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Ultrafast Laser Physics and Precision Metrology For Fundamental Tests

Jobs / Positions
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Jobs: 1 Postdoc position: not available anymore

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This position has been filled and is no longer available.

Position: Postdoc on 1S-2S spectroscopy of trapped He+ (and possibly H2 spectroscopy) for fundamental tests.
Funded by NWO and ERC.

This postdoc position is available at the experiment where we want to excite the 1S-2S transition in a single He+ ion. This ion will be trapped in an advanced Paul trap (a collaboration with PTB, the groups of prof. Mehlstaubler and prof Schmidt), and we will excite the two-photon transition with a combination of 32 nm made by High-Harmonic Generation (HHG) and 790 nm (the high-power fundamental wavelength used for HHG). We employ Ramsey-comb spectroscopy, which was developed in our group. The whole experiment involves many techniques, such as a frequency comb laser, high-power parametric laser pulse amplification, an ultra-stable laser, laser cooling at 313 nm, side-band cooling, ultra-high vacuum, quantum-optics, high-harmonic generation, and so much more! We have quite unconventional ideas how to realize the first excitation of He+ from the ground state. The target accuracy is 1 kHz or better. We want to use the measurement to check the predictions by theory, and look for new physics. This is done by comparing the results with other determinations, e.g. in atomic hydrogen, muonic hydrogen, and muonic helium+. This will able us to check the value of the Rydberg constant (it shifted more than 5 sigma in the CODATA 2018 evaluation!), the charge radius of the alpha particle, and test higher-order QED.
Apart from the He+ experiment, there is also the possibility to work on excitation of the EF-X transition of para and ortho H2 (at 202 nm) to determine its dissociation energy for a comparison with theory (a test of quantum-molecular calculations and QED).
You can read more about the He+ experiment here, and about the H2 experiment here.

Below: the High-Harmonic Generation and excitation setup for He+ spectroscopy (in a configuration for a precursor experiment with Xe).


Applicants for the Postdoc position:
You should have a PhD in physics with optics/spectroscopy experience and preferably with Paul-trap experience. You should enjoy challenges and be enthusiastic about this intriguing project. The project is a real team effort, so you should feel comfortable working with 2 PhD students and 1-2 postdocs on this project. Even if you have no experience with Paul traps for precision spectroscopy, you can still apply! Most important is that you are bright, enthusiastic, work well in a team, and are eager to learn.
More information about salary will be posted shortly, but it is the usual salary for a Postdoc in the Netherlands at a university.

Below: Former PhD student Laura Dreissen working in the He+/Xe setup, installing a time-of-flight mass spectrometer for the experiment where we demonstrated a key ingredient of the upcoming He+ experiment: Ramsey-comb spectroscopy with light produced by High-Harmonic generation. The results where published in Phys. Rev. Lett. (2019), and Phys. Rev. A. (2020).

Xe/He+ setup

General conditions of employment

You can find information about the side benefits at www.workingatvu.nl.

The project and position is based in the LaserLaB Vrije Universiteit Amsterdam:
The Vrije Universiteit Amsterdam is a leading, innovative and growing university that is at the heart of society and actively contributes to new developments in teaching and research. Our university has ten faculties which span a wide range of disciplines, as well as several institutes, foundations, research centers, and support services. Its campus is located in the fastest-growing economic region in the Netherlands (the Zuidas district of Amsterdam), and provides work for over 4,500 staff and scientific education for more than 23,000 students.

The application deadline is 1 December 2020.
Evaluations take place continuously, but as long as this message is visible, the position is still open.
Send your application to prof. dr. Kjeld Eikema, email: k.s.e.eikema@vu.nl.
Please include a letter of motivation, CV, and 2 names with email addresses of people as a reference.