A high-flux source of polarization-entangled photons from a periodically-poled KTP parametric downconverter

We have demonstrated a high-flux source of polarization-entangled photons using a type-II phase-matched periodically-poled KTP parametric downconverter in a collinearly propagating configuration. We have observed quantum interference between the single-beam downconverted photons with a visibility of 99% and a measured coincidence flux of 300/s/mW of pump. The Clauser-Horne-Shimony-Holt version of Bell's inequality was violated with a value of 2.711 +/- 0.017.Comment: 7 pages submitted to Physical Review

Transient thermal characterization of suspended monolayer MoS2_2

We measure the thermal time constants of suspended single layer molybdenum disulfide drums by their thermomechanical response to a high-frequency modulated laser. From this measurement the thermal diffusivity of single layer MoS$_2$ is found to be 1.14 $\times$ 10$^{-5}$ m$^2$/s on average. Using a model for the thermal time constants and a model assuming continuum heat transport, we extract thermal conductivities at room temperature between 10 to 40 W/(m$\cdot$K). Significant device-to-device variation in the thermal diffusivity is observed. Based on statistical analysis we conclude that these variations in thermal diffusivity are caused by microscopic defects that have a large impact on phonon scattering, but do not affect the resonance frequency and damping of the membrane's lowest eigenmode. By combining the experimental thermal diffusivity with literature values of the thermal conductivity, a method is presented to determine the specific heat of suspended 2D materials, which is estimated to be 255 $\pm$ 104 J/(kg$\cdot$K) for single layer MoS$_2$

Direct measurement of optical quasidistribution functions: multimode theory and homodyne tests of Bell's inequalities

We develop a multimode theory of direct homodyne measurements of quantum optical quasidistribution functions. We demonstrate that unbalanced homodyning with appropriately shaped auxiliary coherent fields allows one to sample point-by-point different phase space representations of the electromagnetic field. Our analysis includes practical factors that are likely to affect the outcome of a realistic experiment, such as non-unit detection efficiency, imperfect mode matching, and dark counts. We apply the developed theory to discuss feasibility of observing a loophole-free violation of Bell's inequalities by measuring joint two-mode quasidistribution functions under locality conditions by photon counting. We determine the range of parameters of the experimental setup that enable violation of Bell's inequalities for two states exhibiting entanglement in the Fock basis: a one-photon Fock state divided by a 50:50 beam splitter, and a two-mode squeezed vacuum state produced in the process of non-degenerate parametric down-conversion.Comment: 18 pages, 7 figure

Enhancing declarative debugging with loop expansion and tree compression

This work has been partially supported by the Spanish Ministerio de Econom´ıa y Competitividad (Secretar´ıa de Estado de Investigaci´on, Desarrollo e Innovaci´on) under grant TIN2008-06622-C03-02 and by the Generalitat Valenciana under grant PROMETEO/2011/052. David Insa was partially supported by the Spanish Ministerio de Eduaci´on under FPU grant AP2010-4415Insa Cabrera, D.; Silva Galiana, JF.; Tomás Franco, C. (2013). Enhancing declarative debugging with loop expansion and tree compression. En Logic-Based Program Synthesis and Transformation. Springer Verlag (Germany). 71-88. https://doi.org/10.1007/978-3-642-38197-3_6S7188Binks, D.: Declarative Debugging in Gödel. PhD thesis, University of Bristol (1995)Calejo, M.: A Framework for Declarative Prolog Debugging. PhD thesis, New University of Lisbon (1992)Davie, T., Chitil, O.: Hat-delta: One Right Does Make a Wrong. In: Butterfield, A. (ed.) Draft Proceedings of the 17th International Workshop on Implementation and Application of Functional Languages, IFL 2005, p. 11. Tech. Report No: TCD-CS-2005-60, University of Dublin, Ireland (September 2005)Davie, T., Chitil, O.: Hat-delta: One Right Does Make a Wrong. In: Seventh Symposium on Trends in Functional Programming, TFP 2006 (April 2006)Harrison, P.G., Khoshnevisan, H.: A new approach to recursion removal. Theor. Comput. Sci. 93(1), 91–113 (1992)Hirunkitti, V., Hogger, C.J.: A Generalised Query Minimisation for Program Debugging. In: Adsul, B. (ed.) AADEBUG 1993. LNCS, vol. 749, pp. 153–170. Springer, Heidelberg (1993)Insa, D., Silva, J.: An Algorithmic Debugger for Java. In: Proc. of the 26th IEEE International Conference on Software Maintenance, pp. 1–6 (2010)Insa, D., Silva, J.: Debugging with Incomplete and Dynamically Generated Execution Trees. In: Proc. of the 20th International Symposium on Logic-based Program Synthesis and Transformation, LOPSTR 2010, Austria (2010)Insa, D., Silva, J.: A Transformation of Iterative Loops into Recursive Loops. Technical Report DSIC/05/12, Universidad Politécnica de Valencia (2012), http://www.dsic.upv.es/~jsilva/research.htm#techsInsa, D., Silva, J., Tomás, C.: Enhancing Declarative Debugging with Loop Expansion and Tree Compression. Technical Report DSIC/11/12, Universidad Politécnica de Valencia (2012), http://www.dsic.upv.es/~jsilva/research.htm#techsLiu, Y.A., Stoller, S.D.: From recursion to iteration: what are the optimizations? In: Proceedings of the 2000 ACM SIGPLAN Workshop on Partial Evaluation and Semantics-Based Program Manipulation, PEPM 2000, pp. 73–82. ACM, New York (2000)Lloyd, J.W.: Declarative error diagnosis. New Gen. Comput. 5(2), 133–154 (1987)Nilsson, H.: Declarative Debugging for Lazy Functional Languages. PhD thesis, Linköping, Sweden (May 1998)NIST: The Economic Impacts of Inadequate Infrastructure for Software Testing. USA National Institute of Standards and Technology, NIST Planning Report 02-3 (May 2002)Riesco, A., Verdejo, A., Martí-Oliet, N., Caballero, R.: Declarative Debugging of Rewriting Logic Specifications. Journal of Logic and Algebraic Programming (September 2011)Shapiro, E.Y.: Algorithmic Program Debugging. MIT Press (1982)Silva, J.: A Survey on Algorithmic Debugging Strategies. Advances in Engineering Software 42(11), 976–991 (2011)Yi, Q., Adve, V., Kennedy, K.: Transforming loops to recursion for multi-level memory hierarchies. In: Proceedings of the SIGPLAN 2000 Conference on Programming Language Design and Implementation, pp. 169–181 (2000

Measurement of the space-time interval between two events using the retarded and advanced times of each event with respect to a time-like world-line

Several recent studies have been devoted to investigating the limitations that ordinary quantum mechanics and/or quantum gravity might impose on the measurability of space-time observables. These analyses are often confined to the simplified context of two-dimensional flat space-time and rely on a simple procedure for the measurement of space-like distances based on the exchange of light signals. We present a generalization of this measurement procedure applicable to all three types of space-time intervals between two events in space-times of any number of dimensions. We also present some preliminary observations on an alternative measurement procedure that can be applied taking into account the gravitational field of the measuring apparatus, and briefly discuss quantum limitations of measurability in this context.Comment: 17 page

Polarization quantum properties in type-II Optical Parametric Oscillator below threshold

We study the far field spatial distribution of the quantum fluctuations in the transverse profile of the output light beam generated by a type II Optical Parametric Oscillator below threshold, including the effects of transverse walk-off. We study how quadrature field correlations depend on the polarization. We find spatial EPR entanglement in quadrature-polarization components: For the far field points not affected by walk-off there is almost complete noise suppression in the proper quadratures difference of any orthogonal polarization components. We show the entanglement of the state of symmetric intense, or macroscopic, spatial light modes. We also investigate nonclassical polarization properties in terms of the Stokes operators. We find perfect correlations in all Stokes parameters measured in opposite far field points in the direction orthogonal to the walk-off, while locally the field is unpolarized and we find no polarization squeezing.Comment: 16 pages, 18 figure

Grover search with pairs of trapped ions

The desired interference required for quantum computing may be modified by the wave function oscillations for the implementation of quantum algorithms[Phys.Rev.Lett.84(2000)1615]. To diminish such detrimental effect, we propose a scheme with trapped ion-pairs being qubits and apply the scheme to the Grover search. It can be found that our scheme can not only carry out a full Grover search, but also meet the requirement for the scalable hot-ion quantum computing. Moreover, the ion-pair qubits in our scheme are more robust against the decoherence and the dissipation caused by the environment than single-particle qubits proposed before.Comment: RevTe

Slater-Pauling Behavior of the Half-Ferromagnetic Full-Heusler Alloys

Using the full-potential screened Korringa-Kohn-Rostoker method we study the full-Heusler alloys based on Co, Fe, Rh and Ru. We show that many of these compounds show a half-metallic behavior, however in contrast to the half-Heusler alloys the energy gap in the minority band is extremely small. These full-Heusler compounds show a Slater-Pauling behavior and the total spin-magnetic moment per unit cell (M_t) scales with the total number of valence electrons (Z_t) following the rule: M_t=Z_t-24. We explain why the spin-down band contains exactly 12 electrons using arguments based on the group theory and show that this rule holds also for compounds with less than 24 valence electrons. Finally we discuss the deviations from this rule and the differences compared to the half-Heusler alloys.Comment: 10 pages, 8 figures, revised figure 3, new text adde

The Influence of Shc Proteins on Life Span in Mice

The signaling molecule p66Shc is often described as a longevity protein. This conclusion is based on a single life span study that used a small number of mice. The purpose of the present studies was to measure life span in a sufficient number of mice to determine if longevity is altered in mice with decreased Shc levels (ShcKO). Studies were completed at UC Davis and the European Institute of Oncology (EIO). At UC Davis, male C57BL/6J WT and ShcKO mice were fed 5% or 40% calorie-restricted (CR) diets. In the 5% CR group, there was no difference in survival curves between genotypes. There was also no difference between genotypes in prevalence of neoplasms or other measures of end-of-life pathology. At 40% calorie restriction group, 70th percentile survival was increased in ShcKO, while there were no differences between genotypes in median or subsequent life span measures. At EIO, there was no increase in life span in ShcKO male or female mice on C57BL/6J , 129Sv, or hybrid C57BL/6J -129Sv backgrounds. These studies indicate that p66Shc is not a longevity protein. However, additional studies are needed to determine the extent to which Shc proteins may influence the onset and severity of specific age-related diseases

A measurement of the tau mass and the first CPT test with tau leptons

We measure the mass of the tau lepton to be 1775.1+-1.6(stat)+-1.0(syst.) MeV using tau pairs from Z0 decays. To test CPT invariance we compare the masses of the positively and negatively charged tau leptons. The relative mass difference is found to be smaller than 3.0 10^-3 at the 90% confidence level.Comment: 10 pages, 4 figures, Submitted to Phys. Letts.