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Univ Arizona, Dept Phys (198)

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Analysis of Polarizability Measurements Made with Atom Interferometry

Gregoire, Maxwell; Brooks, Nathan; Trubko, Raisa; Cronin, Alexander (MDPI AG, 2016-07-06)

We present revised measurements of the static electric dipole polarizabilities of K, Rb, and Cs based on atom interferometer experiments presented in [Phys. Rev. A 2015, 92, 052513] but now re-analyzed with new calibrations for the magnitude and geometry of the applied electric field gradient. The resulting polarizability values did not change, but the uncertainties were significantly reduced. Then, we interpret several measurements of alkali metal atomic polarizabilities in terms of atomic oscillator strengths f(ik), Einstein coefficients A(ik), state lifetimes tau(k), transition dipole matrix elements D-ik, line strengths S-ik, and van der Waals C-6 coefficients. Finally, we combine atom interferometer measurements of polarizabilities with independent measurements of lifetimes and C-6 values in order to quantify the residual contribution to polarizability due to all atomic transitions other than the principal ns-np(J) transitions for alkali metal atoms.

Effect of Mo insertion layers on the magnetoresistance and perpendicular magnetic anisotropy in Ta/CoFeB/MgO junctions

Almasi, H.; Xu, M.; Xu, Y.; Newhouse-Illige, T.; Wang, W. G. (AMER INST PHYSICS, 2016-07-18)

The effect of a thin Mo dusting layer inserted at the interface of Ta/CoFeB of perpendicular magnetic tunneling junction with MgO barriers was investigated. Unlike thick Mo layers that exhibited a strong (110) crystalline texture, the inserted Mo layer between Ta/CoFeB had little negative influence on the crystallization of CoFe (001), therefore combining the advantages of Mo as a good thermal barrier and Ta as a good boron sink. For optimized Mo dusting thickness, a large tunneling magnetoresistance of 208% was achieved in perpendicular magnetic tunneling junctions with superior thermal stability at 500 degrees C. Published by AIP Publishing.

Transient instability of rapidly rotating black holes

Gralla, Samuel E.; Zimmerman, Aaron; Zimmerman, Peter (AMER PHYSICAL SOC, 2016-10-13)

We analytically study the linear response of a near-extremal Kerr black hole to external scalar, electromagnetic, and gravitational field perturbations. We show that the energy density, electromagnetic field strength, and tidal force experienced by infalling observers exhibit transient growth near the horizon. The growth lasts arbitrarily long in the extremal limit, reproducing the horizon instability of extremal Kerr. We explain these results in terms of near-horizon geometry and discuss potential astrophysical implications.

Renormalizability of the nuclear many-body problem with the Skyrme interaction beyond mean field

Yang, C. J.; Grasso, M.; Moghrabi, K.; van Kolck, U. (AMER PHYSICAL SOC, 2017-05-26)

Phenomenological effective interactions like Skyrme forces are currently used in mean-field calculations in nuclear physics. Mean-field models have strong analogies with the first order of the perturbative many-body problem and the currently used effective interactions are adjusted at the mean-field level. In this work, we analyze the renormalizability of the nuclear many-body problem in the case where the effective Skyrme interaction is employed in its standard form and the perturbative problem is solved up to second order. We focus on symmetric nuclear matter and its equation of state, which can be calculated analytically at this order. It is shown that only by applying specific density dependence and constraints to the interaction parameters can renormalizability be guaranteed in principle. This indicates that the standard Skyrme interaction does not in general lead to a renormalizable theory. To achieve renormalizability, other terms should be added to the interaction and employed perturbatively only at first order.

Up, down, and strange nucleon axial form factors from lattice QCD

Green, Jeremy; Hasan, Nesreen; Meinel, Stefan; Engelhardt, Michael; Krieg, Stefan; Laeuchli, Jesse; Negele, John; Orginos, Kostas; Pochinsky, Andrew; Syritsyn, Sergey (AMER PHYSICAL SOC, 2017-06-14)

We report a calculation of the nucleon axial form factors G(A)(q)(Q(2)) and G(A)(q)(Q(2)) for all three light quark flavors q is an element of{u, d, s} in the range 0 <= Q(2) less than or similar to 1.2 GeV2 using lattice QCD. This work was done using a single ensemble with pion mass 317 MeVand made use of the hierarchical probing technique to efficiently evaluate the required disconnected loops. We perform nonperturbative renormalization of the axial current, including a nonperturbative treatment of the mixing between light and strange currents due to the singlet-nonsinglet difference caused by the axial anomaly. The form factor shapes are fit using the model-independent z expansion. From G(A)(q)(Q(2)), we determine the quark contributions to the nucleon spin and axial radii. By extrapolating the isovector G(P)(u-d)(Q(2)), we obtain the induced pseudoscalar coupling relevant for ordinary muon capture and the pion-nucleon coupling constant. We find that the disconnected contributions to G(P) form factors are large, and give an interpretation based on the dominant influence of the pseudoscalar poles in these form factors.

Experimental Study of Optimal Measurements for Quantum State Tomography

Sosa-Martinez, H.; Lysne, N. K.; Baldwin, C. H.; Kalev, A.; Deutsch, I. H.; Jessen, P. S. (AMER PHYSICAL SOC, 2017-10-13)

Quantum tomography is a critically important tool to evaluate quantum hardware, making it essential to develop optimized measurement strategies that are both accurate and efficient. We compare a variety of strategies using nearly pure test states. Those that are informationally complete for all states are found to be accurate and reliable even in the presence of errors in the measurements themselves, while those designed to be complete only for pure states are far more efficient but highly sensitive to such errors. Our results highlight the unavoidable trade-offs inherent in quantum tomography.

PULSAR MAGNETOSPHERES: BEYOND THE FLAT SPACETIME DIPOLE

Gralla, Samuel E.; Lupsasca, Alexandru; Philippov, Alexander (IOP PUBLISHING LTD, 2016-12-20)

Most studies of the pulsar magnetosphere have assumed a pure magnetic dipole in flat spacetime. However, recent work suggests that the effects of general relativity are in fact of vital importance and that realistic pulsar magnetic fields will have a significant nondipolar component. We introduce a general analytical method for studying the axisymmetric force-free magnetosphere of a slowly rotating star of arbitrary magnetic field, mass, radius, and moment of inertia, including all the effects of general relativity. We confirm that spacelike current is generically present in the polar caps (suggesting a pair production region), irrespective of the stellar magnetic field. We show that general relativity introduces a similar to 60% correction to the formula for the dipolar component of the surface magnetic field inferred from spindown. Finally, we show that the location and shape of the polar caps can be modified dramatically by even modestly strong higher moments. This can affect emission processes occurring near the star and may help explain the modified beam characteristics of millisecond pulsars.

THE REDMAPPER GALAXY CLUSTER CATALOG FROM DES SCIENCE VERIFICATION DATA

Rykoff, E. S.; Rozo, E.; Hollowood, D.; Bermeo-Hernandez, A.; Jeltema, T.; Mayers, J.; Romer, A. K.; Rooney, P.; Saro, A.; Cervantes, C. Vergara; Wechsler, R. H.; Wilcox, H.; Abbott, T. M. C.; Abdalla, F. B.; Allam, S.; Annis, J.; Benoit-Lévy, A.; Bernstein, G. M.; Bertin, E.; Brooks, D.; Burke, D. L.; Capozzi, D.; Rosell, A. Carnero; Kind, M. Carrasco; Castander, F. J.; Childress, M.; Collins, C. A.; Cunha, C. E.; D’Andrea, C. B.; Costa, L. N. da; Davis, T. M.; Desai, S.; Diehl, H. T.; Dietrich, J. P.; Doel, P.; Evrard, A. E.; Finley, D. A.; Flaugher, B.; Fosalba, P.; Frieman, J.; Glazebrook, K.; Goldstein, D. A.; Gruen, D.; Gruendl, R. A.; Gutierrez, G.; Hilton, M.; Honscheid, K.; Hoyle, B.; James, D. J.; Kay, S. T.; Kuehn, K.; Kuropatkin, N.; Lahav, O.; Lewis, G. F.; Lidman, C.; Lima, M.; Maia, M. A. G.; Mann, R. G.; Marshall, J. L.; Martini, P.; Melchior, P.; Miller, C. J.; Miquel, R.; Mohr, J. J.; Nichol, R. C.; Nord, B.; Ogando, R.; Plazas, A. A.; Reil, K.; Sahlén, M.; Sanchez, E.; Santiago, B.; Scarpine, V.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Stott, J. P.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Thomas, D.; Tucker, D.; Uddin, S.; Viana, P. T. P.; Vikram, V.; Walker, A. R.; Zhang, Y. (IOP PUBLISHING LTD, 2016-05-02)

We describe updates to the redMaPPer algorithm, a photometric red-sequence cluster finder specifically designed for large photometric surveys. The updated algorithm is applied to 150 deg(2) of Science Verification (SV) data from the Dark Energy Survey (DES), and to the Sloan Digital Sky Survey (SDSS) DR8 photometric data set. The DES SV catalog is locally volume limited and contains 786 clusters with richness lambda > 20 (roughly equivalent to M500c greater than or similar to 10(14) h(70)(-1)M(circle dot)) and 0.2 < z < 0.9. The DR8 catalog consists of 26,311 clusters with 0.08 < z < 0.6, with a sharply increasing richness threshold as a function of redshift for z greater than or similar to 0.35. The photometric redshift performance of both catalogs is shown to be excellent, with photometric redshift uncertainties controlled at the sigma(z)/(1+ z) similar to 0.01 level for z greater than or similar to 0.7, rising to similar to 0.02 at z similar to 0.9 in DES SV. We make use of Chandra and XMM X-ray and South Pole Telescope Sunyaev-Zeldovich data to show that the centering performance and mass-richness scatter are consistent with expectations based on prior runs of redMaPPer on SDSS data. We also show how the redMaPPer photo-z and richness estimates are relatively insensitive to imperfect star/galaxy separation and small-scale star masks.

Quantum limit in a quasi-one-dimensional conductor in a high tilted magnetic field

Lebed, A. G. (MAIK NAUKA/INTERPERIODICA/SPRINGER, 2017-10)

Recently, we have suggested Fermi-liquid-non-Fermi-liquid angular crossovers that may exist in quasi-one-dimensional (Q1D) conductors in high tilted magnetic fields (see A. G. Lebed, Phys. Rev. Lett. 115, 157001 (2015)). All calculations in the Letter were done by using the quasiclassical Peierls substitution method, whose applicability in high magnetic fields was questionable. Here, we solve a fully quantum mechanical problem and show that the main qualitative conclusions of the work cited above are correct. In particular, we show that in high magnetic fields, applied along one of the two main crystallographic axis, we have 2D electron spectrum, whereas, for directions of high magnetic fields far from the axes, we have 1D electron spectrum. The latter is known to promote non-Fermi-liquid properties. As a result, we expect the existence of Fermi-liquid-non-Fermi-liquid angular crossovers or phase transitions. Electronic parameters of Q1D conductor (Per)(2)Pt(mnt)(2) show that such transitions can appear in feasible high magnetic fields of the order of H similar or equal to 20-25 T.

Monopoles Loaded With 3-D-Printed Dielectrics for Future Wireless Intrachip Communications

Wu, Junqiang; Kodi, Avinash Karanth; Kaya, Savas; Louri, Ahmed; Xin, Hao (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2017-12)

We propose a novel antenna design enabled by 3-D printing technology for future wireless intrachip interconnects aiming at applications of multicore architectures and system-on-chips. In our proposed design we use vertical quarter-wavelength monopoles at 160 GHz on a ground plane to avoid low antenna radiation efficiency caused by the silicon substrate. The monopoles are surrounded by a specially designed dielectric property distribution. This additional degree of freedom in design enabled by 3-D printing technology is used to tailor the electromagnetic wave propagation. As a result, the desired wireless link gain is enhanced and the undesired spatial crosstalk is reduced. Simulation results show that the proposed dielectric loading approach improves the desired link gain by 8-15 dB and reduces the crosstalk by 9-23 dB from 155 to 165 GHz. As a proof-of-concept, a 60 GHz prototype is designed, fabricated, and characterized. Our measurement results match the simulation results and demonstrate 10-18 dB improvement of the desired link gain and 10-30 dB reduction in the crosstalk from 55 to 61 GHz. The demonstrated transmission loss of the desired link at a distance of 17 mm is only 15 dB, which is over 10 dB better than the previously reported work.

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