Ferreting out the Fluffy Bunnies: Entanglement constrained by Generalized superselection rules

Entanglement is a resource central to quantum information (QI). In particular, entanglement shared between two distant parties allows them to do certain tasks that would otherwise be impossible. In this context, we study the effect on the available entanglement of physical restrictions on the local operations that can be performed by the two parties. We enforce these physical restrictions by generalized superselection rules (SSRs), which we define to be associated with a given group of physical transformations. Specifically the generalized SSR is that the local operations must be covariant with respect to that group. Then we operationally define the entanglement constrained by a SSR, and show that it may be far below that expected on the basis of a naive (or ``fluffy bunny'') calculation. We consider two examples. The first is a particle number SSR. Using this we show that for a two-mode BEC (with Alice owning mode $A$ and Bob mode $B$), the useful entanglement shared by Alice and Bob is identically zero. The second, a SSR associated with the symmetric group, is applicable to ensemble QI processing such as in liquid-NMR. We prove that even for an ensemble comprising many pairs of qubits, with each pair described by a pure Bell state, the entanglement per pair constrained by this SSR goes to zero for a large ensemble.Comment: 8 pages, proceedings paper for an invited talk at 16th International Conference on Laser Spectroscopy (2003

The Therapeutic Bond Scales: Psychometric Characteristics and Relationship to Treatment Effectiveness

The Therapeutic Bond Scales assess the quality of the therapeutic relationship from the patient\u27s perspective. The therapeutic bond is composed of 3 aspects: working alliance, empathic resonance, and mutual affirmation. Scales were developed to measure these aspects and the therapeutic bond as a whole. The correlations between these scales and 2 measures of outcome (session quality assessed by the patient and termination outcome evaluated by nonparticipant raters) were examined. All scales were significantly correlated with session quality. Therapeutic bond was significantly correlated with termination outcome in both a linear and a curvilinear fashion, suggesting that, at least in the initial phase of therapy, the therapeutic bond can be too high as well as too low

Higgs-regularized three-loop four-gluon amplitude in N=4 SYM: exponentiation and Regge limits

We compute the three-loop contribution to the N=4 supersymmetric Yang-Mills planar four-gluon amplitude using the recently-proposed Higgs IR regulator of Alday, Henn, Plefka, and Schuster. In particular, we test the proposed exponential ansatz for the four-gluon amplitude that is the analog of the BDS ansatz in dimensional regularization. By evaluating our results at a number of kinematic points, and also in several kinematic limits, we establish the validity of this ansatz at the three-loop level. We also examine the Regge limit of the planar four-gluon amplitude using several different IR regulators: dimensional regularization, Higgs regularization, and a cutoff regularization. In the latter two schemes, it is shown that the leading logarithmic (LL) behavior of the amplitudes, and therefore the lowest-order approximation to the gluon Regge trajectory, can be correctly obtained from the ladder approximation of the sum of diagrams. In dimensional regularization, on the other hand, there is no single dominant set of diagrams in the LL approximation. We also compute the NLL and NNLL behavior of the L-loop ladder diagram using Higgs regularization.Comment: 45 pages, 9 figures; v3: major revision (more stringent tests, discussion of order of limits in the Regge regime

Good vs complementary genes for parasite resistance and the evolution of mate choice

BACKGROUND: Female mate choice may be adaptive when males exhibit heritable genetic variation at loci encoding resistance to infectious disease. The Hamilton-Zuk hypothesis predicts that females should assess the genetic quality of males by monitoring traits that indicate health and vigor (condition-dependent choice, or CD). Alternatively, some females may employ a more direct method of screening and select mates based on the dissimilarity of alleles at the major histocompatibility loci (we refer to this as opposites-attract, or OA). Empirical studies suggest that both forms of mate choice exist, but little is known about the potential for natural selection to shape the two strategies in nature. RESULTS: We used computer simulation models to examine the evolutionary fates of the two forms of mate choice in populations at risk for infection by debilitating parasites. We found that populations exhibiting random mating (no mate choice) can be invaded and replaced completely by individuals practicing CD type mate choice. We also found that an allele encoding OA choice can increase when rare in randomly mating populations, but that it does not go to fixation under selection. A similar result was obtained when the OA strategy was introduced into populations practicing CD mate choice. As before, we found that the OA choice allele will increase when rare, and that it will not go to fixation under selection. The converse however was not true, as CD individuals gain no rare advantage when introduced into an OA population. CONCLUSIONS: Taken together, the results suggest that, when rare, OA is the best strategy for parasite evasion (of those considered here). The consequence of OA increasing in the population, however, is to reduce the parasite driven genotype oscillations and facilitate the breakdown of linkage disequilibrium at the disease-resistance loci. This leads to a neutrally stable situation in which different strategies have equal fitness, and suggests that multiple forms of mate choice may be expected to occur in populations at risk from infectious disease

Characterization of a qubit Hamiltonian using adaptive measurements in a fixed basis

We investigate schemes for Hamiltonian parameter estimation of a two-level system using repeated measurements in a fixed basis. The simplest (Fourier based) schemes yield an estimate with a mean square error (MSE) that decreases at best as a power law ~N^{-2} in the number of measurements N. By contrast, we present numerical simulations indicating that an adaptive Bayesian algorithm, where the time between measurements can be adjusted based on prior measurement results, yields a MSE which appears to scale close to \exp(-0.3 N). That is, measurements in a single fixed basis are sufficient to achieve exponential scaling in N.Comment: 5 pages, 3 figures, 1 table. Published versio

An Evaluation of the Sensitivity of the Landsat Multispectral Scanner to Variations of Species, Crown Closure, Age, and Thinning within a Forest Plantation

Many scientists investigating forestry problems have advocated the use of operational satellite remote sensing systems as a source of forest inventory information. Satellite systems offer the potential of world-wide repeat coverage, but their inability to discriminate individual trees restricts the level of detailed forest information that can be acquired. Forested lands are easily identified on Landsat multispectral scanner (MSS) imagery, and the discrimination between mixed decidious and evergreen forest stands can be made with multi-date comparisons. This study concentrates on the question of how much more detailed information can be reliably obtained from Landsat MSS data. The purpose of this study is to evaluate the sensitivity of the Landsat MSS to: 1) variations of species within a forest plantation and 2) age, crown closure, and stand densities (i.e. thinnings) within the species. This investigation can be justified in several ways. First, as a geographical study; plant geography is the branch of science that attempts to describe and explain the uneven distribution of plants upon the surface of the earth. The distribution of plants reflects the influence of several factors such as climatic conditions, precipitation, topography, soils and human activity. Thus, vegetation serves to give a region its character, and may be used to differentiate regions and their components. The first step toward describing and explaining plant distributions is to map them. The Landsat remote sensing system provides geographers with a powerful tool for mapping and monitoring the earth\u27s vegetation. This study, to evaluate the sensitivity of the Landsat MSS to subtle variations of vegetation within a man-made forest, is an exercise in vegetation mapping. Another justification for this study is based upon the growing need of forest managers for more extensive and detailed forest data. This study is a continuation of previous investigations by others to determine the amount of detailed forest information available in Landsat data. This study will attempt to determine whether combinations of species, age, crown closure and thinnings within a forest plantation result in unique spectral signatures that can be detected by the Landsat MSS