Charge Qubit Storage and Its Engineered Decoherence via Microwave Cavity

We study the entanglement of the superconducting charge qubit with the quantized electromagnetic field in a microwave cavity. It can be controlled dynamically by a classical external field threading the SQUID within the charge qubit. Utilizing the controllable quantum entanglement, we can demonstrate the dynamic process of the quantum storage of information carried by charge qubit. On the other hand, based on this engineered quantum entanglement, we can also demonstrate a progressive decoherence of charge qubit with quantum jump due to the coupling with the cavity field in quasi-classical state.Comment: 6 pages, 4 figure

The 2010 MW 6.8 Yushu (Qinghai, China) earthquake: constraints provided by InSAR and body wave seismology

By combining observations from satellite radar, body wave seismology and optical imagery, we have determined the fault segmentation and sequence of ruptures for the 2010 Mw 6.8 Yushu (China) earthquake. We have mapped the fault trace using displacements from SAR image matching, interferometric phase and coherence, and 2.5 m SPOT-5 satellite images. Modeling the event as an elastic dislocation with three segments fitted to the fault trace suggests that the southeast and northwest segments are near vertical, with the central segment dipping 70° to the southwest; slip occurs mainly in the upper 10 km, with a maximum slip of 1.5 m at a depth of 4 km on the southeastern segment. The maximum slip in the top 1 km (i.e., near surface) is up to 1.2 m, and inferred locations of significant surface rupture are consistent with displacements from SAR image matching and field observations. The radar interferograms show rupture over a distance of almost 80 km, much larger than initial seismological and field estimates of the length of the fault. Part of this difference can be attributed to slip on the northwestern segment of the fault being due to an Mw 6.1 aftershock two hours after the main event. The remaining difference can be explained by a non-uniform slip distribution with much of the moment release occurring at depths of less than 10 km. The rupture on the central and southeastern segments of the fault in the main shock propagated at a speed of 2.5 km/s southeastward toward the town of Yushu located at the end of this segment, accounting for the considerable building damage. Strain accumulation since the last earthquake on the fault segment beyond Yushu is equivalent to an Mw 6.5 earthquake

Dispersion strengthening in vanadium microalloyed steels processed by simulated thin slab casting and direct charging: Part I - Processing parameters, mechanical properties and microstructure

A study simulating thin slab continuous casting followed by direct charging into an equalisation furnace has been undertaken based on six low carbon (0.06wt-%) vanadium microalloyed steels. Mechanical and impact test data showed properties were similar or better than those obtained from similar microalloyed conventional thick cast as rolled slabs. The dispersion plus dislocation strengthening was estimated to be in the range 80-250MPa.A detailed TEM/EELS analysis of the dispersion sized sub-15nm particles showed that in all the steels, they were essentially nitrides with little crystalline carbon detected. In the Steels V-Nb, V-Ti and V-Nb-Ti, mixed transition metal nitrides were present. Modelling of equilibrium precipitates in these steels, based on a modified version of ChemSage, predicted that only vanadium rich nitrides would precipitate in austenite but that the C/N ratio would increase through the two phase field and in ferrite. The experimental analytical data clearly points to the thin slab direct charging process, which has substantially higher cooling rates than conventional casting, nucleating non-equilibrium particles in ferrite which are close to stoichiometric nitrides. These did not coarsen during the final stages of processing, but retained their highly stable average size of ~7nm resulting in substantial dispersion strengthening. The results are considered in conjunction with pertinent published literature

The Effect of Ambient Temperature on Cold Start Urban Traffic Emissions for a Real World SI Car

The influence of ambient temperature on exhaust emissions for an instrumented Euro 1 SI car was determined. A real world test cycle was used, based on an urban drive cycle that was similar to the ECE urban drive cycle. It was based on four laps of a street circuit and an emissions sample bag was taken for each lap. The bag for the first lap was for the cold start emissions. An in-vehicle direct exhaust dual bag sampling technique was used to simultaneously collect exhaust samples upstream and downstream of the three-way catalyst (TWC). The cold start tests were conducted over a year, with ambient temperatures ranging from – 2°C to 32°C. The exhaust system was instrumented with thermocouples so that the catalyst light off temperature could be determined. The results showed that CO emissions for the cold start were reduced by a factor of 8 downstream of catalyst when ambient temperature rose from -2°C to 32°C, the corresponding hydrocarbon emissions were reduced by a factor of 4. There was no clear relationship between NOx emissions and ambient temperature. For subsequent laps of the test circuit the reduction of CO and HC emissions as a function of ambient temperature was lower. The time for catalyst light off increased by 50% as the ambient temperature was reduced. The results show that the vehicle used is unlikely to meet the new – 7oC cold start CO emission regulations

Harvesting graphics power for MD simulations

We discuss an implementation of molecular dynamics (MD) simulations on a graphic processing unit (GPU) in the NVIDIA CUDA language. We tested our code on a modern GPU, the NVIDIA GeForce 8800 GTX. Results for two MD algorithms suitable for short-ranged and long-ranged interactions, and a congruential shift random number generator are presented. The performance of the GPU's is compared to their main processor counterpart. We achieve speedups of up to 80, 40 and 150 fold, respectively. With newest generation of GPU's one can run standard MD simulations at 10^7 flops/$.Comment: 12 pages, 5 figures. Submitted to Mol. Si

Finite-Element Discretization of Static Hamilton-Jacobi Equations Based on a Local Variational Principle

We propose a linear finite-element discretization of Dirichlet problems for static Hamilton-Jacobi equations on unstructured triangulations. The discretization is based on simplified localized Dirichlet problems that are solved by a local variational principle. It generalizes several approaches known in the literature and allows for a simple and transparent convergence theory. In this paper the resulting system of nonlinear equations is solved by an adaptive Gauss-Seidel iteration that is easily implemented and quite effective as a couple of numerical experiments show.Comment: 19 page

Dynamics with Infinitely Many Time Derivatives and Rolling Tachyons

Both in string field theory and in p-adic string theory the equations of motion involve infinite number of time derivatives. We argue that the initial value problem is qualitatively different from that obtained in the limit of many time derivatives in that the space of initial conditions becomes strongly constrained. We calculate the energy-momentum tensor and study in detail time dependent solutions representing tachyons rolling on the p-adic string theory potentials. For even potentials we find surprising small oscillations at the tachyon vacuum. These are not conventional physical states but rather anharmonic oscillations with a nontrivial frequency--amplitude relation. When the potentials are not even, small oscillatory solutions around the bottom must grow in amplitude without a bound. Open string field theory resembles this latter case, the tachyon rolls to the bottom and ever growing oscillations ensue. We discuss the significance of these results for the issues of emerging closed strings and tachyon matter.Comment: 46 pages, 14 figures, LaTeX. Replaced version: Minor typos corrected, some figures edited for clarit