Quantum key distribution using a triggered quantum dot source emitting near 1.3 microns

We report the distribution of a cryptographic key, secure from photon number splitting attacks, over 35 km of optical fiber using single photons from an InAs quantum dot emitting ~1.3 microns in a pillar microcavity. Using below GaAs-bandgap optical excitation, we demonstrate suppression of multiphoton emission to 10% of the Poissonian level without detector dark count subtraction. The source is incorporated into a phase encoded interferometric scheme implementing the BB84 protocol for key distribution over standard telecommunication optical fiber. We show a transmission distance advantage over that possible with (length-optimized) uniform intensity weak coherent pulses at 1310 nm in the same system.Comment: 4 pages, 4 figure

Noncommutative Inspired Black Holes in Extra Dimensions

In a recent string theory motivated paper, Nicolini, Smailagic and Spallucci (NSS) presented an interesting model for a noncommutative inspired, Schwarzschild-like black hole solution in 4-dimensions. The essential effect of having noncommutative co-ordinates in this approach is to smear out matter distributions on a scale associated with the turn-on of noncommutativity which was taken to be near the 4-d Planck mass. In particular, NSS took this smearing to be essentially Gaussian. This energy scale is sufficiently large that in 4-d such effects may remain invisible indefinitely. Extra dimensional models which attempt to address the gauge hierarchy problem, however, allow for the possibility that the effective fundamental scale may not be far from $\sim$ 1 TeV, an energy regime that will soon be probed by experiments at both the LHC and ILC. In this paper we generalize the NSS model to the case where flat, toroidally compactified extra dimensions are accessible at the Terascale and examine the resulting modifications in black hole properties due to the existence of noncommutativity. We show that while many of the noncommutativity-induced black hole features found in 4-d by NSS persist, in some cases there can be significant modifications due the presence of extra dimensions. We also demonstrate that the essential features of this approach are not particularly sensitive to the Gaussian nature of the smearing employed by NSS.Comment: 30 pages, 12 figures; slight text modifications and references adde

TeV-Scale Black Hole Lifetimes in Extra-Dimensional Lovelock Gravity

We examine the mass loss rates and lifetimes of TeV-scale extra dimensional black holes (BH) in ADD-like models with Lovelock higher-curvature terms present in the action. In particular we focus on the predicted differences between the canonical and microcanonical ensemble statistical mechanics descriptions of the Hawking radiation that results in the decay of these BH. In even numbers of extra dimensions the employment of the microcanonical approach is shown to generally lead to a significant increase in the BH lifetime as in case of the Einstein-Hilbert action. For odd numbers of extra dimensions, stable BH remnants occur when employing either description provided the highest order allowed Lovelock invariant is present. However, in this case, the time dependence of the mass loss rates obtained employing the two approaches will be different. These effects are in principle measurable at future colliders.Comment: 27 pages, 9 figs; Refs. and discussion adde

Montana v. Wyoming: Sprinklers, Irrigation Water Use Efficiency and the Doctrine of Recapture

In 2007, Montana filed an original action with the United States Supreme Court asserting that certain water uses in Wyoming violated the Yellowstone River Compact (“Compact”). The litigation was triggered by severe drought in the basin between 2000 and 2006, during which period there was inadequate water available for Montana appropriators in the Tongue River and Powder River sub-basins. Montana raised four primary issues: irrigation of new acreage in Wyoming; new and expanded storage facilities; new groundwater pumping, especially associated with coalbed methane development; and increased consumption of water due to improved irrigation efficiency on existing irrigated acreage. In 2011, the U.S. Supreme Court decided the first substantive issue in this litigation: “Is a switch to more efficient irrigation with less return flow within the extent of Wyoming’s pre-1950 users’ existing appropriative rights, or is it an improper enlargement of that right to the detriment of Montana’s pre-1950 water users?” The Court held that such improvements are permitted under the Compact. This Article takes a careful look at this decision. It begins with an introduction to the physical setting, focusing on the Tongue and Powder sub-basins within the Yellowstone basin. It discusses Montana’s arguments why the Compact precludes improved irrigation efficiency that increases consumption and the Special Master’s rejection of those arguments. Next, the Article looks at the U.S. Supreme Court’s opinion. Finally, it offers some observations triggered by this litigation, critiques the doctrine of recapture in western water law, and supports the Court’s embrace of water use efficiency over protection of the status quo. We begin with a look at the Yellowstone River basin

Writing in Britain and Ireland, c. 400 to c. 800

No abstract available

Bis[4-(dimethyl­amino)pyridinium] tetra­bromidobis(4-methyl­phen­yl)stannate(IV)

In the title compound, (C7H11N2)2[SnBr4(C7H7)2], the tetra­bromidobis(4-methyl­phen­yl)stannate(IV) anion possesses a centre of inversion located at the SnIV atom. In the crystal structure, two inversion-related cations are linked to the anion via weak N—H⋯Br hydrogen bonds

Bis[4-(dimethyl­amino)pyridinium] tetra­bromidobis(4-chloro­phen­yl)stannate(IV)–4-bromo­chloro­benzene (1/1)

In the title compound, (C7H11N2)2[SnBr4(C6H4Cl)2]·C6H4BrCl, the SnIV atom in the tetra­bromidobis(4-chloro­phen­yl)stannate(IV) anion lies on a centre of inversion. The distances between the 4-(dimethyl­amino)pyridinium N atom and the Br atoms of the anion are 3.450 (2) and 3.452 (2) Å, suggesting weak hydrogen bonding. The 4-bromo­chloro­benzene solvent mol­ecule, which is a bromination by-product from the reaction, is disordered about a twofold rotation axis with approximately equal occupancy

Exoplanetary Geophysics -- An Emerging Discipline

Thousands of extrasolar planets have been discovered, and it is clear that the galactic planetary census draws on a diversity greatly exceeding that exhibited by the solar system's planets. We review significant landmarks in the chronology of extrasolar planet detection, and we give an overview of the varied observational techniques that are brought to bear. We then discuss the properties of the currently known distribution, using the mass-period diagram as a guide to delineating hot Jupiters, eccentric giant planets, and a third, highly populous, category that we term "ungiants", planets having masses less than 30 Earth masses and orbital periods less than 100 days. We then move to a discussion of the bulk compositions of the extrasolar planets. We discuss the long-standing problem of radius anomalies among giant planets, as well as issues posed by the unexpectedly large range in sizes observed for planets with masses somewhat greater than Earth's. We discuss the use of transit observations to probe the atmospheres of extrasolar planets; various measurements taken during primary transit, secondary eclipse, and through the full orbital period, can give clues to the atmospheric compositions, structures, and meteorologies. The extrasolar planet catalog, along with the details of our solar system and observations of star-forming regions and protoplanetary disks, provide a backdrop for a discussion of planet formation in which we review the elements of the favored pictures for how the terrestrial and giant planets were assembled. We conclude by listing several research questions that are relevant to the next ten years and beyond.Comment: Review chapter to appear in Treatise on Geophysics, 2nd Editio