The numerical challenge associated with the time-dependent approach to the general problem of bi-dimensional quantum - tunneling is discussed and methods towards its application to concrete problems are developed.
The most intuitive and direct way to study proton emission from unbound nuclear states is to start with a proton wave packet localized inside the well of the p-nucleus interacting potential and follow its time evolution by solving numerically the time-dependent Schrödinger equation (TDSE). Then the physical properties of the decaying system can be inferred from its solution. The most important calculable quantities are: the tunneling probability and the decay rate. In the present paper we consider bi-dimensional axially symmetric nuclear shapes, allowing the treatment of both spherical and deformed nuclei. The solution of TDSE is obtained by the Crank-Nicolson method. We discuss also the treatment of numerical boundary conditions, the preparation of the initial wave function as a quasi-stationary state and the calculation of the decay rate using the flux. In application we reveal the influence of the deformation on the decay rate.
The time evolution of single proton quasi-stationary states emitted from axially deformed nuclei is studied by solving numerically the two-dimensional time dependent Schrödinger equation. Angular distributions of emission with respect to the nuclear axis of symmetry are obtained. It is shown that the main escape paths are determined by the quantum numbers of the metastable state, rather than by the deformation of the potential. Combinations of such numerical studies of multidimensional quantum tunneling and angular distribution measurements from oriented deformed nuclei could provide invaluable nuclear structure information and imaging of Nilsson orbitals.
Open-print version of dissertation thesis. This thesis focuses on the relation between the diproton correlation and the two-proton emission with quantum entanglement. For this purpose, I developed a time-dependent three-body (proton-proton-core) model, where one Cooper pair of protons move inside the mean-field potential. The time-dependent calculation based on the three-body model provides an intuitive way to describe the quantum dynamics of the entangled fermionic pair. It has been shown that, by considering the Cooper-pairing correlation in the initial state of the two protons, (i) the experimental 2p-decay width of Be-6 is well reproduced, and (ii) the two protons are emitted mainly as a diproton-like cluster with the spin-singlet configuration in the early stage of the emission. Hence, the two-proton emission can provide an access to the diproton correlation. This thesis presented the first step to theoretically investigate the diproton correlation as well as quantum entanglement in the time-dependent radioactive emission. [NOTE] In this open-print version, several Figures were inevitably eliminated, because of the copyright and/or file-size problems. Several minor corrections have been done, but without changing the scientific discussions, results, and conclusions from the original version in 2014.