New Quasi-Atomic Nanoheterostructures: Superatoms and Excitonic Quasi-Molecules

In this review, the state-of-the-art of research of artificial atoms (superatoms or quasi-atomic nanoheterostructures) and more complex nanostructures based on them—synthetic molecules is discussed, a new model of an artificial atom, which satisfactorily explains its electronic properties, is proposed, and the prospects for development of the new scientific trend are mentioned.В этом обзоре обсуждается современное состояние исследований искусственных атомов (сверхатомов или квазиатомных наногетероструктур) и более сложных наноструктур на их основе — синтетических молекул, предложена новая модель искусственного атома, удовлетворительно объясняющая его электронные свойства, а также указаны перспективы для развития нового научного направления.В цьому огляді обговорюється сучасний стан досліджень штучних атомів (надатомів або квазиатомових наногетероструктур) і більш складних наноструктур на їх основі — синтетичних молекул, запропоновано новий модель штучного атома, що задовільно пояснює його електронні властивості, а також зазначено перспективи для розвитку нового наукового напряму

Periodic features in the Dynamic Structure Factor of the Quasiperiodic Period-doubling Lattice

We present an exact real-space renormalization group (RSRG) method for evaluating the dynamic structure factor of an infinite one-dimensional quasiperiodic period-doubling (PD) lattice. We observe that for every normal mode frequency of the chain, the dynamic structure factor $S(q,\omega)$ always exhibits periodicity with respect to the wave vector $q$ and the presence of such periodicity even in absence of translational invariance in the system is quite surprising. Our analysis shows that this periodicity in $S(q,\omega)$ actually indicates the presence of delocalized phonon modes in the PD chain. The Brillouin Zones of the lattice are found to have a hierarchical structure and the dispersion relation gives both the acoustic as well as optical branches. The phonon dispersion curves have a nested structure and we have shown that it is actually the superposition of the dispersion curves of an infinite set of periodic lattices.Comment: 9 pages, 3 postscript figures, REVTeX, To appear in Phys. Rev. B (1 February 1998-I

Excitonic quasimolecule consisting of two semiconductor quantum dots

The effect of a significant increase in the binding energy of the singlet ground state of an excitonic quasimolecule consisting of two CdS quantum dots, in comparison with the binding energy of a biexciton in a single crystal of CdS (almost by two orders of magnitude), has been found

Model of Qubit in Multi-Electron Quantum Dot

The discussion of qubit for quantum computation in quantum dots technology is presented. The state-of-the-art structure of multi-electron dot is considered and the appropriate quasi-two-level system is suggested employing the singlet-triplet transition in the presence of magnetic field. The methods of qubit rotation (the write procedure) as well as two-qubit operations, as controlled-NOT, in vertically stacked dots system are analysed