Pure emitter dephasing : a resource for advanced solid-state single photon sources

We have computed the spectrum emitted spontaneously by a quantum dot coupled to an arbitrarily detuned single mode cavity, taking into account pure dephasing processes. We show that if the emitter is incoherent, the cavity can efficiently emit photons with its own spectral characteristics. This effect opens unique opportunities for the development of devices exploiting both cavity quantum electrodynamics effects and pure dephasing, such as wavelength stabilized single photon sources robust against spectral diffusion.Comment: 5 pages, 3 figure

Trois bicentenaires : Hume, Condillac, Smith. Adam Smith entre le marginalisme et le marxisme

It is not easy to understand why, and how, orthodox economists who do not believe either in the labor-theory or in the cost-theory of value, continue to favor Adam Smith's Wealth of Nations, but forget such economists as Condillac, whose value theory is nearer to theirs and whose bicentenary we also commemorate.Adam Smith, it is submitted, is still interesting but for reasons far enough from orthodox economic theory. Smith is in fact, according to some recent interpretations, more of a welfare economist, concerned with moral values, than a partial analysis economist: his theory of value derives from ethical considerations following Hume and keeps its normative flavor throughout instead of being solely a tentative explanation of prices. Some apparently contradictory assertions about value could thus be reconciled in a unifying theory, as explained by such authors as Lindgren (1973) or Rieseman (1976).If it is possible to reconcile many apparently contradictory views in Adam Smith's works, thanks to a more holistic approach, it is suggested that a similar approach could be applied to a more controversial economist, Karl Marx, whose career may be compared to that of Smith in many respects

L’entrepreneur dans la pensée économique : l’originalité méconnue de Turgot

Cette note remonte jusqu’à Léon Say en 1877 pour déceler une erreur répétée par Schumpeter et des auteurs contemporains qui négligent d’attribuer à A.-R.-J. Turgot la priorité dans la distinction entre capitalistes et entrepreneurs. Quelque cinquante ans avant Jean-Baptiste Say, Turgot avait explicité cette distinction, logiquement et historiquement, en se fondant sur l’absentéisme graduel de la classe des propriétaires dans la montée du capitalisme. La distinction se trouve à l’article LXX des Réflexions.This note pretends that because of an error going back at least to Léon Say (1877) and repeated by Schumpeter and contemporary authors, the priority of the 1766 "Reflexions..." of A.R.J. Turgot on the distinction between the capitalist and the entrepreneur is neglected. Some fifty years before Jean-Baptiste Say, Turgot made clear that distinction, which came logically and historically for him from the gradual absenteeism of the class of proprietors during the rise of capitalism. The distinction is found in Reflexion LXX

Théorie du bien-être et politique économique

After facing disappearance during the thirties, under the well known attack by Lionel Robbins and other economists, theoretical welfare economics seems to be more and more in use in spite of still shaky foundations. The concept of surplus, the measurement of preferences and the economic welfare function are apparently among the most promising approaches. Welfarists like Tinbergen and Bergson are not so far now from known anti-welfarists like Robbins and Myrdal. However, the issue of the debate between Pigou and Robbins has to be reconsidered before we can use welfare theory. New methodological arguments are presented that try to separate the shaft from the weed in the thesis of Pigou and Robbins. Some errors are found that have remained alive up to now. After a new light is shed on the controversy, it is fairly easy reconcile Pigou, Robbins, Bergson, Myrdal and Tinbergen. It is fortunate that we can reach such a consensus because the theory of economic policy badly needs renewed foundations to be able to cope with changing values, new patterns of distribution and other long range problems. A fresh start with the questions raised by welfare economics should ease the way towards these goals

Retour à Adam Smith (1723-1790) après deux siècles?

Après un survol des appréciations courantes de l’analyse économique de Smith, on souligne l’intérêt actuel marqué pour la totalité du système incluant d’autres niveaux comme l’histoire, la sociologie et l’éthique. Le plus intéressant de Smith pour les années à venir semble résider bien plus dans ses positions éthiques que dans son analyse économique. En fait, le principal problème pendant actuellement est celui d’une éthique acceptable de la répartition, qui ne semble résider ni dans les théories déontologiques, ni dans l’utilitarisme, mais quelque part entre les deux, comme nous convainc facilement un rapide coup d’oeil sur les positions récentes allant de Hare à Sen en passant par Rawls. La priorité accordée par Smith à d’autres motifs de deux sortes et à deux niveaux au lieu de l’utilité nous donne enfin une vision alternative à l’utilitarisme grâce à des prémisses qui appartiennent maintenant à trois niveaux de généralité et d’universalité. À cause de son naturalisme, cependant, Smith ne nous offre pas de suggestions précises pour expliciter ce système et nous permettre enfin une méthode pour souder n’importe quel système philosophique et pas seulement l’utilitarisme à la théorie économique.After a review of current assessments of Smithian economics, the author stresses the interest of the entire system at historical, sociological and ethical levels. The renewed interest in Smith comes from his ethical positions rather than from his skills as an economic analyst. The solution to the vexing problem of ever finding an acceptable ethics in distribution theory seems to be found somewhere between utilitarian and deontological theories. But neither of these two theories alone succeeds in doing so, as one is easily convinced from a short survey of the existing literature ranging from Hare to Rawls and then to Sen. The priority given by Smith to motives of two kinds at two levels different from utility permits one to have an alternative view to utilitarianism for kinds of ethical premises which belong to three levels of generalization and universalization. His naturalism does not permit one to go very far in that direction however, and much work has still to be done to bridge economics to philosophical systems other than, and distinct from, utilitarianism

X-rays from Saturn: A study with XMM-Newton and Chandra over the years 2002-05

We present the results of the two most recent (2005) XMM-Newton observations of Saturn together with the re-analysis of an earlier (2002) observation from the XMM-Newton archive and of three Chandra observations in 2003 and 2004. While the XMM-Newton telescope resolution does not enable us to resolve spatially the contributions of the planet's disk and rings to the X-ray flux, we can estimate their strengths and their evolution over the years from spectral analysis, and compare them with those observed with Chandra. The spectrum of the X-ray emission is well fitted by an optically thin coronal model with an average temperature of 0.5 keV. The addition of a fluorescent oxygen emission line at ~0.53 keV improves the fits significantly. In accordance with earlier reports, we interpret the coronal component as emission from the planetary disk, produced by the scattering of solar X-rays in Saturn's upper atmosphere, and the line as originating from the Saturnian rings. The strength of the disk X-ray emission is seen to decrease over the period 2002 - 2005, following the decay of solar activity towards the current minimum in the solar cycle. By comparing the relative fluxes of the disk X-ray emission and the oxygen line, we suggest that the line strength does not vary over the years in the same fashion as the disk flux. We consider possible alternatives for the origin of the line. The connection between solar activity and the strength of Saturn's disk X-ray emission is investigated and compared with that of Jupiter. We also discuss the apparent lack of X-ray aurorae on Saturn and conclude that they are likely to lie below the sensitivity threshold of current Earth-bound observatories. A similar comparison for Uranus and Neptune leads to the same disappointing conclusion.Comment: 10 pages, 5 figures; to be published in 'Astronomy and Astrophysics

L’entrepreneur dans la pensée économique : l’originalité méconnue de Turgot

This note pretends that because of an error going back at least to Léon Say (1877) and repeated by Schumpeter and contemporary authors, the priority of the 1766 "Reflexions..." of A.R.J. Turgot on the distinction between the capitalist and the entrepreneur is neglected. Some fifty years before Jean-Baptiste Say, Turgot made clear that distinction, which came logically and historically for him from the gradual absenteeism of the class of proprietors during the rise of capitalism. The distinction is found in Reflexion LXX. Cette note remonte jusqu’à Léon Say en 1877 pour déceler une erreur répétée par Schumpeter et des auteurs contemporains qui négligent d’attribuer à A.-R.-J. Turgot la priorité dans la distinction entre capitalistes et entrepreneurs. Quelque cinquante ans avant Jean-Baptiste Say, Turgot avait explicité cette distinction, logiquement et historiquement, en se fondant sur l’absentéisme graduel de la classe des propriétaires dans la montée du capitalisme. La distinction se trouve à l’article LXX des Réflexions.

Théorie du bien-être et politique économique

After facing disappearance during the thirties, under the well known attack by Lionel Robbins and other economists, theoretical welfare economics seems to be more and more in use in spite of still shaky foundations. The concept of surplus, the measurement of preferences and the economic welfare function are apparently among the most promising approaches. Welfarists like Tinbergen and Bergson are not so far now from known anti-welfarists like Robbins and Myrdal. However, the issue of the debate between Pigou and Robbins has to be reconsidered before we can use welfare theory. New methodological arguments are presented that try to separate the shaft from the weed in the thesis of Pigou and Robbins. Some errors are found that have remained alive up to now. After a new light is shed on the controversy, it is fairly easy reconcile Pigou, Robbins, Bergson, Myrdal and Tinbergen. It is fortunate that we can reach such a consensus because the theory of economic policy badly needs renewed foundations to be able to cope with changing values, new patterns of distribution and other long range problems. A fresh start with the questions raised by welfare economics should ease the way towards these goals.