Cold trapped molecular ions and hybrid platforms for ions and neutral particles

Recent years have seen the emergence of a new generation of collision and cold-chemistry experiments in which cold atoms and ions are brought into contact in a controlled way in hybrid platforms. Furthermore, new possibilities for the preparation and detection of molecular quantum states with high sensitivity and precision have been demonstrated based on quantum-logic schemes. Here we review experimental progress in the fields of hybrid atom–ion platforms and molecular ions. Our discussion includes the generation and control of motional and internal states of molecular ions, precision spectroscopy, cold collisions between ions and neutral atoms, as well as reactive and inelastic processes. These advances represent important stepping stones for new directions in fundamental research and technological applications across various domains ranging from precision measurements and studies of chemical dynamics to quantum technologies.