SOCIAL CHANGE IN AMERICAN UNIVERSITIES

Teaching/Communication/Extension/Profession,

When a quantum measurement can be implemented locally ... and when it cannot

Local operations on subsystems and classical communication between parties (LOCC) constitute the most general protocols available on spatially separated quantum systems. Every LOCC protocol implements a separable generalized measurement -- a complete measurement for which every outcome corresponds to a tensor product of operators on individual subsystems -- but it is known that there exist separable measurements that cannot be implemented by LOCC. A longstanding problem in quantum information theory is to understand the difference between LOCC and the full set of separable measurements. In this paper, we show how to construct an LOCC protocol to implement an arbitrary separable measurement, except that with those measurements for which no LOCC protocol exists, the method shows explicitly that this is the case.Comment: 21 pages, 7 figures. Extensively revised to include details of all arguments, explicitly proving all results in full rigor. Version 3 has sections reordered and other restructuring, but otherwise contains the same discussion as version

Method and apparatus for stable silicon dioxide layers on silicon grown in silicon nitride ambient

A method and apparatus for thermally growing stable silicon dioxide layers on silicon is disclosed. A previously etched and baked silicon nitride tube placed in a furnace is used to grow the silicon dioxide. First, pure oxygen is allowed to flow through the tube to initially coat the inside surface of the tube with a thin layer of silicon dioxide. After the tube is coated with the thin layer of silicon dioxide, the silicon is oxidized thermally in a normal fashion. If the tube becomes contaminated, the silicon dioxide is etched off thereby exposing clean silicon nitride and then the inside of the tube is recoated with silicon dioxide. As is disclosed, the silicon nitride tube can also be used as the ambient for the pyrolytic decomposition of silane and ammonia to form thin layers of clean silicon nitride

Chen ranks and resonance

The Chen groups of a group $G$ are the lower central series quotients of the maximal metabelian quotient of $G$. Under certain conditions, we relate the ranks of the Chen groups to the first resonance variety of $G$, a jump locus for the cohomology of $G$. In the case where $G$ is the fundamental group of the complement of a complex hyperplane arrangement, our results positively resolve Suciu's Chen ranks conjecture. We obtain explicit formulas for the Chen ranks of a number of groups of broad interest, including pure Artin groups associated to Coxeter groups, and the group of basis-conjugating automorphisms of a finitely generated free group.Comment: final version, to appear in Advances in Mathematic

Pressure suppression of electron correlation in the collapsed tetragonal phase of CaFe2As2: A DFT-DMFT investigation

Recent studies reveal a pressure induced transition from a paramagnetic tetragonal phase (T) to a collapsed tetragonal phase (CT) in CaFe2As2, which was found to be superconducting with pressure at low temperature. We have investigated the effects of electron correlation and a local fluctuating moment in both tetragonal and collapsed tetragonal phases of the paramagnetic CaFe2As2 using self-consistent DFT-DMFT with continuous time quantum Monte Carlo as the impurity solver. From the computed optical conductivity, we find a gain in the optical kinetic energy due to the loss in Hund's rule coupling energy in the CT phase. We find that the transition from T to CT turns CaFe2As2 from a bad metal into a good metal. Computed mass enhancement and local moments also show a significant decrease in the CT phase, which confirms the suppression of the electron correlation in the CT phase of CaFe2As2

Phase Transitions in the NMSSM

We study phase transitions in the Next-to-Minimal Supersymmetric Standard Model (NMSSM) with the weak scale vacuum expectation values of the singlet scalar, constrained by Higgs spectrum and vacuum stability. We find four different types of phase transitions, three of which have two-stage nature. In particular, one of the two-stage transitions admits strongly first order electroweak phase transition, even with heavy squarks. We introduce a tree-level explicit CP violation in the Higgs sector, which does not affect the neutron electric dipole moment. In contrast to the MSSM with the CP violation in the squark sector, a strongly first order phase transition is not so weakened by this CP violation.Comment: 21 pages, 8 figure

Asymptotically Unambitious Artificial General Intelligence

General intelligence, the ability to solve arbitrary solvable problems, is supposed by many to be artificially constructible. Narrow intelligence, the ability to solve a given particularly difficult problem, has seen impressive recent development. Notable examples include self-driving cars, Go engines, image classifiers, and translators. Artificial General Intelligence (AGI) presents dangers that narrow intelligence does not: if something smarter than us across every domain were indifferent to our concerns, it would be an existential threat to humanity, just as we threaten many species despite no ill will. Even the theory of how to maintain the alignment of an AGI's goals with our own has proven highly elusive. We present the first algorithm we are aware of for asymptotically unambitious AGI, where "unambitiousness" includes not seeking arbitrary power. Thus, we identify an exception to the Instrumental Convergence Thesis, which is roughly that by default, an AGI would seek power, including over us.Comment: 9 pages with 5 figures; 10 page Appendix with 2 figure