Several standard arguments which attempt to show that the wave function and its derivative must be continuous across jump discontinuities of the potential are reviewed and their defects discusssed. Three arguments which it is hoped are more satisfactory are then presented.
Abstract: Quantum theory does not require the existence of discontinuities: neither in time (quantum jumps), nor in space (particles), nor in spacetime (quantum events). These apparent discontinuities are readily described objectively by the continuous process of decoherence occurring locally on a very short time scale according to the Schrdinger equation for interacting systems, while the observerÕs Ôincrease of informationÕ is appropriately represented by the resulting dynamical decoupling of the corresponding components of the global wave function. Physics Letters A172, 189 (1993) 2As far as is known, all properties of closed quantum systems are perfectly described by means of wave functions in configuration space (in general, wave functionals of certain fields) dynamically evolving smoothly according to the time-dependent Schrdinger equation. However, the condition of being closed (or shielded against interactions with the environment) can easily be estimated to be quite exceptional. It characterizes very special (usually atomic) systems from which the laws of quantum mechanics were derived. When the shielding ceases, most notably during measurements, discontinuous
Via the hydrodynamical formulation of quantum mechanics, we propose new boundary conditions to the problem of tunneling through sharp-edged potential barriers with and without dissipation. Above all, these boundary conditions can be matched without assuming continuity of the wave function at a surface σ where the potential undergoes a finite jump. Our approach yields a general expression for transmission probability from which tunneling with and without dissipation can be directly correlated to standard discussions found in textbooks.