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Research group | Experimental Quantum Metrology

Optical frequency doubling cavity to generate UV light at 280 nm for the manipulation of magnesium ions. Photo: PTB Braunschweig

The research activities at the QUEST Institute for Experimental Quantum Metrology revolve around fundamental questions such as: Are the constants of nature actually constant? How accurate are the predictions of physical theories? The variation of fundamental constants predicted by several theories would manifest itself in a shift of atomic and molecular energy levels.

Therefore, these questions can be answered by precision measurements of the internal structure of trapped and laser-cooled ions. Quantum engineering techniques developed for quantum information processing allow the examination of previously inaccessible atoms and molecules with unprecedented accuracy.

Using this “quantum logic spectroscopy”, a highly accurate optical clock based on a single aluminium ion is being developed. A comparison with other accurate clocks allows the detection of a variation in fundamental constants or deviations from Einstein’s theory of relativity. In addition to these laboratory investigations, astrophysical approaches are also supported. Absorption spectra of interstellar clouds are compared with today’s precise quantum logic spectroscopy data to investigate a possible variation of constants on cosmological time scales. These research results will aid in developing a refined theory and therefore an improved understanding of nature.