Quantum state engineering using conditional measurement on a beam splitter

State preparation via conditional output measurement on a beam splitter is studied, assuming the signal mode is mixed with a mode prepared in a Fock state and photon numbers are measured in one of the output channels. It is shown that the mode in the other output channel is prepared in either a photon-subtracted or a photon-added Jacobi polynomial state, depending upon the difference between the number of photons in the input Fock state and the number of photons in the output Fock state onto which it is projected. The properties of the conditional output states are studied for coherent and squeezed input states, and the probabilities of generating the states are calculated. Relations to other states, such as near-photon-number states and squeezed-state-excitations, are given and proposals are made for generating them by combining the scheme with others. Finally, effects of realistic photocounting and Fock-state preparation are discussed.Comment: 8 figures using a4.st

Review of \u3ci\u3eThe Ranchers: A Book of Generations\u3c/i\u3e By Stan Steiner

There is a story in the Wyoming WP A files (for which I thank James Dow of Iowa State University) about some cowboys who collapsed in various sections of a country cemetery after a full-blown drunk. One of the celebrants had fallen into a two-foot depression of a collapsed grave and there slept off his condition. He woke up at the crack of dawn, sat up in the grave, surveyed his situation, and shouted, Hurray! It\u27s Halleluja Morning and I\u27m the first one here! In The Ranchers Steiner presents us with a long, fragmented, maudlin obituary for a culture just about as moribund as that cowboy. He jumps from one narrator to another in an erratic manner that reduces the book to bathroom reading. We are given only the vaguest impression of ranching and ranchers, and an incorrect impression at that. These ranchers and Steiner, unlike ranchers I know, are in a constant funk, lamenting the loss of those good old days. Steiner and his informants seem to accept the conclusions of all those movies in which the nesters-hardy yeomen-push fences and thus civilization right over the top of the wild and free cattlemen. Well, look again. After spending a futile year or two trying to farm ranch land, a good proportion of those frontier dirt farmers sold out, and the land then reverted to grassland ranching. Steiner is like some of my Nebraska students who, straining at making Nebraska modern, laugh at the European or easterner who is silly enough to think there are still cowboys and Indians in Nebraska-missing the point that there are indeed cowboys and Indians in Nebraska. If you close your eyes, you can make anything disappear, and in this book Steiner has closed his eyes to a vital and vibrant American subculture. He has neither employed the techniques of scientifIc oral historians nor taken advantage of the freedom of the popular oral historian. The result is a confusion, with little poetry, little substance. The Ranchers serves no audience well

Quantum local-field corrections and spontaneous decay

A recently developed scheme [S. Scheel, L. Knoll, and D.-G. Welsch, Phys. Rev. A 58, 700 (1998)] for quantizing the macroscopic electromagnetic field in linear dispersive and absorbing dielectrics satisfying the Kramers-Kronig relations is used to derive the quantum local-field correction for the standard virtual-sphere-cavity model. The electric and magnetic local-field operators are shown to be consistent with QED only if the polarization noise is fully taken into account. It is shown that the polarization fluctuations in the local field can dramatically change the spontaneous decay rate, compared with the familiar result obtained from the classical local-field correction. In particular, the spontaneous emission rate strongly depends on the radius of the local-field virtual cavity.Comment: 7 pages, using RevTeX, 4 figure