Structural transitions of ion strings in quantum potentials

We analyse the stability and dynamics of an ion chain confined inside a high-finesse optical resonator. When the dipolar transition of the ions strongly couples to one cavity mode, the mechanical effects of light modify the chain properties close to a structural transition. We focus on the linear chain close to the zigzag instability and show that linear and zigzag arrays are bistable for certain strengths of the laser pumping the cavity. For these regimes the chain is cooled into one of the configurations by cavity-enhanced photon scattering. The excitations of these structures mix photonic and vibrational fluctuations, which can be entangled at steady state. These features are signalled by Fano-like resonances in the spectrum of light at the cavity output.Comment: 5 pages, 3 figs - version to appear in PR

Taxation and Income Distribution Dynamics in a Neoclassical Growth Model

We examine how changes in tax policies affect the dynamics of the distributions of wealth and income in a Ramsey model in which agents differ in their initial capital endowment. The endogeneity of the labor supply plays a crucial role in determining inequality, as tax changes that affect hours of work will affect the distribution of wealth and income, reinforcing or offsetting the direct redistributive impact of taxes. Our results indicate that tax policies that reduce the labor supply are associated with lower output but also with a more equal distribution of after-tax income. We illustrate these effects by examining the impact of recent tax changes observed in the US and in European economies.taxation; wealth distribution; income distribution; endogenous labor supply; transitional dynamics