Valentin V. Sokolov

Simple mode on a highly excited background: Collective strength and damping in the continuum

Simple states, such as isobaric analog states or giant resonances, embedded into continuum are typical for mesoscopic many-body quantum systems. Due to the coupling to compound states in the same energy range, a simple mode acquires a damping width ({open_quotes}internal{close_quotes} dynamics). When studied experimentally with the aid of various reactions, such states reveal enhanced cross sections in specific channels at corresponding resonance energies ({open_quotes}external{close_quotes} dynamics which include direct decay of a simple mode and decays of intrinsic compound states through their own channels). We consider the interplay between internal and external dynamics using a general formalism of the effective non-Hermitian Hamiltonian and looking at the situation both from the {open_quotes}inside{close_quotes} (strength functions and spreading widths) and from the {open_quotes}outside{close_quotes} (S matrix, cross sections, and delay times). The restoration of isospin purity and the disappearance of the collective strength of giant resonances at high excitation energy are discussed as important particular manifestations of this complex interplay. {copyright} {ital 1997} {ital The American Physical Society}

Time delay correlations in chaotic scattering: random matrix approach

Abstract We study the correlations of time delays in a model of chaotic resonance scattering based on the random matrix approach. Analytical formulae which are valid for an arbitrary number of open channels and arbitrary coupling strength between resonances and channels are obtained by the supersymmetry method. We demonstrate that in the limit of a large number of open channels the time delay correlation function, though being not a Lorentzian, is characterized, similar to that of the scattering matrix, by the gap between the cloud of complex poles of the S -matrix and the real energy axis.

QUANTUM VERSUS CLASSICAL DECAY LAWS IN OPEN CHAOTIC SYSTEMS

We study analytically the time evolution in decaying chaotic systems and discuss in detail the hierarchy of characteristic time scales that appeared in the quasiclassical region. There exist two quantum time scales: the Heisenberg time

Distribution of Proper Delay Times in Quantum Chaotic Scattering: A Crossover from Ideal to Weak Coupling

{t}_{H}

Invariant correlational entropy and complexity of quantum states

and the time

Interfering Doorway States and Giant Resonances. I. Resonance Spectrum and Multipole Strengths

{t}_{q}{=t}_{H}/\sqrt{\ensuremath{\kappa}T}

Complexity of quantum states and reversibility of quantum motion

(with

Is the concept of the non-Hermitian effective Hamiltonian relevant in the case of potential scattering?

\ensuremath{\kappa}\ensuremath{\gg}1

Ballistic electron quantum transport in the presence of a disordered background

and

How well a chaotic quantum system can retain memory of its initial state

T