Research group Stibor
One of the most fascinating quantum features is the wave-nature of particles. Various exciting matter-wave experiments have been performed in the last decades with all kinds of particles from electrons to atoms to even large molecules. They show the permutable role of light and matter, such as e.g. diffraction of molecular waves on a standing light grating or an atom laser. Our group focuses on the matter-wave of charged particles, electrons and ions. The parameter charge opens up novel scientific perspectives in electron microscopy, Ahoronov-Bohm physics, Coulomb-induced decoherence or novel quantum communication schemes. We curently work on three major topics:
Information transfer by a quantum modulation of electron matter-waves:
Classical signal transmission relies on the modulation of electromagnetic waves. In the recent decades fascinating novel and secure quantum information transfer techniques were discovered and are already commercially available. They use the quantum features of photons. Our approach is to apply the matter-wave nature of electrons for a fundamentally new method of quantum signal transmission. We were able to modulate a signal on an electron matter-wave in an interferometer and transmit a short message. It could also be demonstrated that this method has a high level of security against eavesdropper attacks and that a quantum key distribution protocol can be implemented.
Quantum decoherence by Coulomb-interaction:
Quantum applications rely on long coherence times, meaning that the system stays in a quantum state as long as possible. We study the transition from a quantum to a classical state (the so-called decoherence) induced by the Coulomb interaction. This is performed in an interferometer that prepares free electrons in a quantum superposition state close to a normal-, semi- or superconducting surface. We could compare our measurements to different theoretical decoherence models. The studies have significant applications in quantum information science, surface analysis, electron microscopy and the realization of hybrid quantum systems.
Sensor technologies with electron matter-waves:
The extremely short matter-wavelength of electrons allows the development of sensitive quantum sensors for electromagnetic oscillations and mechanical vibrations. We created such sensors with a biprism electron interferometer, a single atom beam source and a delay line detector. External electromagnetic frequencies or vibrations cause a periodic oscillation of the interference fringe pattern. We established a method to apply the high spatial and temporal single particle resolution of the detector and combine it with a second order correlation and Fourier analysis. It allows to reveal the external frequencies and amplitudes with high accuracy due to their perturbation of the interference.