You will develop theoretical schemes for quantum-enhanced sensing of novel phenomena such as gravitational effects in massive quantum superpositions, as well as the quantum aspects of gravity more generally. Particular emphasis is to be placed on the experimental feasibility of these schemes in interferometric and other setups on optical, mechanical, optomechanical or other platforms. Consequently, it will also develop methods of combating decoherence effects in these schemes, for instance by employing strategies from quantum information science.