Monday, November 14, 2011

The Regensburg nanotube team is growing!

A lot of things have happened recently in our nanotube / nanomechanics research group in Regensburg... First of all, I'd like to congratulate Peter Stiller for finishing off his Diploma thesis and thereby his degree. Peter is immediately continuing as a PhD student, however switching topic from nanomechanics to charge qubits in carbon nanotubes - a newly founded project in the SFB 631. Here we plan to couple electronic quantum states in carbon nanotube double quantum dots to the electric field of a coplanar microwave resonator.
Then, straight from München and the research group of Jan von Delft, Alois Dirnaichner will join us soon as PhD student to work on experimental and theoretical characterization of few-electron states in ultraclean suspended carbon nanotubes. This is a project pursued together with the groups of Milena Grifoni and Christoph Strunk; we hope that the high quality of our carbon nanotubes enables us to do fundamental observations and analysis on unperturbed electronic multi-particle states.
Next, Sabine Kugler joins the nanomechanics team for her MSc thesis project. She will continue the development of chip geometries and materials suitable for combining carbon nanotubes with complex electronics, and help us with the characterization measurements.
Finally, last but not least, Hermann Kraus starts in december as a Diploma student, and will focus on high-frequency electronics at very low temperatures and superconducting nanocircuitry. Time to get these electrons rock'n'roll!

Real online dilfridge :)

By the way, I just found out there's a real dilfridge (dilution refrigerator) live on twitter... :) Would be interesting to know which research group that is. With the hard-soldered caps on the top IVC plate and the ribbon cables this is for sure an Oxford Instruments model, but whatever else is visible in the lab looks like pretty standard equipment...

Sunday, November 13, 2011

KDE 4.7.3 - Identifying Plasma crashes with Gentoo

One of the less pleasant surprises about KDE 4.7.3 was that somehow "upstream" managed to introduce quite some stability regressions in the Plasma desktop. On both my laptop and my work desktop it kept crashing every now and then. This usually does not cause big problems as Plasma is immediately restarted by some KDE magic, however it can be quite annoying (in the British sense). Which is why by now we have kde-base/plasma-workspace-4.7.3-r2 in the Gentoo portage tree, where the worst offenders should be fixed by backporting from future 4.7.4. Please upgrade and test...
A related question is of course, if Plasma crashes, how do I get any more information on the origin of the problem? Usually the KDE crash reporter DrKonqui does not pop up... For diagnosis, you'll have to enable debug info while building, and core dumps while running the software. For doing both in Gentoo we have an excellent howto, which also documents how you use gdb to extract the backtrace information. Then, if you report the bug, please paste the backtrace; only that makes it possible to identify the exact problem that caused the crash! Happy hunting!

Sunday, November 6, 2011

Gentoo KDE stabilization and the KDE overlay

Here's two small news items that may be worth your attention.
First of all, we (as the Gentoo KDE team) have to decided to change our stabilization target from 4.7.2 to 4.7.3 - the main reason being that there have been many stability improvements e.g. in KDEPIM. This also means that for now the stabilization process is on hold, since version 4.7.3 needs some time to "ripen on the tree". Anyway, feel free to grab the stabilization list from bug 388279 and try it out. Most likely the list will still be updated a few times for minor fixes.
Second, if you are using the Gentoo KDE overlay, it has now been migrated to so-called thin manifests. This makes using git way easier for us committers. You as a user will however need sys-apps/portage from ~arch, because the current stable version does not support the new Manifest file format yet. This may sound like a dangerous requirement, but actually most the devs use testing portage and do not encounter any big problems. I'm running sys-apps/portage- here and all is fine.