Mega-Dalton Nanoparticles for Interference Experiments

Quantum physics is currently the best-verified theory of nature. Yet, its transition to the familiar world of our daily experience still raises fundamental questions. The deterministic dynamics of massive objects are best described by quantum waves, which can exist in states that appear mutually exclusive on a macroscopic scale. Our classical perception of well-localized particles only emerges upon measurement. This quantum behavior has been observed for electrons, neutrons, atoms, small and large molecules, and even massive clusters. However, it remains an open question how large or complex an object can be before decoherence, collapse, or other effects suppress its observable quantum nature. Quantum interference of massive clusters has also seen remarkable progress in our laboratory at the University of Vienna. Building on this expertise, MegaNICE aims to take the next leap in matter-wave interferometry by exploring slow and cold nanoparticles in the 150 MDa mass range, together with advanced detection schemes. A major challenge is the preparation, control, and detection of such neutral nanoparticles with the velocity, beam brilliance, and stability required for quantum experiments. MegaNICE will close this gap and lay the foundation for a new generation of high-mass quantum interference studies. Within the project, we will develop novel particle sources and detectors that open access to new materials and particle types. This universality is essential for future matter-wave experiments that seek to extend tests of quantum macroscopicity to previously inaccessible mass scales. We will combine expertise from different research communities: high-energy, picosecond laser pulses operated in quasi-continuous mode (500 kHz) will be explored as a compact and controllable alternative to magnetron sputtering sources. The resulting locally high vapor pressures are expected to enable the generation of large and stable clusters with improved size control. A cryogenic environment will be used to demonstrate aerodynamic lensing at low temperatures, achieving particle velocities down to 20 m/s or below. Various mass-selection schemes will be tested across a parameter range that has rarely been studied before. This progress will pave the way for quantum interference experiments at unprecedented mass scales and enable the measurement of ultraviolet and collisional cross sections of mass-selected, isolated, and neutral nanoparticles that have so far remained out of reach. The project will be carried out at the University of Vienna, under the supervision of Dr. Stefan Gerlich and Prof. Markus Arndt.