Coupled-channel pseudo-potential description of the Feshbach resonance in two dimensions

We derive pseudo-potentials that describe the scattering between two particles in two spatial dimensions for any partial wave m, whose scattering strength is parameterized in terms of the m-dependent phase shift. Using our m=0 pseudo-potential, we develop a coupled channel model with 2D zero-range interactions, which describes the two-body physics across a Feshbach resonance. Our model predicts the scattering length, the binding energy and the "closed channel molecular fraction" of two particles; these observables can be measured in experiments on ultracold quasi-2D atomic Bose and Fermi gases with present-day technology.Comment: 4 pages, 3 figure

Learning Strategic Sophistication

We experimentally investigate coordination games in which cognition plays an important role, i.e. where outcomes are affected by the agents level of understanding of the game and the beliefs they form about each others understanding.We ask whether and when repeated exposure permits agents to learn to improve cognition in a strategic setting.We find evidence for strategic sophistication being learned, generalized and promoted.Agents acquire strategic sophistication in simple settings.They may fail to do so in similar but more demanding settings.Given the opportunity, they transfer learning from the simple to the more demanding task.There is heterogeneity in sophistication.We find some evidence for sophisticated agents trying to spread sophistication early in the game, provided there is a long enough time horizon.noncooperative games;laboratory group behavior

Climbing Mount Scalable: Physical-Resource Requirements for a Scalable Quantum Computer

The primary resource for quantum computation is Hilbert-space dimension. Whereas Hilbert space itself is an abstract construction, the number of dimensions available to a system is a physical quantity that requires physical resources. Avoiding a demand for an exponential amount of these resources places a fundamental constraint on the systems that are suitable for scalable quantum computation. To be scalable, the effective number of degrees of freedom in the computer must grow nearly linearly with the number of qubits in an equivalent qubit-based quantum computer.Comment: LATEX, 24 pages, 1 color .eps figure. This new version has been accepted for publication in Foundations of Physic