Claes-Göran Granqvist

Bio: Claes-Göran Granqvist is an academic researcher from Uppsala University. The author has contributed to research in topics: Electrochromism & Thin film. The author has an hindex of 73, co-authored 535 publications receiving 31523 citations. Previous affiliations of Claes-Göran Granqvist include Chalmers University of Technology & Texas A&M University.

On the "Cracking" Experiments in Gunn, Allison, Abbott, "A Directional Coupler Attack Against the Kish Key Distribution System"

Abstract: Recently Gunn, Allison and Abbott (GAA) [http://arxiv.org/pdf/1402.2709v2.pdf] proposed a new scheme to utilize electromagnetic waves for eavesdropping on the Kirchhoff-law‐Johnson-noise (KLJN) secure key distribution. In a former paper [http://vixra.org/pdf/1403.0964v4.pdf], we proved that CAA's wave-based attack is unphysical. Here we address their experimental results regarding this attack. Our analysis shows that GAA virtually claim that they can identify, in a few correlation times that, from two Gaussian distributions with zero mean, which one is wider when their relative width difference is <10 -4 . Normally, such decision would need millions of correlations times to observe. We identify the experimental artifact causing this situation: existing DC current and/or ground loop (yielding slow deterministic currents) in the system. It is important to note that, while the GAA's cracking scheme, the experiments and the analysis are invalid, there is an important benefit of their attempt: our analysis implies that, in practical KLJN systems, DC currents ground loops or any other mechanisms carrying a deterministic current/voltage component must be taken care of to avoid information leak about the key.

On the “cracking” Scheme in the Paper “A Directional Coupler Attack Against the Kish Key Distribution System” by Gunn, Allison and Abbott

Abstract: Recently, Gunn, Allison and Abbott (GAA) [http://arxiv.org/pdf/1402.2709v2.pdf] proposed a new scheme to utilize electromagnetic waves for eavesdropping on the Kirchhoff-law–Johnson-noise (KLJN) secure key distribution. We proved in a former paper [http://arxiv.org/pdf/1404.4664] that GAA’s mathematical model is unphysical. Here we analyze GAA’s cracking scheme and show that in the cable loss free case it serves less eavesdropping information than the old mean-square based attack, while in the loss-dominated case it offers no information. We also investigate GAA's experimental claim to be capable of distinguishing, with a poor statistics over a few correlation times, the distributions of two Gaussian noises with a relative variance difference of less than 10–8. Normally such distinctions would require hundreds of millions of correlations times to be observable. We identify several experimental artifacts due to poor design that can lead to GAA’s assertions; deterministic currents due to spurious harmonic components ground loop, DC offset; aliasing; non-Gaussian features including non-linearities and other non-idealities in the generators; and the time-derivative nature of their scheme enhancing all these aspects.

Film electrochromique et dispositif comprenant celui-ci

Abstract: La presente invention concerne un film electrochromique represente par la formule suivante: ApBqOxXy. Dans cette formule A est un ou plusieurs elements du groupe constitue de Ni, Ir, Cr, V, Mn, Fe, W, Mo, Ti, Co, Ce, Pr et Hf; B est un ou plusieurs elements du groupe constitue de Mg, Ca, Sr, Ba, Nb, Al, Zr, Ta et Si; O est oxygene; -X est un element du groupe constitue de H, F et N, et le rapport q/p est superieur a 0,2 et inferieur a 3,5, x est superieur a 0.5(p+q) et inferieur a 5(p+q), et y est superieur ou egal a 0 et inferieur a 2x. Ce film peut aussi comprendre une quantite de Li, de Na ou de K. Cette invention concerne aussi un dispositif electrochromique comprenant au moins une couche de ce film electrochromique.

Graphene photonics and optoelectronics

Abstract: The richness of optical and electronic properties of graphene attracts enormous interest. Graphene has high mobility and optical transparency, in addition to flexibility, robustness and environmental stability. So far, the main focus has been on fundamental physics and electronic devices. However, we believe its true potential lies in photonics and optoelectronics, where the combination of its unique optical and electronic properties can be fully exploited, even in the absence of a bandgap, and the linear dispersion of the Dirac electrons enables ultrawideband tunability. The rise of graphene in photonics and optoelectronics is shown by several recent results, ranging from solar cells and light-emitting devices to touch screens, photodetectors and ultrafast lasers. Here we review the state-of-the-art in this emerging field.