Navigation and guidance analysis for a Mars mission Interim study report

Error propagation program simulating earth based tracking for navigation and guidance analysis of Mars missio

Quantum walks with encrypted data

In the setting of networked computation, data security can be a significant concern. Here we consider the problem of allowing a server to remotely manipulate client supplied data, in such a way that both the information obtained by the client about the server's operation and the information obtained by the server about the client's data are significantly limited. We present a protocol for achieving such functionality in two closely related models of restricted quantum computation -- the Boson sampling and quantum walk models. Due to the limited technological requirements of the Boson scattering model, small scale implementations of this technique are feasible with present-day technology.Comment: 4 pages, 2 figure

Development of a Personal and Non-Pictorial Style in Contemporary Tapestry

Some contemporary American tapestry weavers are working in a style that deliberately breaks the link with centuries of European tapestry weaving, which most often aims to be representational or pictorial in content. While a great number of remarkable works by contemporary tapestry artists are produced in this pictorial manner and are well worth consideration and commendation, a strong case can be made for more abstract imagery. The few American tapestry weavers who consciously break from the linkage to European style have developed styles that may be said to be more American, than from other influences. By examining my own work and that of related artists, the paper will discuss how this evolution has taken place. This will include examination of influences that have driven the development of a way of working that is separate from historical tapestry imagery. Time will be spent in showing how connections to historical textiles (such as kimono, tribal rugs, Navaho and Andean textiles) are often addressed and incorporated into the tapestries. Likewise, examples of how political and social issues can be embodied, within the framework of abstract imagery, or at least imagery that is more geometric than representational. Having developed the practice of designing tapestry on the computer screen, analogies between digital and tactile are often drawn, not dissimilar to the grid of the loom. Rather than suggesting this way of working should replace European style tapestry, it is offered as an alternative to broaden the options of artistic expression

Quantum interference from remotely trapped ions

We observe quantum interference of photons emitted by two continuously laser-excited single ions, independently trapped in distinct vacuum vessels. High contrast two-photon interference is observed in two experiments with different ion species, calcium and barium. Our experimental findings are quantitatively reproduced by Bloch equation calculations. In particular, we show that the coherence of the individual resonance fluorescence light field is determined from the observed interference

Project management effectiveness: The Choice - formal or informal controls

Development failures and runaway projects in the information systems (IS) area can result in substantial losses to organizations, either financially or to a company’s reputation. One important strategy in mitigating risk is the use of effective controls over IS projects. This research investigates the effectiveness of control mechanisms in IS projects, i.e., how they have been established, applied, and how they have evolved throughout the project. We conducted an in-depth study of six information systems projects with six different project managers. We found that formal controls were adopted on project elements with clearly defined project outcomes and informal controls were adopted mainly on project elements that were unclear and often related to people. Furthermore, formal controls were dominant at project initiation and in most cases these controls became less dominant over the project duration. These formal controls were more rigorously applied in external IS projects while informal controls increased in importance throughout the project duration in internally developed projects. We found the existence of informal controls to be very important in helping ensure successful project outcomes

Entanglement of distant atoms by projective measurement: The role of detection efficiency

We assess proposals for entangling two distant atoms by measurement of emitted photons, analyzing how their performance depends on the photon detection efficiency. We consider schemes based on measurement of one or two photons and compare them in terms of the probability to obtain the detection event and of the conditional fidelity with which the desired entangled state is created. Based on an unravelling of the master equation, we quantify the parameter regimes in which one or the other scheme is more efficient, including the possible combination of the one-photon scheme with state purification. In general, protocols based on one-photon detection are more efficient in set-ups characterized by low photon detection efficiency, while at larger values two-photon protocols are preferable. We give numerical examples based on current experiments.Comment: 12 pages, 6 figure