Two photon annihilation operators and squeezed vacuum

Inverses of the harmonic oscillator creation and annihilation operators by their actions on the number states are introduced. Three of the two photon annihilation operators, viz., a(sup +/-1)a, aa(sup +/-1), and a(sup 2), have normalizable right eigenstates with nonvanishing eigenvalues. The eigenvalue equation of these operators are discussed and their normalized eigenstates are obtained. The Fock state representation in each case separates into two sets of states, one involving only the even number states while the other involving only the odd number states. It is shown that the even set of eigenstates of the operator a(sup +/-1)a is the customary squeezed vacuum S(sigma) O greater than

Soliton Lattice and Single Soliton Solutions of the Associated Lam\'e and Lam\'e Potentials

We obtain the exact nontopological soliton lattice solutions of the Associated Lam\'e equation in different parameter regimes and compute the corresponding energy for each of these solutions. We show that in specific limits these solutions give rise to nontopological (pulse-like) single solitons, as well as to different types of topological (kink-like) single soliton solutions of the Associated Lam\'e equation. Following Manton, we also compute, as an illustration, the asymptotic interaction energy between these soliton solutions in one particular case. Finally, in specific limits, we deduce the soliton lattices, as well as the topological single soliton solutions of the Lam\'e equation, and also the sine-Gordon soliton solution.Comment: 23 pages, 5 figures. Submitted to J. Math. Phy

Spin polarization control by electric stirring: proposal for a spintronic device

We propose a spintronic device to generate spin polarization in a mesoscopic region by purely electric means. We show that the spin Hall effect in combination with the stirring effect are sufficient to induce measurable spin polarization in a closed geometry. Our device structure does not require the application of magnetic fields, external radiation or ferromagnetic leads, and can be implemented in standard semiconducting materials

Polarized Magnetic Wire Induced by Tunneling Through a Magnetic Impurity

Using the zero mode method we compute the conductance of a wire consisting of a magnetic impurity coupled to two Luttinger liquid leads characterized by the Luttinger exponent $\alpha(\leq 1)$. We find for resonance conditions, in which the Fermi energy of the leads is close to a single particle energy of the impurity, the conductance as a function of temperature is $G \sim \frac{e^2}{h} (T/T_F)^{2(\alpha-2)}$, whereas for off-resonance conditions the conductance is $G \sim \frac{e^2}{h} (T/T_F)^{2(\alpha-1)}$. By applying a gate voltage and/or a magnetic field, one of the spin components can be in resonance while the other is off-resonance causing a strong asymmetry between the spin-up and spin-down conductances.Comment: 8 pages, submitted to PR

Influence of Microgel Packing on Raspberry-Like Heteroaggregate Assembly

We describe the influence of microgel packing on colloidal-phase mediated heteroaggregation using poly(N-isopropylacrylamide) and poly(N-isopropylmethacrylamide) microgels with 1% mol or 5% mol N,N’-methylenebis(acrylamide) cross-linker. This system is uniquely designed to interrogate the influence of microgel structure and stiffness on microgel deformation at a curved interface by elminating the necessity of electrostatic charge pairing. Microgel monomer and cross-linker content is expected to influence deformation at a curved interface. Microgel deformation and swelling were characterized via atomic force microscopy (AFM) and viscometry. A systematic study of colloidal-phase heteroaggregation was performed at varied effective volume fractions with all microgel compositions. Scanning electron microscopy (SEM) and qNano pore translocation experiments are used to asses the microgel coverage on the resultant raspberry-like particles (RLPs). Results reveal that microgel composition has a strong influence on the efficiency (as determined by microgel coverage) of RLP fabrication. The compositional effects appear to be related to the degree of microgel spreading/deformation at the interface, which is coupled to the influence of packing on assembly fidelity. These findings are widely applicable to systems where microgel deformation occurs at a curved interface. We also demonstrate that qNano pore translocation experiments can be used as a high-throughput method to analyze RLP microgel coverage

Understanding Construction Workers’ Risk Decisions Using Cognitive Continuum Theory

The goal of the research presented in this article was to construct a theory about the influence of decision cues on intuitive and deliberative decision-making in high-hazard construction environments. Drawing from Cognitive Continuum Theory, the article specifies a framework for understanding why and how construction workers make decisions that lead to taking or avoiding physical risks when they encounter daily hazards. A secondary aim of the research was to construct a set of hypotheses about how specific decision cues influence whether a worker is more likely to engage their intuitive impulses or to use careful deliberation when responding to a hazard. These hypotheses are described in this article, and the efficacy of the hypotheses was evaluated using cross-tabulations and nonparametric measures of association. While most of the associations between decision cues and decision mode (i.e., intuition or deliberation) identified in this data set were generally modest, none of the associations were statistically zero, thus indicating that further research is warranted based on theoretical grounds. A rigorous program of theory testing is the next logical step to the research, and the article thus concludes with numerous suggestions for extending the research and testing the proposed hypotheses