Anderson-type model for a molecule adsorbed on a metal surface

We investigate a modified Anderson model to study the local density of states (LDOS) of a molecular wire adsorbed on a metal. Using a self-consistent mean-field type approach we find an exponential decay of the LDOS along the molecule. A repulsive on-site interaction on the molecule suppresses the tunneling and decreases the characteristic decay length.Comment: 7 pages (using europhys.sty), 5 EPS figures, To appear in Europhys. Let

Coupling Circuit Resonators Among Themselves and To Nitrogen-Vacancy Centers in Diamond

We propose a scheme to couple NV centers in diamond through coplanar waveguide resonators. The central conductor of the resonator is split into several pieces which are coupled strongly with each other via simple capacitive junctions or superconducting Josephson junctions. The NV centers are then put at the junctions. The discontinuity at the junctions induces a large local magnetic field, with which the NV centers are strongly coupled to the circuit resonator. The coupling strength $g$ between the resonator and the NV center is of order of $g/2\pi\sim 1$--30\unit{MHz}.Comment: 4 pages; 3 figures; several typos corrected; figure 1 regenerate

Infantile mortality and fertility decisions in a stochastic environment

We analyze the effect of stochastic survival of children on fertility decision in a dynastic utility model where saving, so to speak, can only be made through having children, the number of which is an endogenous decision to the household. In our stochastic framework where the rate of population change undergoes a process of Brownian motion, the probability distribution of the steady state is well determined, and saving via the number of offsprings incorporates a precautionary component. Any health care assistance proposed to reduce the variance of the Brownian process, for example, to reduce the risk of premature infantile mortality, would have a negative effect on the fertility rate and a positive effect on the per capita consumption in the long run.Brownian motion