Phononic quantum sensors for gravity
Bose-Einstein condensates (BECs) are extremely cold Bose gases consisting of a large number of interacting atoms. BECs have quantum properties that can be  exploited perfectly for high precision metrology. The goal of the research project Phononic Quantum Sensors for Gravity (PhoQuS-G) is an extensive analytical and numerical analysis of the use of phonons (quasi-particles of phase and density perturbations) in BECs for high precision sensing of gravitational fields. The project will be built upon a powerful numerical method employed by the host group that enables the description of condensate splitting, trap release and other (strong) changes of the BEC. This method will be combined with an elaborate description of cold Bose gases, incorporating effects of quantum noise and finite temperature and providing access to second order correlation functions of the Bose gas.

The numerical approach will enable the analysis of the most promising parameter regimes and provide a description of the full time-evolution of BECs, including probe state preparation and measurement. Measurement precision will be optimized using methods of quantum metrology.  A clear pathway will be given towards first gravimetry experiments with phonons in BECs. Such experiments can lead to the development of phononic quantum sensors, a very promising quantum technology. High precision sensing of gravitational fields offers a variety of applications - from fundamental research to technological solutions; for example, knowledge about local gravitational fields (geodesy) can be used to map underground infrastructures, find natural resources or ease navigation. As BECs exist on the micrometer scale, precise measurements of gravitational fields on short distances and of very small objects can be implemented far beyond the scales explored to date. This may offer opportunities for new exciting experiments investigating the interface of quantum mechanics and gravity.