Quantum Coherence Lab

Zumbühl Group

 

News from our Group

Work on the European Microkelvin Platform (EMP) infrastructures proposal in Heidelberg

After hours of deliberations, changes and small-group work sessions, it's quite energizing to see the progress on the proposal achieved in the past three days in Heidelberg on the European Microkelvin Platform EMP!!

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Symmetry Breaking of the Persistent Spin Helix in Quantum Transport appeared on arXiv!

In this work, we show that the physics of the quantum corrections to the conductivity around the persistent spin helix symmetry point can be treated very similar to the case with weak spin-orbit (SO) coupling, where the small parameter is the deviation from the PSH point due to either the mismatch a-b of the Rashba a and Dresselhaus b linear terms or due to the cubic SO term b3. This similarity makes it possible to derive closed-form equation for the weak (anti)localization magnetoconductivity including all these SO terms, which turns out to be identical in form to the well-known Hikami-Larkin-Nagaoka expression, but is now reparametrized im terms of the small parameters a-b and b3. Further, we perform quantum transport experiments in the same PSH regime, and develop a reliable two-step method to extract all parameters from fits to the new expression, obtaining excellent agreement with other recent experiments. This provides experimental confirmation of the new theory, and helps advancing SO coupling towards a powerful resource in emerging quantum technologies. Weigele et al. arXiv:1801.05657.

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Coldest chip of the world went viral!!

Telebasel, Radio NRJ, Deutschlandfunk, Spiegel online, Newsweek, various Swiss, German and Austrian news papers, and even the Basel trams were featuring it, see picture... our low temperature record on a chip got a lot of attention!

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Group Dinner, Wednesday night, Dec 20, 2017

Really nice and fun group dinner last night, with some graduates coming back as well as a few select guests: great to see graduates Dorothee, Dario, Florian, and Tobias! And of course the two most recent doctors Mario and Pirmin! Great timing to have the "coldest chip of the world" appear on APL and UniNews on the same day! Great work: Christian, Mario and Dario and all coauthors! It was apparently all over Basel and the news media yesterday and today! Thanks also to all the group guests: Marta, Ilaria, Jelena, Floris and Daniel. Excellent meal, wonderful wine, and great atmosphere and, most of all, amazing speeches by everyone! Thanks very much for a wonderful evening! And a happy & successful new year!

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Low temperature record published in APL as an Editor's pick, with Scilight!

A Coulomb blockade thermometer was cooled to 2.8 mK with on-and-off chip magnetic refrigeration performed on a pulse tube dilution refrigerator platform... working towards new physics at ultralow temperatures. Published in Applied Physics Letters as an Editor's pick. See also UniNews, and featured in an AIP Scilight articlce!

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