Artificial quantum

Figure 7.5 (a) Artificial quantum dot architecture showing the confined electron spins, (b) A diamond unit cell showing a NV centre - a nitrogen defect and a carbon vacancy - with an S = 1 electronic spin... 

In effect, the three entities are different gestalt classifications of a fixed assembly of atoms according to the relative positions of their nuclei. Each is then considered to have independent and different sets of quantum states of vibration and rotation—in complete contradiction of what quantum theory would really say about such an assembly of particles. The enumeration of these somewhat artificial "quantum states" of the separate geometric classifications forms the basis for a statistical calculation of rates of... 

Most theoretical treatments of decay consider the time evolution of an initial state tunneling out of single well [81-85]. However, the present-day possibility of designing the potential parameters of artificial quantum systems [61, 86], opens the way to study the issue of decay in more complex potential profiles as exemplified by semiconductor multibarrier systems of finite length which are formed by a succession of alternating barriers and wells [57] and other artificial multibarrier structures as ultracold atomic gases in optical lattices [86]. 

As another example, we consider a double-barrier resonant tunneling system in ID. These artificial quantum systems, formed of semiconductor materials, have been fabricated and studied since the 1970s of last century [61]. Sakaki and co-workers verified experimentally that electrons in sufficiently thin symmetric double-barrier resonant structures exhibit exponential decay [88]. Recent work has examined the conditions for full nonexponential decay in double-barrier resonant systems [56]. Here we want to exemplify the time evolution of the probability density in these systems along the external region using the resonant expansion given by Eq. (121) [89]. 

Shiang J J et al 1998 Cooperative phenomena in artificial solids made from silver quantum dots the importance of classical coupling J. Phys. Chem. 102 3425... 

It is clear that the density matrix formalism renders a considerable simplification of the basis for the quantum theory of many-particle systems. It emphasizes points of essential physical and chemical interests, and it avoids more artificial or conventional ideas, as for instance different types of basic orbitals. The question is, however, whether this formalism can be separated from the wave function idea itself as a fundament. Research on this point is in progress, and one can expect some interesting results within the next few years. 

A mathematical device, the NSS, which can be related to Artificial Intelligence techniques, has been defined and applied in order to solve or reformulate some quantum chemical problems. This symbol is related to computer formulae generation. It has been shown that by means of the use of NSS s many applications of such symbols can be found in mathematics as well as in Mathematical Chemistry in particular. 

Discrete energy levels are to be observed for position (a) as well as for position (b) at exactly the same values, in case (b) somewhat better expressed than in (a). The level spacing is 135 mV. This spectrum clearly identifies the Au55 cluster as a quantum dot in the classical sense, having discrete electronic energy levels, though broader than in an atom, but nevertheless existent. The description of such quantum dots as artificial, big atoms seems indeed to be justified. 

SET events at elevated temperature. Together with the limited number of free electrons, this may lead us to regard them as artificial atoms. This raises fundamental questions about the design of artificial molecules or artificial solids built up from these nanoscale sub-units [37-39]. Remade and Levine reviewed the ideas associated with the use of chemically fabricated quantum dots as building blocks for a new state of matter [40]. 

The fiuid-phase simulation approach with the longest tradition is the simulation of large numbers of the molecules in boxes with artificial periodic boundary conditions. Since quantum chemical calculations typically are unable to treat systems of the required size, the interactions of the molecules have to be represented by classical force fields as a prerequisite for such simulations. Such force fields have analytical expressions for all forces and energies, which depend on the distances, partial charges and types of atoms. Due to the overwhelming importance of the solvent water, an enormous amount of research effort has been spent in the development of good force field representations for water. Many of these water representations have additional interaction sites on the bonds, because the representation by atom-centered charges turned out to be insufficient. Unfortunately it is impossible to spend comparable parameterization work for every other solvent and... 

In representations of electron densities, the presence or lack of boundaries plays a crucial role. A quantum mechanically valid electron density distribution of a molecule cannot have boundaries, nevertheless, artificial electron density representations with actual boundaries provide useful tools of analysis. For these reasons, among the manifold representations of molecular electron densities, manifolds with boundaries play a special role. 

Only for a special class of compound with appropriate planar symmetry is it possible to distinguish between (a) electrons, associated with atomic cores and (7r) electrons delocalized over the molecular surface. The Hiickel approximation is allowed for this limited class only. Since a — 7r separation is nowhere perfect and always somewhat artificial, there is the temptation to extend the Hiickel method also to situations where more pronounced a — ix interaction is expected. It is immediately obvious that a different partitioning would be required for such an extension. The standard HMO partitioning that operates on symmetry grounds, treats only the 7r-electrons quantum mechanically and all a-electrons as part of the classical molecular frame. The alternative is an arbitrary distinction between valence electrons and atomic cores. Schemes have been devised [98, 99] to handle situations where the molecular valence shell consists of either a + n or only a electrons. In either case, the partitioning introduces extra complications. The mathematics of the situation [100] dictates that any abstraction produce disjoint sectors, of which no more than one may be non-classical. In view if the BO approximation already invoked, only the valence sector could be quantum mechanical9. In this case the classical remainder is a set of atomic cores in some unspecified excited state, called the valence state. One complication that arises is that wave functions of the valence electrons depend parametrically on the valence state. 

The paper [8] includes results of investigating electron mechanisms of the impact of active particles, radicals, hydrated electrons artificially generated by plasma on the behavior of cyanide complexes of zinc in water solutions. The above investigation was conducted using quantum chemistry methods. Quantum-chemical calculation of electron structure of the complexes Zn(CN)42 4EP-20H- with complete optimization of all geometric parameters [9] was performed. 

Lefebvre, R. and Moiseyev, N. Artificial resonance procedure for the determination of quantum mechanical rate constants in the tunneling regime, J. Chem. Phys., 93 (1990), 7173-7178... 

The successful design of both natural and artificial molecular photovoltaic devices rests on meeting three fundamental requirements, namely 121 (1) The quantum yield for the charge separation process should be as high as possible. That is, kcs > kd (Figure 1). (2) The lifetime, tcr (= 1 lkcr), of the CS state must be sufficiently long to enable it to carry out... 

Artificial Intelligence Contraction Algorithms in Quantum Dynamics Application to CD3H and... 

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