Entanglement switch

Let us now switch our attention to the quantum statistical effects and entanglement production for the case of perfect symmetry between the modes (7i = 72 = 7> Ai = A2 = A). In order to obtain general expressions for the variances, we first write them in terms of the boson operators corresponding to the Hamiltonian (lb). We perform the transformations at —> at exp (i (I>j), which restore the previous phase structure of the intracavity interaction and find, quite generally, the variances at some arbitrary quadrature phase angles 0i, 02 as... 

Thus far, studies of coherent optical processes in a PBG have assumed fixed (static) values of the atomic transition frequency [Quang 1997], However, in order to operate quantum logic gates, based on pairwise entanglement of atoms by field-induced dipole-dipole interactions [Brennen 1999 Petrosyan 2002 Opatrny 2003], one should be able to switch the interaction on- and off-, most conveniently by AC Stark-shifts of the transition frequency of one atom relative to the other, thereby changing its detuning from the PBG edge. 

A key factor in the success of the adaptive mechanism is the ability to recreate a tmiform division of air space every time the coat s functionality switches from waterproof to high insulation. The mechanism that enables this is found on the surface of the barbules. Dawson et al. (1999) noticed that tiny hairs, known as cilia, covered the barbules that function as a stick-slip mechanism to keep the barbules entangled and maintains the movement in directions relative to one another to ensure uniformity in creation of air pockets during the coat s function change. 

Figure 3.1 Various molecular structures of shape memory polymers (SMPs). A stable network and a reversible switching transition are the prerequisites for the polymers to show the shape memory effect (SME). The stable network can be molecule entanglement, chemical cross-hnking, crystaUization, and IPN the reversible switching transition can be the crystalUzation/melting transition, vitrification/glass transition, anisotropic/isotropic transition, reversible chemical cross-linking, and association/disassociation of supramolecular structures. Source [22] Reproduced with permission from Elsevier...

Some applications of polypyrrole, such as drug delivery devices, require specific ion transport. Control of the ion transport process requires determination of the identity of the mobile ion, which is complicate by the fact that there are several ions present in the system. Moreover, Shimidzu and co-woiicers [138,139] demonstrated that ion transport in polypyrrole can be modified by the use of polymeric anions as dopants. Miller and Zhou [140] proved that the electrochemical switching of polypyrrole could achieve controlled release of small anions (such as CIO4), while the incorporation of an immobile polyanion (such as polystyrene sulfonate) resulted in cation transport. The polyanions become trapped within the polypyrrole matrix due to their large size and, perhaps more important, their entanglement with the polypyrrole chains. This increases the stability and mechanical strength of polypyrrole and improves electrical conductivity and electroactivity [141,142]. Therefore it has been of significant interest in the polymerization of pyrrole in polyanion electrolyte solutions [143,144]. 

The onset of the gel effect has been defined in terms of a switch from control of termination by segmental diffusion of polymer radicals to control by translational diffusion. Entanglement of polymer radicals can explain kinetic aspects of the polymerization of methyl methacrylate up to the stage where growth is diffusion controlled. Features of high conversion polymerizations of styrene and benzyl methacrylatehave been explained in terms of diffusion control of termination,... 

Structure. Polymer relaxation processes (such as those involving extended segmental motion and chain (dis)entanglement) are manifest only on the longest time scales. Local segmental motion occurs much more rapidly, and may be a prerequisite for ion and neutral species transport. We conclude that redox switching is therefore quite a complex process. 

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