Hannover 2020 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 42: Ultracold atoms, ions, and BEC V (joint session A/Q)

Q 42.7: Talk

Thursday, March 12, 2020, 12:45–13:00, f303

World’s first atom interferometer with a metastable He BEC — •Oleksiy Onishchenko, Rudolf F. H. J. van der Beek, Kjeld S. E. Eikema, Hendrick L. Bethlem, and Wim Vassen — LaserLaB, Department of Physics and Astronomy, Vrije Universiteit, Amsterdam, the Netherlands

Atom interferometry has established itself as a valuable precision measurement tool for the gravitational potential, the Einstein equivalence principle, and the fine structure constant (α) among other things. While most interferometry experiements with ultracold atoms up to now have been performed with alkali or alkaline-earth atoms, metastable helium (He*) stands apart with unique advantages. Among those are the possibility to do high-accuracy atom number detection on a multichannel plate, a very small second-order Zeeman shift, and a very high critical acceleration and recoil velocity [1]. Those advantages are especially suitable for a high-precision measurement of α in a manner independent of quantum electrodynamics calculations. We experimentally demonstrate a crucial tool for such a measurement with He*, namely a large number of Bloch oscillations in an optical lattice, performed with high efficiency. This technique coherently transfers a well-known quantity of linear momentum to the atoms, which strongly reduces the uncertainty in atom recoil velocity measurements for determining α. We also demonstrate a proof-of-principle Mach-Zehnder interferometer with He*.

[1] W. Vassen et al. “Ultracold metastable helium: Ramsey fringes and atom interferometry”. Appl. Phys. B 122, 289 (2016).