State transfer in dissipative and dephasing environments

By diagonalization of a generalized superoperator for solving the master equation, we investigated effects of dissipative and dephasing environments on quantum state transfer, as well as entanglement distribution and creation in spin networks. Our results revealed that under the condition of the same decoherence rate $\gamma$, the detrimental effects of the dissipative environment are more severe than that of the dephasing environment. Beside this, the critical time $t_c$ at which the transfer fidelity and the concurrence attain their maxima arrives at the asymptotic value $t_0=\pi/2\lambda$ quickly as the spin chain length $N$ increases. The transfer fidelity of an excitation at time $t_0$ is independent of $N$ when the system subjects to dissipative environment, while it decreases as $N$ increases when the system subjects to dephasing environment. The average fidelity displays three different patterns corresponding to $N=4r+1$, $N=4r-1$ and $N=2r$. For each pattern, the average fidelity at time $t_0$ is independent of $r$ when the system subjects to dissipative environment, and decreases as $r$ increases when the system subjects to dephasing environment. The maximum concurrence also decreases as $N$ increases, and when $N\rightarrow\infty$, it arrives at an asymptotic value determined by the decoherence rate $\gamma$ and the structure of the spin network.Comment: 12 pages, 6 figure

Scaling anomaly in cosmic string background

We show that the classical scale symmetry of a particle moving in cosmic string background is broken upon inequivalent quantization of the classical system, leading to anomaly. The consequence of this anomaly is the formation of single bound state in the coupling interval \gamma\in(-1,1). The inequivalent quantization is characterized by a 1-parameter family of self-adjoint extension parameter \omega. It has been conjectured that the formation of loosely bound state in cosmic string background may lead to the so called anomalous scattering cross section for the particles, which is usually seen in molecular physics.Comment: 4 pages,1 figur

A Helicity-Based Method to Infer the CME Magnetic Field Magnitude in Sun and Geospace: Generalization and Extension to Sun-Like and M-Dwarf Stars and Implications for Exoplanet Habitability

Patsourakos et al. (Astrophys. J. 817, 14, 2016) and Patsourakos and Georgoulis (Astron. Astrophys. 595, A121, 2016) introduced a method to infer the axial magnetic field in flux-rope coronal mass ejections (CMEs) in the solar corona and farther away in the interplanetary medium. The method, based on the conservation principle of magnetic helicity, uses the relative magnetic helicity of the solar source region as input estimates, along with the radius and length of the corresponding CME flux rope. The method was initially applied to cylindrical force-free flux ropes, with encouraging results. We hereby extend our framework along two distinct lines. First, we generalize our formalism to several possible flux-rope configurations (linear and nonlinear force-free, non-force-free, spheromak, and torus) to investigate the dependence of the resulting CME axial magnetic field on input parameters and the employed flux-rope configuration. Second, we generalize our framework to both Sun-like and active M-dwarf stars hosting superflares. In a qualitative sense, we find that Earth may not experience severe atmosphere-eroding magnetospheric compression even for eruptive solar superflares with energies ~ 10^4 times higher than those of the largest Geostationary Operational Environmental Satellite (GOES) X-class flares currently observed. In addition, the two recently discovered exoplanets with the highest Earth-similarity index, Kepler 438b and Proxima b, seem to lie in the prohibitive zone of atmospheric erosion due to interplanetary CMEs (ICMEs), except when they possess planetary magnetic fields that are much higher than that of Earth.Comment: http://adsabs.harvard.edu/abs/2017SoPh..292...89

Monitoring Soil Quality to Assess the Sustainability of Harvesting Corn Stover

Harvesting feedstock for biofuel production must not degrade soil, water, or air resources. Our objective is to provide an overview of field research being conducted to quantify effects of harvesting corn (Zea mays L.) stover as a bioenergy feedstock. Coordinated field studies are being conducted near Ames, IA; St. Paul and Morris, MN; Mead, NE; University Park, PA; Florence, SC; and Brookings, SD., as part of the USDA-ARS Renewable Energy Assessment Project (REAP). A baseline soil quality assessment was made using the Soil Management Assessment Framework (SMAF). Corn grain and residue yield for two different stover harvest rates (∼50% and ∼90%) are being measured. Available soil data remains quite limited but sufficient for an initial SMAF analysis that confirms total organic carbon (TOC) is a soil quality indicator that needs to be closely monitored closely to quantify crop residue removal effects. Overall, grain yields averaged 9.7 and 11.7 Mg ha−1 (155 and 186 bu acre−1) in 2008 and 2009, values that are consistent with national averages for both years. The average amount of stover collected for the 50% treatment was 2.6 and 4.2 Mg ha−1 for 2008 and 2009, while the 90% treatment resulted in an average removal of 5.4 and 7.4 Mg ha−1, respectively. Based on a recent literature review, both stover harvest scenarios could result in a gradual decline in TOC. However, the literature value has a large standard error, so continuation of this long-term multi-location study for several years is warranted

State transfer in intrinsic decoherence spin channels

By analytically solving the master equation, we investigate quantum state transfer, creation and distribution of entanglement in the model of Milburn's intrinsic decoherence. Our results reveal that the ideal spin channels will be destroyed by the intrinsic decoherence environment, and the detrimental effects become severe as the decoherence rate $\gamma$ and the spin chain length $N$ increase. For infinite evolution time, both the state transfer fidelity and the concurrence of the created and distributed entanglement approach steady state values, which are independent of the decoherence rate $\gamma$ and decrease as the spin chain length $N$ increases. Finally, we present two modified spin chains which may serve as near perfect spin channels for long distance state transfer even in the presence of intrinsic decoherence environments $\mathcal {F}{[\rho(t)]}$.Comment: 11 pages, 11 figure

Measurement of the B0-anti-B0-Oscillation Frequency with Inclusive Dilepton Events

The $B^0$-$\bar B^0$ oscillation frequency has been measured with a sample of 23 million \B\bar B pairs collected with the BABAR detector at the PEP-II asymmetric B Factory at SLAC. In this sample, we select events in which both B mesons decay semileptonically and use the charge of the leptons to identify the flavor of each B meson. A simultaneous fit to the decay time difference distributions for opposite- and same-sign dilepton events gives $\Delta m_d = 0.493 \pm 0.012{(stat)}\pm 0.009{(syst)}$ ps$^{-1}$.Comment: 7 pages, 1 figure, submitted to Physical Review Letter

High-lying, non-yrast shell structure in Ti 52

Gamma rays from Ti52 have been studied with Gammasphere and the Fragment Mass Analyzer using reactions induced by a Ca48 beam on a Be9 target. The data have been used in combination with information from deep-inelastic reactions of Ca48 beams on a thick U238 target at an energy about 25% above the Coulomb barrier. The Ti52 level scheme was expanded considerably, and the lifetimes of some of the identified states were determined for the first time. The excitation of two protons and two neutrons outside the Ca48 core provide new tests of effective interactions in the full pf-shell model space. The positive-parity states in Ti52 were compared to theoretical predictions obtained with the GXPF1A, FPD6, and KB3G effective interactions. The comparisons favor, to a degree, the results computed with the GXPF1A interaction

γ-ray spectroscopy of the odd-odd N=Z+2 deformed proton emitter 112Cs

Gamma-ray transitions have been observed in the proton-emitting N=Z+2 (Tz=1) isotope 112Cs. The transitions have been unambiguously assigned to 112Cs by correlation with the characteristic proton decay, using the method of recoil-decay tagging with mass selection. The measured proton-decay energy and half-life are Ep=810(5) keV and T1/2=470(50) μs, respectively, which are consistent with previous measurements. Five γ-ray transitions have been observed which appear to form a rotational sequence. The energy differences between excited states in the sequence are consistent with an assignment as the favored signature of the ν(h 11/2) π(h11/2) structure. Tentative evidence for fine structure in the 112Cs proton decay is also observed

Single-particle and collective structures in Cr55 and V55

Excited states in V55 and Cr55 have been populated via pn and 2n evaporation channels, respectively, following the fusion of a Ca48 beam at 172 MeV with a Be9 target. Level schemes have been deduced for the two nuclides to excitation energies of 7467 (V55) and 12226 keV (Cr55), with spins of 27/2 + and 33/2+, respectively. Negative-parity states are compared with shell-model calculations using three different effective interactions in the full fp model space. Negative-parity levels of Cr55 are explained in terms of single-particle fp-shell configurations outside N=28 and N=32 cores. Positive-parity states in both isotopes show evidence for the involvement of neutron g9/2 configurations. In the case of Cr55, a quasirotational structure based on the 1/2+[440] Nilsson orbital is observed up to the terminating state. In V55, positive-parity states do not exhibit well-developed collective features, and the observation of octupole decays is an indication of their importance in transitions from neutron g 9/2 configurations to the fp shell. Experimental results are compared with the predictions of a traditional shell model, the projected shell model, and total-Routhian-surface calculations

Cross-shell excitations near the "island of inversion": Structure of Mg30

Excited states in Mg30 have been populated to ~6 and 5 MeV excitation energy with the C14(O18,2p) reaction. Firm spin assignments for states with J2 have been made in this nucleus. The level scheme is compared to shell-model calculations using the Universal sd effective interaction and the Monte Carlo shell model method. Calculations employing a full sd model space fail to reproduce the observed levels. The results indicate that excitations across the N=20 gap are required at relatively low excitation energy to achieve a description of the data. The incorporation of the f7/2 and p3/2 orbitals into the model space gives improved results but indicate the need for further refinement of the models to reproduce the observed spectra