New types of trilobite-like states in hydrogen atoms and negative ions

In recent years long-range Rydberg molecules, known loosely as ``trilobite" molecules, have become a vibrant research field. We have explored theoretically some variations on the concept of a trilobite molecule. We propose a method to use static field pulses to coherently manipulate a hydrogen Rydberg atom into the same superposition of Rydberg states that composes the trilobite wave function, thus forming a type of chemical bond with a single atom. Optimal control theory and a machine learning algorithm are used to design the appropriate pulse sequences to achieve this. We also show how an analogue of a Rydberg molecule can form in a system composed of a hydrogen negative ion and a nearby neutral atom. The electronic wave function in a doubly excited resonance state in the ``dipole" series of H- extends over a huge spatial volume, similar to a Rydberg wave function. The same Fermi pseudopotential which describes Rydberg molecules leads in this case to short-lived anionic quasi-molecular states, and also could provide a pathway to excite both symmetry-forbidden and very narrow states of H- through the state mixing induced by the perturber.