Entanglement generation and transfer between remote atomic qubits interacting with squeezed field

A pair of two level atoms A1A2, prepared either in a separable state or in an entangled state, interacts with a single mode of two mode squeezed cavity field while a third atomic qubit B interacts with the second mode of the squeezed field in a remote cavity. We analyze, numerically, the generation, sudden death and revival of three qubit entanglement as a function of initial entanglement of qubits A1A2 and degree of squeezing of electromagnetic field. Global negativity of partially transposed state operator is used to quantify the entanglement of three atom state. It is found that the initial entanglement of two mode field as well as that of the pair A1A2, both, contribute to three atom entanglement. A maximally entangled single excitation Bell pair in first cavity and two mode field with squeeze parameter s=0.64 are the initial conditions that optimize the peak value of three qubit mixed state entanglement. A smaller value of s=0.4 under similar conditions is found to generate a three qubit mixed state with comparable entanglement dynamics free from entanglement sudden death.Comment: 14 pages, 7 figures, sections III and IV merged with section II and analytic expressions moved to Appendices A and B. Figures improved and corrected typo

A comparison of the extended x-ray absorption fine structure of nanocrystalline ZrO2 prepared by high-energy ball milling and other methods

We report the results of an extended x-ray absorption fine structure (EXAFS) study of a sample of ZrO2 prepared by high-energy ball milling. X-ray diffraction showed that the sample contained nanocrystals that were predominantly monoclinic with a particle size of 15 nm. The EXAFS for the sample was strongly attenuated in comparison to that for bulk monoclinic ZrO2. This has been interpreted as the ball-milled sample containing a large level of disorder whose possible origins are discussed. In contrast, our previous EXAFS studies of nanocrystalline oxides prepared by sol-gel methods have shown that these samples contain well-ordered crystallites with grain boundaries similar to those in bulk materials. It is concluded that ball-milled samples are very different from oxide nanocrystals produced by other techniques

The stabilization of metal oxide nanocrystals by the addition of alumina

A problem in the study of nanoparticles is that they will tend to grow at moderate temperatures. For example, most oxides (e.g. SnO2, ZrO2, MgO) will show significant grain growth at 400degreesC. This severely limits experimental studies that require measurements over an extensive temperature range. In this contribution we demonstrate that the incorporation of Al2O3 can significantly restrict grain growth in MgO and ZrO2 even at high temperatures