Towards a test of the Quantum equivalence principle

I will talk about atomic clocks at the interface of quantum theory and gravity, and how they can be used to shed light on tests of the quantum equivalence principle defined in [1], namely a generalization of the ordinary equivalence principle that allows to find a (quantum) locally inertial reference frame even for particles having a quantum state in a superposition of positions.

Specifically, in my thesis I considered an interferometric setup that employs atomic clocks to observe a superposition of gravitational time dilations. I showed that this system can test some features of the quantum equivalence principle, employing the framework of spacetime quantum reference frames [2], namely quantum reference frames associated to particles that have both external and internal degrees of freedom.

Finally, I will talk about how gravitational time dilation enhances some gravity-related measurements performed with this interferometric setup. I quantified the enhancement using some quantum information tools such as Fisher Information and Quantum Fisher Information, that measure the amount of information that probability distributions and quantum states carry about a certain parameter of interest.

[1] F. Giacomini, C. Brukner, Einstein’s Equivalence principle for superpositions of gravitational fields, arXiv: 2012.13754.

[2] F. Giacomini, Spacetime Quantum Reference Frames and superpositions of proper times, arXiv:2101.11628.