Simon Krekels

The word "umbrella" derives from the French "ombrelle" (literally "shadower") as in a "parasol" (litt. "anti-sun"). In French, umbrellas are called "paraplu" (litt. "anti-rain") which is much more sensible.

CPRs for junctions transitioning from the short junction (d < ξ) to the long junction regime (d > ξ); ξ ≈ 10 sites. (a) CPRs for the phase-gradient and fixed-phase methods. (b) The evolution of the CPR maximum δφmax with junction length. The colored dots represent numerical results, and the solid and dashed black lines derive from Refs. [40] and [31] respectively. (c) The maximal values reached by the CPRs plotted against the junction length. The phase-gradient and fixed-phase methods agree remarkably well despite their difference in shape.

BdG spectrum, dispersion, CPR, and Fourier components of the CPR, as obtained with the (top row) fixed-phase and (bottom row) phase-gradient methods (see text for details). (a) The BdG spectrum for varying phase drops over the junction. The Andreev states are identified by their localization within the normal metal, and are colored gray–blue for low and high degree of localization respectively. The Andreev states are blue. (b) The dispersion relation (Eq. 13) with the Andreev bound states displayed as blue dots. The plots clearly show the raising and lowering of the Andreev states at ±k F . The dispersion is drawn for δφ = π/4 as indicated by the vertical line in (a). (c) The CPR with the dashed line showing a sinusoidal CPR as reference. (d) Fourier components of the CPRs. The phase gradient in the leads strongly affects the Josephson harmonics. The length of the junction is d ≈ 2.2 ξ.

Our paper on the self-consistent theory of Josephson junctions has now been published in Phys. Rev. B!

🔗 journals.aps.org/prb/abstract...

Many thanks to my co-authors Vukan Levajac, Kristof Moors, George Simion, and Bart Sorée!

P.S. below you can check out some of the key figures from the paper 🤓

You are on this council meme but we do not grant you the rank of master, but with quantum computing

Interesting bit of sociology: They are really studiously avoiding any mention of quantum computing. First and only mention came in the last few words of the presentation by Johansson.

Great picture, bad framing. It's not like Bohr thought GR was wrong and Einstein thought QM was wrong, and so they fought.

Einstein had trouble with the apparent non-locality of QM (which he knew from relativity could violate causality) and was therefore unsatisfied. Bohr claimed nothing was wrong.

All was now a phrensy.

Thanks for calling this one, QBD!

He never actually said that. Find the quote if you can.

It's a stupid thing to say, really. Many generations of students have been led to thinking they *shouldn't even try* to understand QM. It's a shame the idea keeps propagating.

Zo'n rariteiten zitten er wel minder en minder tussen, met dat Google en vriendjes hun modellen finetunen. Maar op een AI kookapp zit niemand te wachten denk ik.

The Vicsek model beautifully illustrates how simple interactions can lead to complex behaviour.

Simulating these kinds of things is a lot of fun, and a great way to teach students programming!

No it's not.

You give Belgians too much credit if you think they invented genocide.

She's not responsible for her great-great-great-great-grandfather, is she? She probably also isn't worth AP's special attention.

New preprint! We introduce a current-conserving treatment of Josephson junctions in BdG, and find strongly modified CPRs in some cases. Check it out!

Simon Krekels, Vukan Levajac, Kristof Moors, George Simion, Bart Sor\'ee: Current Conservation in the Self-Consistent Josephson Junction https://arxiv.org/abs/2505.09288 https://arxiv.org/pdf/2505.09288 https://arxiv.org/html/2505.09288

Verdorie, vergeten.

"With this work of Newton, people's trust in the comprehensibility of natural events was gained. This establishes its immortality."

The man had a way with words.

Everybody loves transmons

Very cool. Where did you get it?

It's Google's willow press release with parallel universe mumbo-jumbo combined with the actually impressive nature paper. I think it's well-orchestrated hype to please investors.

Heel vervelend

Colloquium 27 November 2024, 2 pm - Physics meets Computer Science

I'm tired of people trying to be smart about "the Nobel prize in physics going to AI".

Those interested in learning about the physics that went (and still goes) into developing AI can listen to this excellent talk by @ecarlon.bsky.social:

fys.kuleuven.be/english/coll...

This paper was rejected on the spot by the editor of the journal we submitted to, because we didn't mention an almost unrelated paper by one of his collaborators.

Big if true

I use this a lot, thanks!

CEO of a fracking company, really??

Simon Krekels, Christian Maes, Kasper Meerts, Ward Struyve
Zig-zag dynamics in a Stern-Gerlach spin measurement
https://arxiv.org/abs/2311.13406

I wonder why nobody is bothered by the fact that they don't know how magnets work. I mean, do *you* know how magnets work?