Research

While general relativity shows gravity as fundamental to our notions of space and time, physics on the microscopic scale seems to be perfectly described by quantum mechanics and nearly a century of intense research has not been sufficient to reconcile the two theories. The research field of Gravitational Quantum Optics explores the interface of the two theories with a focus on practical applications and laboratory tests. ... read more

Free electrons, for example, the electrons in the beam of an electron microscope, can be manipulated efficiently by electromagnetic fields and interact with other quantum systems through their electric and magnetic near field. These properties can be exploited in Free-Electron Quantum Optics. For example, current-modulation of electron beams can enable coherent control of quantum systems on the nanoscale and promises new spectroscopic techniques. ... read more

Minuscule gravitational effects such as the gravitational field of light, gravitationally mediated entanglement and modifications of the Newtonian force law at short distance could be measured in experiments with quantum sensors. Such experiments can provide important results to further our understanding of gravity itself. ... read more

The gravitational field of relativistic sources, for example, laser pulses and proton bunches in the beam of the Large Hadron Collider (LHC), differs notably from gravitational fields sourced by slow-moving matter and provide insights into the interface of gravity and quantum mechanics. ... read more

Optomechanical systems consist of mechanical elements that interact with light. Due to high control of light researchers have achieved, it is possible to manipulate and monitor the mechanical elements with very high precision and operate these composite systems in the quantum regime. They can be used for various applications ranging from quantum simulation to quantum sensing and even exploration of quantum properties of the gravitational field. ... more here

Ultra-cold atomic gases can be used for various applications ranging from quantum memories and quantum sensors to quantum simulation. When cooled sufficiently, clouds of bosonic atoms form Bose-Einstein condensates with fascinating properties like the existence of phonons, quantized quasiparticles of sound, which can be used for sensing and simulation. ... more here

While it is often argued that 70% of the universe’ energy content is of yet unknown nature, an alternative interpretation of the astrophysical observations is provided by theories based on generalized spacetime geometries. As the geometry of spacetime is indivisibly related to its causal structure, restrictions arise on physically viable modifications of General Relativity.  ... read more

The General Boundary Formulation (GBF) of Quantum Field Theory (QFT) has been constructed for the application to general spacetime regions as a precursor for QFT without pre-defined causal structure and a tool for quantum gravity. ... read more