 and 841 nm) and a Stable Laser
Systems (SLS) cavity, which is a very crucial part of the project to stabilise
the lasers onto the desired frequency to address the correct transitions for
narrow-line cooling. The stabilisation of the lasers is thus achieved by the
Pound-Drever-Hall (PDH) locking technique. We performed measurements
of the PDH signal for both lasers as well as cavity ring-down to characterise
the cavity. Moreover, we searched for the transition of erbium according to
theoretical values and found a transition, which we characterised by determining
the linewidth and the g-factor. With the right transition, we then
cooled the atomic cloud and observed how the temperature changes in the xand
y-direction to see how efficient we are cooling, and we performed 2D scan
measurements measuring the atom number N and the cloud size σx alteration
along the x-axis while varying the attenuation between 5 and 20 dB. With
these measurements we could also plot a value proportional to the phase space
density (PSD) and saw that our atomic cloud was cooled down. However, it
should be mentioned that at the time where the measurements were recorded,
we did not have sufficient atoms in the trap to have nice results. In addition,
although the optical setup has also been built and aligned for dysprosium, no
cooling measurements have been performed and analysed.},
  url = {https://www.erbium.at/FF/wp-content/uploads/2024/02/Narrow_Line_Cooling_of_Erbium_and_Dysprosium__Master_Thesis__.pdf},
}