Research Area B - Quantum Metrology for Tests of Fundamental Physics

The main goal of RA B is the design of quantum-correlated few- and many-body states to enhance the performance of useful measurement instruments, such as clocks and matter-wave interferometers, and to use their improved resolution and sensitivity to explore physics beyond the Standard Model. We will demonstrate the operation of atom interferometers up to 16 dB below the standard quantum limit, and matter-wave interferometers with wave packet separations of metres that are probed for seconds, and demonstrate their usefulness for inertial sensing and in atomic clocks. We will build multi-ensemble optical clocks with inaccuracies better than 10−18 and instabilities approaching 10−17 after 1s integration time, employing correlations to improve the signal-to- noise ratio and to suppress systematic effects. By extending the quantum atom optics toolbox to more exotic systems, such as (anti-)protons, nuclei, and molecules, we will be able to make highly accurate frequency comparisons between novel systems. Accurate spectroscopy of such systems will allow us to improve current bounds on violations of CPT symmetry, on violations of local Lorentz invariance, and on a possible variation of the fine-structure constant α or the electron-to-proton mass ratio μ = me/mp by at least two orders of magnitude, complementing and possibly clarifying astrophysical observations. Furthermore, we will develop a quantum version of the equivalence principle and explore possible non-trivial effects of gravity on extended quantum objects.