R. G. Herb Condensed Matter Seminars |
Events During the Week of April 7th through April 14th, 2013
Monday, April 8th, 2013
- Fluctuation effects in disordered superconducting films above Tc
- Time: 4:30 pm
- Place: 5310 Chamberlin
- Speaker: Alexander Finkelstein, Weizmann Institute of Science
- Abstract: I will report on the fluctuation corrections in homogeneously disordered superconducting films.
I will start with the Nernst and Hall Effects where fluctuation corrections can be tracked experimentally to temperatures more than order of magnitude above Tc and magnetic fields well above the upper critical field, Hc2(0). There is a quantitative agreement between our theoretical analysis and recent data obtained in conventional superconductors for the Nernst Effect (K. Behnia, France) and the Hall conductivity (Kapitulnik, Stanford) and for the Nernst Effect in certain high-Tc-family materials (L.Taillefer, Canada).
I will also report about our recent calculation of the fluctuation corrections, which is based on the Usadel equation in the real-time formulation. We adjust this approach to derive analytic expressions for the corrections to the longitudinal conductivity in the entire metallic part of the temperature-magnetic field phase diagram. This method allows us to obtain fluctuation corrections in a compact and effective way, establishing a direct connection between phenomenological and microscopic calculations. - Host: Chubukov
Tuesday, April 9th, 2013
- No events scheduled
Wednesday, April 10th, 2013
- No events scheduled
Thursday, April 11th, 2013
- The Objective Indefiniteness Interpretation of Quantum Mechanics: Partition logic, logical information theory, and quantum mechanics
- Time: 11:00 am
- Place: 5310 Chamberlin
- Speaker: David Ellerman, University of California, Riverside
- Abstract: Quantum mechanics (QM) is not compatible with the usual Boolean logic of subsets where elements have definite properties "all the way down." But there is a recently developed dual logic of partitions (subsets and partitions are category-theoretically dual) which models indefinite elements that become more definite as distinctions are made. If quantum mechanics was also incompatible with this unique dual logic of partitions, then one might "press the panic button" and postulate unknowable hidden variables to restore definiteness or soar off into the void with "many worlds" or the like.
But quantum mechanics fits perfectly with the dual logic of partitions. There is no need for (more) bizarre flights of fancy to "interpret" QM. This objective indefiniteness approach to QM does not restore our common sense assumption of definiteness down into the quantum realm. But it does restore sanity and understanding to the whole framework. That is, we now have the logic that precisely fits QM--a logic that was developed independently (i.e., without any thought of a QM connection) and that is the unique mathematical dual to ordinary Boolean subset logic, the logic assumed in classical physics. Moreover the normalized counting measure on partitions gives the quantum-relevant logical information theory--just as Boole developed logical probabilities as the normalized counting measure on subsets. Indeed, when the mathematics of partition logic and logical information theory is linearized and lifted to complex vector spaces, then it yields the mathematical framework of quantum mechanics (but not the specifically physical postulates).
The key concepts explicated by this approach are the old ideas of "objective indefiniteness" (emphasized by Abner Shimony), objective probabilities, and the objective realization of information, "its" from "dits" (= distinctions). Since partition logic, logical information theory, and the lifting program "derives" the mathematics of quantum mechanics, it shows how that QM framework can be interpreted--and this set of results gives what might be called the objective indefiniteness interpretation of quantum mechanics. - Host: Huber
Friday, April 12th, 2013
- No events scheduled