Precision spectroscopy in helium (Amsterdam, The Netherlands)

In the physics of light and matter group of the VU university in Amsterdam chair prof. dr. W.M.G. Ubachs) we have two openings for PhD research.

Position 1: Ultracold Helium atoms.
Goal is to accurately measure transition frequencies in helium atoms, laser cooled and trapped in a long-lived metastable state, at a temperature of 1 microKelvin in an optical dipole trap, see our paper in Science, 196 (2011) for a first result. This work aims to improve experimental tests of QED theory of atomic structure, to deduce the nuclear charge radius of the alpha-particle and the helion (the helium-3 nucleus) and to measure the fine structure constant. PI: dr. Wim Vassen

Position 2: Frequency comb spectroscopy.
This project also aims to test QED in helium atoms and ions. In this case excitation is from the ground state of helium and from the ground state of the helium-ion. This requires a frequency comb in the extreme ultraviolet part of the spectrum, which is generated by pulsed amplification and frequency upconversion of a femtosecond frequency comb laser, see PRL 063001 (2010). Excitation of helium atoms will be in a collimated beam, while the helium ion will be excited in an ion trap. PI: prof. dr. Kjeld Eikema Both projects rely on ultrastable lasers to excite atomic transitions and frequency metrology using a femtosecond frequency comb laser, locked to an atomic clock. Both PhD students will also work to build frequency stabilized lasers at the Hz-level.

We are looking for highly motivated students with interest in experimental atomic, molecular and optical physics, preferably with experience in either laser cooling and trapping, cold molecules,atomic and molecular spectroscopy, or related topics. A Diplom (MSc) degree in Physics, Applied Physics or another relevant field is a prerequisite. The positions are standard Dutch 4-year PhD positions, with full salary (up to a maximum of 2,610 euro gross per month).

Applicants should send their CV along with a motivation letter. The positions are immediately available, but the latest starting date is April 2012. Therefore students who will complete their Diplom (MSc) in the coming months are also welcome to apply.

* Wim Vassen
* LaserLaB VU university
* De Boelelaan 1081
* 1081 HV Amsterdam
* E-Mail: w.vassen@vu.nl
* Telephone: +31 20 5987949
* Website: http://www.nat.vu.nl/en/research/physics-light/fundamental-physics-at-the-atomic-scale/