Skyrmions in Quantum Hall Systems with Realistic Force-Laws

We study the charged excitations of quantum Hall systems at integer filling fractions $\nu=2n+1$, for a force-law that takes account of the finite width of the electron gas. For typical values of this width, in the limit of vanishing Zeeman energy we find that the low-energy excitations are ``skyrmions'' not only at $\nu=1$ but also at higher filling fractions. Our results lead to the prediction that, in typical samples, abrupt transitions to charged excitations with very large spins should be observable at filling fractions higher than $\nu=1$ if the Zeeman energy is reduced sufficiently.Comment: 5 pages, 3 ps-figures, revtex with epsf.tex and multicol.sty. To appear in Physical Review

Optical Flux Lattices for Ultracold Atomic Gases

We show that simple laser configurations can give rise to "optical flux lattices", in which optically dressed atoms experience a periodic effective magnetic flux with high mean density. These potentials lead to narrow energy bands with non-zero Chern number. Optical flux lattices will greatly facilitate the achievement of the quantum Hall regime for ultracold atomic gases

Is the U.S. Current Account Deficit Sustainable? Will It Be Sustained?

U.S. Current Account Deficit, Sustainable, Deficit, U.S. Current Account, macroeconomics

Living with Global Imbalances: A Contrarian View

Three propositions have become conventional wisdom in Washington and elsewhere: Americans save too little. The US current account deficit is thus unsustainably large. The Chinese currency must appreciate significantly to bring the global economy into sustainable balance. All these separate but related propositions are highly questionable, the author says. He suggests that Americans save quite enough for future generations, that the startlingly large US current account deficit is not only sustainable but a natural feature of today's highly globalized economy, and that a revaluation of the Chinese currency, far from alleviating global imbalances, would run the risk of precipitating a financial crisis.

Resource Needs Revisited

macroeconomics, resource needs

Dealing with the Trade Deficit in a Floating Rate System

macroeconomics, trade deficit, floating rate system