The non-Hermitian (NH) formalism of quantum mechanics enables the study of systems and mechanisms, which are very difficult and sometimes even impossible to study using the standard Hermitian quantum mechanics. In the talk, I will give two out of several examples of such systems that I have studied during my PhD. The first is the collision reaction between excited helium and a molecular hydrogen (in its ground state) which results in a Helium atom in its ground electronic state, a molecular hydrogen ion, and a free electron. The rate of this reaction had been measured recently in very cold temperatures (under 0.1k) in the Lab of Ed Narevicius at Weizmann. We were able to reproduce the experimental reaction rate coefficient for this reaction from first principles including the transition from classical to quantum dynamical behavior. The second system is the resonance tunneling process within two coupled quantum wells, on which some electronic devices are based. My theoretical study shows how such devices (so-called resonance tunneling diodes) can be controlled and suppressed by applying a laser field.