Relation between directed polymers in random media and random bond dimer models

We reassess the relation between classical lattice dimer models and the continuum elastic description of a lattice of fluctuating polymers. In the absence of randomness we determine the density and line tension of the polymers in terms of the bond weights of hard-core dimers on the square and the hexagonal lattice. For the latter, we demonstrate the equivalence of the canonical ensemble for the dimer model and the grand-canonical description for polymers by performing explicitly the continuum limit. Using this equivalence for the random bond dimer model on a square lattice, we resolve a previously observed discrepancy between numerical results for the random dimer model and a replica approach for polymers in random media. Further potential applications of the equivalence are briefly discussed.Comment: 6 pages, 3 figure

Optimality of feedback control for qubit purification under inefficient measurement

A quantum system may be purified, i.e., projected into a pure state, faster if one applies feedback operations during the measurement process. However, the existing results suggest that such an enhancement is only possible when the measurement efficiency exceeds 0.5, which is difficult to achieve experimentally. We address the task of finding the global optimal feedback control for purifying a single qubit in the presence of measurement inefficiency. We use the Bloch vector length, a more physical and practical quantity than purity, to assess the quality of the state, and employ a backward-iteration algorithm to find the globally optimal strategy. Our results show that a speedup is available for quantum efficiencies well below 0.5, which opens the possibility of experimental implementation in existing systems

Are Investors Warned by Disclosure of Conflicts of Interest? The Moderating Effect of Investment Horizon

Financial analysts are required to disclose conflicts of interest (COI) in their research reports, but there is limited evidence on the effectiveness of COI disclosures. We investigate whether the influence of disclosing COI in analyst reports on investors' decision making depends on investment horizon. Experimental results show that short-term investors who view a COI disclosure are significantly less willing to invest in the recommended stock compared to short-term investors who do not view such a disclosure, while the presence of a COI disclosure does not significantly affect long-term investors’ willingness to invest. Results further demonstrate that the COI disclosure decreases short-term investors’ willingness to invest by reducing their perception of analysts’ trustworthiness and expertness. This study provides evidence on when and how the COI disclosure can influence investors’ behavior and enhances our understanding of investors’ reactions to cautionary disclaimers

Nano-electromechanical switchable photonic metamaterials

We introduce mechanically reconfigurable electrostatically-driven photonic metamaterials (RPMs) as a generic platform for large-range tuning and switching of photonic metamaterial properties. Here we illustrate this concept with a high-contrast metamaterial electro-optic switch exhibiting relative reflection changes of up to 72% in the optical part of the spectrum

Mathematical Modelling on RLCG Transmission Lines

A new model on RLCG transmissions lines is presented in the paper. The model suits to be taken to directly simulating a circuit system in timedomain. Mathematically, a circuit system with distributed elements may be described by a special kind of nonlinear integral-differential-algebraic equations with multiple constant delays