# Gravitational Quantum Physics

The regime where general relativity and quantum theory both apply remains vastly unexplored. The major obstacle is lack of experiments: quantum and general relativistic theories have been tested to high precision, but only in separate experiments. This generates fundamental interest in experiments where general relativity and quantum theory would both be necessary to explain the observed phenomena.

Traditional regime to look for quantum and general-relativistic phenomena is high-energy physics. A new approach to addressing this challenge is to focus on low-energy particles but with fast internal dynamics. Internal dynamics can be affected by the relativistic time dilation — or redshift — which depends on the position of the particle in the gravitational field. Several intriguing proposals for experiments have been put forward along these lines, and several theoretical questions were opened in the course of the investigations.

There is a number of Honours and PhD projects available on developing this novel research direction, for example:

- Model an experiment testing how time dilation affects interfering quantum particles;
- Find out how time dilation affects quantum thermometers;
- Develop theory for new tests of the universality of free fall for quantum test-masses;
- Find out the optimal way to test gravity-motivated modifications to quantum mechanics;
- Derive models to test the assumption that time measured even with a quantum clock must be a classical parameter.

Other projects are possible too, for example on the topic of causal relations in gravitational quantum physics.