EUROFLUX 2009

If you are passionate about fine wine, cheese, and superconducting digital electronics, you may wish to attend the EUROFLUX 2009 conference taking place in beautiful Avignon in the South of France.

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Although Euroflux is based on a European framework, the conference is international, and people are welcome to attend. You can read my review of EUROFLUX2008 here.

The abstract deadline is Monday!! See you there 😉

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Savoie experimental superconducting electronics workshop

At the moment I’m attending an S-Pulse superconducting electronics (SCE) workshop at the University of Savoie in Chambery, France.

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So far we’ve had talks about single photon detectors, hot electron bolometers, junction measurements, ballistic readout of qubits, Terahertz imaging, modelling inductances and superconducting circuits, cryocooling and cryopackaging, and plenty of RSFQ related information.

Yesterday morning we had an invited talk given by Hideo Suzuki from ISTEC, Japan, entitled ‘Progress of the interface circuit and cryopackaging techniques for SFQ circuits’. The Japanese progress on RSFQ technology is very impressive, the presented results demonstrated some very high speeds with very low Bit Error Rates (BER).

The weather is lovely and the food is delicious which always helps 🙂

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Part of the idea of S-Pulse is to get people involved in the RSFQ/SCE scene, and to disseminate information about superconducting digital electronics and why it is useful. So if you are interested in attending or contributing to a workshop, you can check out the S-PULSE website for information. So far people are meeting and networking within this European project from Germany, France, UK, Sweden, South Africa, The Netherlands and Italy, to establish the position of Europe in the field of SCE and to promote the European superconducting device foundry. Note: People from outside Europe are also encouraged to attend.

Also, there is a postdoc position and a couple of PhD positions currently available in RSFQ. More information can be found here.

EUROFLUX2008

I’ve just returned from the EUROFLUX2008 conference in Naples. The conference dealt with two main aspects of superconducting electronics: Fundamental device progress and superconducting devices as detectors. (I was mainly in with the first bunch).

A few conference highlights:

Devices

Valery Ryazanov gave a good presenation on the progress of pi junction applications for digital and quantum logic. The measurements suggest good quality qubits containing SFS (Superconductor-Ferromagnet-Superconductor) pi junction components have been fabricated. This is something I’m really pretty interested in. For RSFQ applications, pi junctions are useful as they act as phase inverters. In the case of qubits, a pi element can introduce a phase shift across one of the Josephson junctions in the loop. The ground state of the qubit loop will then consist of a spontaneously generated circulating current, a half-integer magnetic flux quantum in the loop, and most importantly a double well potential for no applied bias (aka a free lunch). Such qubits are intrinsically thought to be more ‘quiet’ – as you do not need to apply a flux bias to bring them to the working point. The presentation at the conference gave evidence that pi-qubits may be as good as conventional ‘zero’ types. And because they are Niobium SFS, they are (somewhat) compatible with existing process technology, and the best thing is that they’re low Tc, avoiding all that HTS messiness.

I think people still slightly hesitant that magnetic materials and superconductors would ever work in harmony (I spent a year investigating spin-injection devices and came to the same conclusion), not to mention the fact that having magnetic impurities all over the place is not really ideal for a component that’s incredibly sensitive to variations in field. Yet somehow they work. Go physics. Absolutely fantastic progress in this field.

See here, here, here, here and here for a few papers on SFS junctions (there are loads more).

Maria Castellano – High Frequency coherent oscillations of a flux qubit manipulated by fast pulses. The experiment involves Niobium tunable flux qubits. A superconducting loop interrupted by a double Josephson Junction loop (DC SQUID) gives you two handles on the shape of the double well potential – the barrier height and the asymmetry (bias). The group demonstrate coherent oscillations between 6-25Ghz. Operating the qubit at high frequencies means you get more oscillations for your money, and thus more (potential) ops in those vital nanoseconds before decoherence kicks in.
See here and here for some more info.

Detectors

IPHT (Jena) are developing THz cameras for security applications.
The cameras scan people passively (e.g. at airports) and can detect hidden items. Metallic items e.g. guns, knives etc. block the THz emission from the human body, causing them to appear as shadowed regions to the camera. The detector can also detect non-metallic ‘suspect’ items. These cameras are really coming along, and I perhaps fully working systems will become commonplace within the next 5 years or so. You can read more about the progress here.

SQUIDs for magnetic exploration, again from IPHT. These guys hang a cryocooler containing a SQUID from a helicopter and raster-scan the ground to detect magnetic objects. Items of interest could be unexploded landmines, large mineral deposits, or the buried remains of medieval structures.

Conference

The social event was a visit to the excavated city of Herculaneum, buried by the eruption of Mount Vesuvius in 79 AD. It was rather cool to see all the roman technology of the time.
In true Italian style, the conference dinner was an epic six-course meal. The food in general was fantastic, and the weather in Italy was also great (I think we left just before it began to get really hot). Naples itself seemed to have lots of palm trees:

It was a very useful experience overall, and the conference was small enough that nearly all the talks were relevant to my own areas of interest. The general idea of the conference was a gathering of all the people involved in superconducting electronics in Europe (although the conference was open to an international audience) to further progress in the FLUXONICS project, in the area of Niobium Josephson junction applications, and in the European RSFQ technology.

FLUXONICS

FLUXONICS is a european framework dedicated to furthering research into superconducting electronics and digital circuits. Within this framework is the S-Pulse project, which I am currently involved in. As part of this project, I recently visited the FLUXONICS foundry for superconducting electronics at IPHT, Jena for a Technology training workshop.

There are several institutions involved in the project, and it was interesting to meet people from all over Europe who share a similar interest in this technology:

University of Twente (The Netherlands)
PTB (Germany)
Chalmers Univ. of Technology (Sweden)
University of Savoie (France)
University of Cambridge (UK)
University of Birmingham (UK)
CNR-Istituto di Cibernetica (Italy)
University of Technology Ilmenau (Germany)
IPHT (Germany)
University of Karlsruhe (Germany)
CEA-Grenoble (France)

It was a good workshop, with a thorough introduction to RSFQ and the state of superconducting electronics in Europe. The foundry has a stable 1 kA/cm2 Nb/Al-AlOx/Nb process certified with ISO-9001 standard. It is nice to see this activity in Europe, given that the other two major superconducting electronics foundries are based in America (HYPRES) and Japan (ISTEC). It will be interesting to see how the European RSFQ / Josephson technology improves over the next couple of years, and to keep track of the research performed with chips fabricated using the IPHT Niobium process.