Posts in category Research

are best qubits ever combining natural representation of two-level system in terms of electron spin with all advantages of superconducting qubits. This is discussed in our paper with Ciprian Padurariu submitted on cond-mat today. You will see it on Monday at http://arxiv.org/abs/0912.3910

For Ciprian, this is the first submission. It was difficult to work on the text, especially in last days. Anyway, we’ve this job done.

is a fascinating proposal of a superconducting device where phase-slips, topological instantons of superconducting order parameter, influence driven oscillations in a resonator.
If you are in resonance of any kind, and Lorentian shape of it have already become a boring habit for you, you must see our paper. As a matter of fact, we make a fascinating corkscrew out of the Lorentian, this promises some interesting applications. Read it tomorrow at http://arxiv.org/abs/0912.3699

This is the first submission of Alina Hriscu, my PhD student. To make it done, we had to work against the clock for last several days. I hope that she still catches her plane in the evening.

this work in collaboration with my Finnish colleagues Matti Laakso and Tero will appear tomorrow at http://arxiv.org/abs/0912.2832.
We looked at one of the most studied nanodevices, SE transistor. To our surprise, we have discovered a set of new effects related to temperature fluctations in the device core while it is overheated. Those are reflected in the current through the device.

There is a detail of special significance for me. I got to Delft for the first time about twenty years ago and talk to experimentalists, Bart Geerligs and Hans Mooij. They listed questions I could help them with. One was a little puzzle with freshly observed co-tunneling transport. There was a factor of two discrepancy between experiment and theory. It looks like finally we managed to resolve this puzzle: overheating must be the reason.

is quite a long title. From the other hand, the paper is also quite long. Click here to have a look.

As to research, it took more than eight years to accomplish the project. We have started it with my that time phd student Daniel Huertas-Hernando in hope to complete it quickly. However, it did not want to go that way. Wolfgang Belzig has helped us so we got a preliminary write-up in april 2002. Wolfgang has become a professor, moved to Konstanz, was having students: finally, his that time student Audrey Cottet took a banner from the hands of fallen. Without her persistance we’ve never been done.

So it’s all about spintronics and superconductors…

I have submitted today an article to Nanotechnology, for their special issue on quantum things. This is collaboration with Leo Kouwenhoven and Fabian Hassler. Fabian Hassler has recently begun a postdoc carreer between Leiden and Delft in the framework of concentration group on quantum information. He is a citizen of Lichtenstein, the only one I know. He is supposed to divide his working time between Delft (to help experimentalists) and Leiden (to do theory?). He enjoyes having an office space in both cities.

Quantum manipulation of Josephson LED was a starting project of Fabian: to play with devices that are reasonably close to those in the fridges of experimental colleagues. He has accoplished this with speed of light: eight weeks have passed since the project formulation! Now we know how to produce entangled photon pairs on demand. We plan to go futher with Josephon LED research starting new year.

 You can see the article on Monday at http://lanl.archive.org/abs/0911.5100