Self-Configuring Universal Linear Optical Component

We show how to design an optical device that can perform any linear function or coupling between inputs and outputs. This design method is progressive, requiring no global optimization. We also show how the device can configure itself progressively, avoiding design calculations and allowing the device to stabilize itself against drifts in component properties and to continually adjust itself to changing conditions. This self-configuration operates by training with the desired pairs of orthogonal input and output functions, using sets of detectors and local feedback loops to set individual optical elements within the device, with no global feedback or multiparameter optimization required. Simple mappings, such as spatial mode conversions and polarization control, can be implemented using standard planar integrated optics. In the spirit of a universal machine, we show that other linear operations, including frequency and time mappings, as well as non-reciprocal operation, are possible in principle, even if very challenging in practice, thus proving there is at least one constructive design for any conceivable linear optical component; such a universal device can also be self-configuring. This approach is general for linear waves, and could be applied to microwaves, acoustics and quantum mechanical superpositions

Fundamental Limit to Linear One-Dimensional Slow Light Structures

Using a new general approach to limits in optical structures that counts orthogonal waves generated by scattering, we derive an upper limit to the number of bits of delay possible in one-dimensional slow light structures that are based on linear optical response to the signal field. The limit is essentially the product of the length of the structure in wavelengths and the largest relative change in dielectric constant anywhere in the structure at any frequency of interest. It holds for refractive index, absorption or gain variations with arbitrary spectral or spatial form. It is otherwise completely independent of the details of the structure's design, and does not rely on concepts of group velocity or group delay

Invention under uncertainty and the threat of ex post entry

This paper proposes a theoretical framework for studying the invention of new products when demand is uncertain. In this framework, under general conditions, the threat of ex post entry by a competitor can deter invention ex ante. Asymmetric market power in the ex post market exacerbates the problem. The implications of these general results are examined in a series of examples that represent important markets in the computer industry. The first is a model that shows how an operating system monopolist, by its mere presence, can deter the invention of complements, to its own detriment as well as that of society. The implications of policies such as patent protection, price regulation, and mandatory divestiture are considered. Three additional examples consider the ability of a monopolist in one market to commit to bundling an unrelated product, a pair of horizontally differentiated firms that can add a new feature to their products, and a platform leader that can be challenged in its base market by the supplier of a complementary product.Invention, innovation, demand uncertainty, ex post entry, bundling, Intel, Microsoft, Netscape

Linear Collider Physics

The International Linear Collider has a rich physics programme, whatever lies beyond the standard model. Accurate measurement of the top quark mass is needed to constrain the model or its extensions. If there is a light Higgs boson the LHC should see it, but the ILC will pin down its characteristics and test them against model predictions. If Supersymmetric particles appear the ILC will measure a complementary set of them to those seen at the LHC, and may allow extrapolation to the Grand Unified scale. And if a strong electroweak sector is indicated the ILC will be sensitive to the presence of new structures in difermion and diboson systems up to higher masses than the direct search range of the LHC. Beyond the LHC and ILC there could be need for a multi TeV lepton collider.Comment: Plenary talk at ICHEP 2004, Beijing, 22 August 200

A Note on Adult Overwintering of Dasymutilla Nigripes in Michigan (Hymenoptera: Mutillidae)

Excerpt: Although Dasymutilla nigripes (Fabricius) is one of the more common Michigan velvet ant species, little is known about its life cycle. In his summary of mutillid life cycles, Michel (1928) indicated that mutillids of northern latitudes probably overwinter in the prepupal stage within the subterranean cells of their hymenopterous hosts. Bohart and McSwain (1939) cited prepupal overwintering as normal for Dasymutilla sackenii (Cresson) in California. However, Potts and Smith (1944), also working in California, collected overwintering adult female Dasymutilla aureola pacifica (Cresson)