M. Ploszajczak

Dynamics of quantum systems embedded in a continuum

Abstract The relevance of the open quantum system formalism for the description of weakly bound nuclei far from the valley of stability, small droplets of neutral atoms, gas of trapped atoms, open microwave cavities and quantum dots is discussed. We describe nuclear structure and nuclear reaction studies in the shell model embedded in the continuum. This model is an extension of the multiconfigurational shell model including one-particle decay channels. The coupling to multi-particle decay channels, as e.g. in ‘Borromean systems’, is discussed in the alternative formulation of Gamow shell model in the complete Berggren basis. Simple schematical models are used in order to discuss the basic dynamical processes characteristic of open quantum systems. The generic features of these systems in different regimes of multiconfigurational mixing are illustrated by examples of weakly bound atomic nuclei, externally driven atoms and microwave cavities.

Gamow Shell-Model Description of Neutron-Rich Nuclei

This work presents the first continuum shell-model study of weakly bound neutron-rich nuclei involving multiconfiguration mixing. For the single-particle basis, the complex-energy Berggren ensemble representing the bound single-particle states, narrow resonances, and the nonresonant continuum background is taken. Our shell-model Hamiltonian consists of a one-body finite potential and a zero-range residual two-body interaction. It is demonstrated that the residual interaction coupling to the particle continuum is important; in some cases, it can give rise to the binding of a nucleus.

Shell Model in the Complex Energy Plane

This work reviews foundations and applications of the complex-energy continuum shell model that provides a consistent many-body description of bound states, resonances, and scattering states. The model can be considered a quasi-stationary open quantum system extension of the standard configuration interaction approach for well-bound (closed) systems.

Gamow shell-model description of weakly bound and unbound nuclear states

Recently, the shell model in the complex k-plane (the so-called Gamow Shell Model) has been formulated using a complex Berggren ensemble representing bound single-particle states, single-particle resonances, and non-resonant continuum states. In this framework, we shall discuss binding energies and energy spectra of neutron-rich helium and lithium isotopes. The single-particle basis used is that of the Hartree-Fock potential generated self-consistently by the finite-range residual interaction.

Very high spin Strutinsky calculations with a woods-saxon potential

Abstract The deformation energy at very high spins ( I ≈ 30–90) is calculated as a function of the deformation parameters β and γ using the Strutinsky procedure and a Woods-Saxon single particle potential. Even nuclei in the rare earth region are considered. The Woods-Saxon model produces qualitatively the same maxima and minima in the deformation energy as the Nilsson model. However, slight differences in the height or depth or the position of these extrema may give rise to rather different behaviours of the yrast shape as a function of the angular momentum. We verify numerically that for Woods-Saxon potential the Strutinsky smoothed moment of inertia practically assumes the rigid body value, which is used also in the expression for the classical energy. Then we show analytically that this implies an equivalence between the Lund-Warsaw and Dubna-Rossendorf renormalization of the independent particle energy. Possibilities of making the Nilsson potential better suitable for the present type of calculations are discussed.

Two-proton radioactivity

In the first part of this review, experimental results which lead to the discovery of two-proton radioactivity are examined. Beyond two-proton emission from nuclear ground states, we also discuss experimental studies of two-proton emission from excited states populated either by nuclear β decay or by inelastic reactions. In the second part, we review the modern theory of two-proton radioactivity. An outlook on future experimental studies and theoretical developments will conclude this review.

Study of the 7Be(p, γ)8B and 7Li(n, γ)8Li capture reactions using the shell model embedded in the continuum

We apply the realistic shell model which includes the coupling between many-particle (quasi-)bound states and the continuum of one-particle scattering states to the spectroscopy of mirror nuclei:

Anomaly of the moment of inertia in 158Er above the backbending region

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Shell structure of exotic nuclei

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Universal features of the order-parameter fluctuations: reversible and irreversible aggregation

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