Quantum Delta NL and NWO - Quantum Technology Grant 2023 - Quantum for pressure.

Quantum for pressure - measuring atomic polarizabilities with molecular ions for a quantum pressure gauge

The aim of this project is to develop a novel method to spectroscopically determine the static polarizability of rare gas atoms, with the first application to helium. The atomic polarizability is accessed via the long-range part of the molecular potential of excimer cations like He$_2^+$. Relying on a novel and broadly applicable laser slowing technique, neutral excimer molecules are slowed down to standstill. This will drastically reduce Doppler related effects and allow sufficiently long interaction times to prepare molecules in long-range states. Using Rydberg series extrapolation, intervals between excited vibrational levels in the cation, which are particularly sensitive to the static polarizability, are measured. Narrow bandwidth laser sources referenced to optical frequency combs and atomic clocks and the careful characterization and control of systematic uncertainties will allow an experimental determination of the static polarizability of helium with unprecedented accuracy. Accurate measuring methods for the polarizability of helium and other rare gases are of utmost importance for paving the way for new quantum pressure standards, which became possible after establishing the new international system of units (SI) in 2018. The pressure is related via the gas law to the particle density, which can be measured via monitoring a change in the dielectric constant of a capacitor or the refractive index of light inside a cavity - if an accurate polarizability is known.

Open PhD positions. Please contact m.beyer@vu.nl