Casimir-Polder Potential of a Driven Atom

We investigate theoretically the Casimir-Polder potential of an atom which is driven by a laser field close to a surface. This problem is addressed in the framework of macroscopic quantum electrodynamics using the Green's tensor formalism and we distinguish between two different approaches, a perturbative ansatz and a method based on Bloch equations. We apply our results to a concrete example, namely an atom close to a perfectly conducting mirror, and create a scenario where the tunable Casimir-Polder potential becomes similar to the respective potential of an undriven atom due to fluctuating field modes. Whereas the perturbative approach is restricted to large detunings, the ansatz based on Bloch equations is exact and yields an expression for the potential which does not exceed 1/2 of the undriven Casimir-Polder potential.Comment: 13 pages, 8 figure

Glass Ceilings and Open Doors: Women\u27s Advancement in the Legal Profession

This is a study exploring women\u27s integration into large corporate law practices and their mobility within firms

Non-additivity of optical and Casimir-Polder potentials

An atom irradiated by an off-resonant laser field near a surface is expected to experience the sum of two fundamental potentials, the optical potential of the laser field and the Casimir--Polder potential of the surface. Here, we report a new non-additive potential, namely the laser-induced Casimir--Polder potential, which arises from a correlated coupling of the atom with both the laser and the quantum vacuum. We apply this result to an experimentally realizable scenario of an atomic mirror with an evanescent laser beam leaking out of a surface. We show that the non-additive term is significant for realistic experimental parameters, transforming potential barriers into potential wells, which can be used to trap atoms near surfaces.Comment: 5 pages, 3 figure

Factors affecting lightning behavior in various regions of the United States

2014 Spring.Includes bibliographical references.Lightning activity varies greatly on a global scale. Global maps of total flash density show a strong tendency for lightning to favor continental areas over the open ocean, even in regions with similar instability. Previous studies have attributed the difference to thermodynamic and aerosol differences over continental regions, but the exact cause is still elusive. While this is not a global study, we attempt to characterize lightning activity in 4 different regions of the United States with high resolution Lightning Mapping Array (LMA) networks over one warm season. The regions of study are Washington, D.C. (DC), northern Alabama, central Oklahoma and northeast Colorado. A wide spectrum of environmental characteristics is afforded by these regions. Lightning characteristics include storm total flash rates, positive cloud-to-ground (+CG) strikes and intra-cloud (IC) to CG ratio (IC:CG). This is accomplished by using the CSU Lightning, Environmental, Aerosol and Radar (CLEAR) framework, first developed by Lang and Rutledge (2011), to objectively analyze large amounts of storm data. Lightning activity is provided by a new flash clustering algorithm, which produces total flash rates and IC flash rates when combined with NLDN CG data. The results have shown that lightning behavior has high variability throughout the regions of study. Median total storm flash rates range from approximately 1 flash/min in Alabama and DC to near 8 flashes/min in Colorado. Positive CG flash fractions exhibit a similar relationship with 10% of all CG flashes being positive polarity in Alabama and DC up to 40% in Colorado. The anomalous nature of the Colorado region is evident in all lightning metrics. Colorado is also characterized by an anomalous environment with high cloud base storms and coincident shallow warm cloud depths. Examination of all storms simultaneously has shown that relationships exist between total flash rate and environmental parameters. The similarity of these results to other studies on global scales is striking and provides evidence for the robustness of these relationships. Examination of relationships between radar and lightning intensity metrics are also performed. Similar behaviors between these intensity metrics are observed in all regions