Quantum Optics Seminar by Konstantin Beyer

Gravitational interactions in nuclear clocks

Atomic clocks offer remarkable precision and the quantum control over a large number of atoms, with steady improvements in both precision and atom number. Here we study the possibility of using a large number of clock atoms to observe their mutual gravitational interaction. We focus on the redshift induced by other clock atoms, including their energy superpositions as sources of gravity, leading to a genuine quantum gravitational interaction between pairs of atoms. Our results show that the clock frequency shift due to mutual gravity will be non-negligible for a mesoscopic number of clock nuclei in future solid-state thorium clocks. Furthermore, we show that preparation of large, entangled states will enable the study of gravitationally induced entanglement of source masses in superposition, offering an alternative to proposals with spatial superpositions of macroscopic masses. Future nuclear clocks could thus reach a regime where gravitational interactions, and even quantum gravitational contributions due to energy superpositions can become relevant, opening a unique route for tests of gravitating quantum source masses beyond the Newtonian limit.