Quantum Gravity

Entangled photons are an excellent resource to investigate the interface between relativity and quantum physics. Photons are not subject to any gravitational force, so that experiments that test the effect of gravity on entanglement lie outside a purely Newtonian description. Furthermore, they only interact weakly with their environment and can be generated and measured with high efficiency.

Supported by the Research Network "Quantum Aspects of Spacetime (TURIS)" we focus on experiments that simultaneously show unique footprints of relativity and quantum mechanics. We generate our quantum states with state-of-the art SPDC and quantum dot sources and let them evolve in large-scale, orientable table-top optical fiber interferometers before detection with superconducting nanowire single photon detectors. Our experiments aim to measure phase shifts on quantum wave functions induced by gravitational potential differences and non-inertial motion.

50-km Fiber Interferometer for Testing Gravitational Signatures in Quantum Interference, 
Yu et al., Phys. Rev. Lett. 136, 110803 (2026).

Quantum interferometry in external gravitational fields,
T.B. Mieling, T. Morling, C. Hilweg, P. Walther, Phys. Rev. A 112, 062211 (2025).

Experimental observation of Earth’s rotation with quantum entanglement,
R. Silvestri, H. Yu, T. Strömberg, C. Hilweg, R.W. Peterson, P. Walther, Sci. Adv.10,eado0215 (2024).

Polarization transport in optical fibers beyond Rytov's law,
T. B. Mieling, M. A. Oancea, Phys. Rev. Research 5, 023140 (2023).

Measuring space-time curvature using maximally path-entangled quantum states,
T.B. Mieling, C. Hilweg, P. Walther, Phys. Rev. A 106, L031701 (2022).

Limits and prospects for long-baseline optical fiber interferometry,
C. Hilweg, D. Shadmany, P. Walther, N. Mavalvala, and V. Sudhir, Optica 9, 1238-1252 (2022).

Gravitationally induced phase shift on a single photon,
C. Hilweg, F.  Massa, D. Martynov, N. Mavalvala, P. Chrusciel, P. Walther, New Journal of Physics 19, 033028 (2017).