Is Quantum Reduction the Ultimate Outcome of Decoherence ?

This model was crazy (or not crazy enough for this topic) and it would lead to a reduction time much longer than the age of the universe.Comment: This paper has been withdraw

Error estimates for a finite volume method for the Laplace equation in dimension one through discrete Green functions.

International audienceThe cell-centered finite volume approximation of the Laplace equation in dimension one is considered. An exact expression of the error between the exact and numerical solutions is derived through the use of continuous and discrete Green functions. This allows to discuss convergence of the method in the L infinity and L2 norms with respect to the choice of the control points in the cells and with respect to the regularity of the data. Well-known second-order convergence results are recovered if those control points are properly chosen and if the data belongs to H1. Counterexamples are constructed to show that second-order may be lost if these conditions are not met

Anomalies of weakened decoherence criteria for quantum histories

The theory of decoherent histories is checked for the requirement of statistical independence of subsystems. Strikingly, this is satisfied only when the decoherence functional is diagonal in both its real a n d imaginary parts. In particular, the condition of consistency (or weak decoherence) required for the assignment of probabilities appears to be ruled out. The same conclusion is obtained independently, by claiming a plausible dynamical robustness of decoherent histories.Comment: 3pp, submitted to Phys. Rev. Let

Young Europeans ́ Forum 2019 “Building Bridges for Social Cohesion”

In many European societies, social cohesion is challenged by megatrends, such as globalization, digitalization, growing inequality, and migration. In addition – or in part as a consequence of those megatrends – our living together is confronted with increasing cultural diversity, a greater plurality of values and lifestyles, as well as a rise in populism, polarization and a loss of confidence in democracy. Recognizing that many European countries face these challenges, a number of important questions arise: What holds societies together? What must we do today so that this cohesiveness will remain present in the future? How can we foster social cohesion

Decoherence of domains and defects at phase transitions

In this further letter on the onset of classical behaviour in field theory due to a phase transition, we show that it can be phrased easily in terms of the decoherence functional, without having to use the master equation. To demonstrate this, we consider the decohering effects due to the displacement of domain boundaries, with implications for the displacement of defects, in general. We see that decoherence arises so quickly in this event, that it is negligible in comparison to decoherence due to field fluctuations in the way defined in our previous papers.Comment: Version published in Phys. Lett.

Micrometre-scale refrigerators

A superconductor with a gap in the density of states or a quantum dot with discrete energy levels is a central building block in realizing an electronic on-chip cooler. They can work as energy filters, allowing only hot quasiparticles to tunnel out from the electrode to be cooled. This principle has been employed experimentally since the early 1990s in investigations and demonstrations of micrometre-scale coolers at sub-kelvin temperatures. In this paper, we review the basic experimental conditions in realizing the coolers and the main practical issues that are known to limit their performance. We give an update of experiments performed on cryogenic micrometre-scale coolers in the past five years