From Cbits to Qbits: Teaching computer scientists quantum mechanics

A strategy is suggested for teaching mathematically literate students, with no background in physics, just enough quantum mechanics for them to understand and develop algorithms in quantum computation and quantum information theory. Although the article as a whole addresses teachers of physics, well versed in quantum mechanics, the central pedagogical development is addressed directly to computer scientists and mathematicians, with only occasional asides to their teacher. Physicists uninterested in quantum pedagogy may be amused (or irritated) by some of the views of standard quantum mechanics that arise naturally from this unorthodox perspective.Comment: 19 pages, no figures. Submitted to the American Journal of Physic

Nonlocal character of quantum theory?

In a recent article under the above title (but without the question mark) Henry Stapp presented arguments which lead him to conclude that under suitable conditions ``the truth of a statement that refers only to phenomena confined to an earlier time'' must ``depend on which measurement an experimenter freely chooses to perform at a later time.'' I point out that the reasoning leading to this conclusion relies on an essential ambiguity regarding the meaning of the expression ``statement that refers only to phenomena confined to an earlier time'' when such a statement contains counterfactual conditionals. As a result the argumentation does not justify the conclusion that there can be frames of reference in which future choices can affect present facts. But it does provide an instructive and interestingly different opportunity to illustrate a central point of Bohr's reply to Einstein, Podolsky, and Rosen.Comment: 11 pages, no figure

The Value of Existence

One does not read Beating Hearts passively. I found myself agreeing often, disagreeing often, and sometimes doing both at the same time. Just as frequently, the book made me reexamine my views from a perspective I had not considered before. For example, prior to reading the book, I had not explored the basis for my belief that causing the death of a living being is a morally significant act. The authors (with a post-mortem assist from Epicurus) have seen to that deficiency. This forum seems an ideal place to push that discussion a bit further

Deconstructing Dense Coding

The remarkable transmission of two bits of information via a single qubit entangled with another at the destination, is presented as an expansion of the unremarkable classical circuit that transmits the bits with two direct qubit-qubit couplings between source and destinationComment: 3 pages, 2 figure

The Microwave Background Bispectrum, Paper I: Basic Formalism

In this paper, we discuss the potential importance of measuring the CMB anisotropy bispectrum. We develop a formalism for computing the bispectrum and for measuring it from microwave background maps. As an example, we compute the bispectrum resulting from the 2nd order Rees-Sciama effect, and find that is undetectable with current and upcoming missions.Comment: 18 Pages, 3 Postscript Figures; Minor changes in response to referee's repor