Exact Relations for a Strongly-interacting Fermi Gas from the Operator Product Expansion

The momentum distribution in a Fermi gas with two spin states and a large scattering length has a tail that falls off like 1/k^4 at large momentum k, as pointed out by Shina Tan. He used novel methods to derive exact relations between the coefficient of the tail in the momentum distribution and various other properties of the system. We present simple derivations of these relations using the operator product expansion for quantum fields. We identify the coefficient as the integral over space of the expectation value of a local operator that measures the density of pairs.Comment: 4 pages, 2 figure

Exact Relations for a Strongly-interacting Fermi Gas near a Feshbach Resonance

A set of universal relations between various properties of any few-body or many-body system consisting of fermions with two spin states and a large but finite scattering length have been derived by Shina Tan. We derive generalizations of the Tan relations for a two-channel model for fermions near a Feshbach resonance that includes a molecular state whose detuning energy controls the scattering length. We use quantum field theory methods, including renormalization and the operator product expansion, to derive these relations. They reduce to the Tan relations as the scattering length is made increasingly large.Comment: 25 pages, 8 figure

Oregon Psychologists on Prescriptive Authority: Divided Views and Little Knowledge

With over half of all states having considered legislating prescriptive authority, an immense amount of time and money has been invested. The literature is limited in terms of understanding if opinions toward prescriptive authority are grounded in knowledge and what implications that has for altering these opinions. Following a veto of a prescriptive authority bill in Oregon, 399 licensed Oregon clinical psychologists were surveyed regarding their attitudes and knowledge. In terms of knowledge, only 6.5% knew which three states/territories currently have prescriptive authority and 70.4% were unfamiliar with any of the prerequisites for postdoctoral training in psychopharmacology. Reflecting division, 43.4% were in favor, 25.4% were undecided, and 31.2% were in opposition to broadening privileges for psychologists. Further, only 15.2% expressed interest in pursuing training or 6.7% in becoming prescribers. Data on access, training, and legislative costs were presented to participants in the education condition. These participants showed significant gains in their knowledge across all domains and their opinions shifted only in these specific areas leaving their general stance on the issue unchanged. In contrast to ardent supporters who argue that their “data should provide reassurance to psychologists spearheading legislative initiatives” because of high approval ratings (Sammons et al., 2000, p. 608), our data suggest disagreement amongst a group of professionals who are not particularly well-informed, nor interested in becoming prescribers. Future work should investigate whether expanding the data relevant to other facets of the argument contributes to further targeted change or an overall change in opinion toward prescriptive authority

High-rate, high-fidelity entanglement of qubits across an elementary quantum network

We demonstrate remote entanglement of trapped-ion qubits via a quantum-optical fiber link with fidelity and rate approaching those of local operations. Two ${}^{88}$Sr${}^{+}$ qubits are entangled via the polarization degree of freedom of two photons which are coupled by high-numerical-aperture lenses into single-mode optical fibers and interfere on a beamsplitter. A novel geometry allows high-efficiency photon collection while maintaining unit fidelity for ion-photon entanglement. We generate remote Bell pairs with fidelity $F=0.940(5)$ at an average rate $182\,\mathrm{s}^{-1}$ (success probability $2.18\times10^{-4}$).Comment: v2 updated to include responses to reviewers, as published in PR

Evaluation of the ALMA Prototype Antennas

The ALMA North American and European prototype antennas have been evaluated by a variety of measurement systems to quantify the major performance specifications. Nearfield holography was used to set the reflector surfaces to 17 microns RMS. Pointing and fast switching performance was determined with an optical telescope and by millimeter wavelength radiometry, yielding 2 arcsec absolute and 0.6 arcsec offset pointing accuracies. Path length stability was measured to be less than or approximately equal to 20 microns over 10 minute time periods using optical measurement devices. Dynamical performance was studied with a set of accelerometers, providing data on wind induced tracking errors and structural deformation. Considering all measurements made during this evaluation, both prototype antennas meet the major ALMA antenna performance specifications.Comment: 83 pages, 36 figures, AASTex format, to appear in PASP September 2006 issu