PhD/Postdoc positions in Quantum Metrology and Fundamental Physics

In the research group of Quantum Metrology and Laser Applications at LaserLaB, Vrije Universiteit Amsterdam there are several openings for PhD students and Postdocs. The very international group, consisting of some 20 strongly collaborating senior and junior scientists, focuses on precision measurements of atomic and molecular systems, using advanced laser techniques as well as techniques to cool the motion of atoms and molecules. For this they use the joint infrastructure at LaserLaB, with a variety of lasers ranging from ultrastable to ultrafast, connected to atomic clocks and frequency comb lasers. The goals are to test fundamental theories of physics (like Quantum Electrodynamics), to determine fundamental constants (like the proton-electron mass ratio), and to search for physics beyond the Standard Model, such as fifth forces and extra dimensions; see for example Physics beyond the Standard Model from hydrogen spectroscopy J. Mol. Spectr. 320 (2016) 1. The openings are on the following subjects:

1. A molecular clock based on weakly bound states of H2+ held in a radio-frequency trap. Exotic molecular states in the vicinity of the dissociation threshold are state-selectively generated using molecular Rydberg states of H2. The molecular clock will be used to probe physics beyond the Standard Model and nuclear-spin induced symmetry violations. The measured clock transitions and the study of quasi-bound states of H2+ will pave the way for the generation of the first anti-matter molecules H2- and for future tests of CPT symmetry.
   See also: Half-Collision Approach to Cold Chemistry: Shape Resonances, Elastic Scattering, and Radiative Association in the H++H and D++D Collision Systems, Phys. Rev. X 8, 031085 (2018)
   PhD position; Contact person: Dr. Maximilian Beyer, m.beyer@vu.nl, https://nat.vu.nl/~mbeyer/post/jobs/
2. Determination of the proton-electron mass ratio and search for physics beyond the Standard Model in the HD+ molecular ion. The research will be carried out in an existing ion trap setup using ultrastable lasers and radiofrequency sources. As a PhD student or postdoc you will be responsible for the ongoing upgrade of the experiment and its control system, the development of new spectroscopic detection techniques, numerical modelling, acquisition of data and analysis, and interpretation of data in the context of fundamental physical laws.
   See also: Proton-Electron Mass Ratio from Laser Spectroscopy of HD+ at the Part-Per-Trillion Level, Science 369, 1238-1241 (2020)
   PhD and 1 Postdoc position; Contact person: Dr. Jeroen Koelemeij, j.c.j.koelemeij@vu.nl, http://www.few.vu.nl/~koel
3. Provide a new cornerstone in the global search for physics beyond the Standard Model through the first measurement of the 1S-2S transition in a single He+ ion. This enables a new QED test or a determination of the Rydberg constant and the alpha-particle charge radius. The He+ ion is confined and indirectly laser cooled in an advanced planar Paul trap, while Ramsey-comb excitation (recently developed in our lab) will be used for the measurement. This involves an amplified frequency-comb laser and high-harmonic generation to 32 nm.
   See also: Deep-ultraviolet frequency metrology of H2 for tests of molecular quantum theory, Phys. Rev. Lett. 120, 043204 (2018), and our first demonstration of Ramsey-comb spectroscopy combined with high-harmonic generation: Phys. Rev. Lett. 123, 143001 (2019).
   Postdoc position ; Contact person: Prof. Kjeld Eikema, k.s.e.eikema@vu.nl, http://www.few.vu.nl/~kjeld/Positions.html
4. Precision measurement of vibrational transitions in the hydrogen isotopologues HD and HT using highly sensitive and accurate cavity-enhanced techniques, with lasers locked to a frequency comb and atomic clock. Measurements will test QED theory in 4-particle quantum systems and search for deviations thereof targeting physics beyond the Standard Model.
   See also: Determination of the interval between the ground states of para- and ortho-H2, Phys. Rev. Lett. 123, 163002 (2019), and Sub-Doppler frequency metrology in HD for tests of fundamental physics, Phys. Rev. Lett. 120, 153002 (2018)
   PhD position or Postdoc ; Contact person: Prof. Wim Ubachs, w.m.g.ubachs@vu.nl, http://www.few.vu.nl/~wimu
5. The group has also possibilities for 6-9-12 months Masters projects. There are scholarships available to support Masters students.

We look forward to receiving your application including:

• a detailed curriculum vitae
• a list of publications
• a statement of research interests, containing a short description of your background, motivation and skills
• pdf copies of bachelor and master theses (as available)
• list of grades (Bachelor and Master)
• names of two contacts for references

Please send your application to one or more of the contact persons listed above.

A challenging position in a socially involved organization. The salary will be in accordance with university regulations for academic personnel and amounts €2,395 per month during the first year and increases to €3,061 per month during the fourth year, based on a full-time employment for the PhD Positions.
For the Postdoc positions on full-time basis the remuneration amounts to a minimum gross monthly salary of €2,790 (scale 10) and a maximum €4,402 (scale 10), depending on your education and experience.
For both types of vacancies the job profile is based on the university job ranking system and is vacant for at least 0.8 FTE.

The initial employment contract will affect a period of 1 year, with the possibility of extension.

In case of a PhD, after a satisfactory evaluation of the initial appointment, the contract will be extended for a total duration of 4 years.

Additionally, Vrije Universiteit Amsterdam offers excellent fringe benefits and various schemes and regulations to promote a good work/life balance, such as:

• a maximum of 41 days of annual leave based on full-time employment
• 8% holiday allowance and 8.3% end-of-year bonus
• contribution to commuting expenses
• a wide range of sports facilities which staff may use at a modest charge
• discounts on collective insurances (healthcare- and car insurance)

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