Just How Final are Today's Quantum Structures?

I present a selection of conceptual and mathematical problems in the foundations of modern physics as they derive from the title question. Contribution to a panel session, "Springer Forum: Quantum Structures -- Physical, Mathematical and Epistemological Problems", held at the Biannual Symposium of the International Quantum Structures Association, Liptovsky Jan, September 1998. To appear in journal: Soft Computing (2001).Comment: 3 pages, tcilate

Complementarity and uncertainty in Mach-Zehnder interferometry and beyond

A coherent account of the connections and contrasts between the principles of complementarity and uncertainty is developed starting from a survey of the various formalizations of these principles. The conceptual analysis is illustrated by means of a set of experimental schemes based on Mach-Zehnder interferometry. In particular, path detection via entanglement with a probe system and (quantitative) quantum erasure are exhibited to constitute instances of joint unsharp, measurements of complementary pairs of physical quantities, path and interference observables. The analysis uses the representation of observables as positive-operator-valued measures (POVMs). The reconciliation of complementary experimental options in the sense of simultaneous unsharp preparations and measurements is expressed in terms of uncertainty relations of different kinds. The feature of complementarity, manifest in the present examples in the mutual exclusivity of path detection and interference observation, is recovered as a limit case from the appropriate uncertainty relation. It is noted that the complementarity and uncertainty principles are neither completely logically independent nor logical consequences of one another. Since entanglement is an instance of the uncertainty of quantum properties (of compound systems), it is moot to play out uncertainty and entanglement against each other as possible mechanisms enforcing complementarity. (c) 2006 Published by Elsevier B.V

Position Measurements Obeying Momentum Conservation

We present a hitherto unknown fundamental limitation to a basic measurement: that of the position of a quantum object when the total momentum of the object and apparatus is conserved. This result extends the famous Wigner-Araki-Yanase (WAY) theorem, and shows that accurate position measurements are only practically feasible if there is a large momentum uncertainty in the apparatus

Value-at-risk of carbon constraints : an input oriented approach of resource scarcity

The purpose of this study is to broaden the discussion on corporate enviromental risk exposure by integrating an oil scarcity factor. This broader approach can be utilized as a means of instigating a discussion on carbon risks beyond output oriented adaption and mitigation strategies. Even though the outcomes might not seem to be relevant for current economic activities, the recent discussion about oil prices affecting the global economy illustrates the future relevance of this topic; it is just a matter of time before risks related to future oil supply and endowment will emerge. --