Caustics are singularities arising from wave focusing. Examples include rainbows, gravitational lensing, and freak waves. The natural mathematical language for describing caustics is catastrophe theory which predicts that caustics take on certain universal shapes. When applied to classical waves one finds that the singularities seen at large scales are replaced at short scales by smooth...
We study the dynamics of an open quantum system linearly coupled to a bosonic reservoir. We show that, in the ultrastrong coupling limit, the system undergoes a nonselective measurement and then evolves unitarily according to an effective Zeno Hamiltonian. This dynamical process is largely independent of the reservoir state. We examine the entanglement breaking effect of the ultrastrong...
Solutions of the time-dependent Schrödinger equation are mapped to other solutions for a (possibly) different potential by so-called form-preserving transformations. These time-dependent transformations of the space and time coordinates can produce remarkable solutions with surprising properties. A classic example is the force-free accelerating Airy beam found by Berry and Balazs. We review...
