Hans Hansson

Charge fractionalization on quantum Hall edges

We discuss the propagation and fractionalization of localized charges on the edges of quantum Hall bars of variable widths, where interactions between the edges give rise to Luttinger liquid behavi ...

Time Domain Analysis of Dynamical Switching in a Josephson Junction

A Josephson junction (JJ) when is connected to an external current source via a twisted pair with impedance Z, presents a probability distribution P of switching of the JJ, as a function of the current pulse from the source. Due to quantum effects and various noise sources, such as resistive leads at finite temperatures, this distribution will have a finite width. In a qubit system, such as the Quantronium, it is necessary that this width is small in order to clearly distinguish between different quantum states, and eventually realise the single shot measurement.

Phase space topology of a switching current detector

We examine in theory and by numerical simulation, the dynamic process of switching from a zero voltage to a finite voltage state in a Josephson junction circuit. The theoretical model describes small capacitance Josephson junctions which are overdamped at high frequencies, and can be applied to detection of the quantum state of a qubit circuit. We show that the speed and fidelity of the readout are strongly influenced by the topology of the phase space attractors. The readout will be close to optimal when choosing the circuit parameters so as to avoid having an unstable limiting cycle which separates the two basins of attraction.

PAN-EURASIAN EXPERIMENT (PEEX) PROGRAM: AN OVERVIEW OF THE FIRST 5 YEARS IN OPERATION AND FUTURE PROSPECTS

The Pan-Eurasian Experiment (PEEX) program was initiated as a bottom-up approach by the researchers coming fromFinlandandRussiain October 2012. The PEEX China kick off meeting was held in November 2013. During its five years in operation, the program has established a governance structure and delivered a science plan for the Northern Eurasian region. PEEX has also introduced a concept design for a modelling platform and ground-based in situ observation systems for detecting land-atmosphere and ocean-atmosphere interactions. Today, PEEX has an extensive researcher’s network representing research communities coming from the Nordic countries,RussiaandChina. PEEX is currently carrying out its research activities on a project basis, but is looking for more coordinated funding bases, especially inRussiaand inChina. The near-future challenge in implementing the PEEX research agenda is to achieve a successful integration and identification of the methodological approaches of the socio-economic research to environmental sciences. Here we give insight into these issues and provide an overview on the main tasks for the upcoming years.

The Nobel Symposium 156 new forms of matter: topological insulators and superconductors

Eddy Ardonne Hans Hansson and Stellan Ostlund 1 Stockholm University, Sweden Chalmers University of Technology, Sweden The Nobel Symposium 156, ‘New forms of matter: topological insulators and superconductors’ took place from Friday 13 June until Sunday 15 June 2014. The venue for this Symposium was Hogberga Gard, on Lindingo, an island just east of Stockholm. The aim of the Symposium was to bring together leading scientists to discuss the latest results and important future directions in the rapidly developing field of topological states of matter. The Symposium welcomed 52 international participants, and 22 local observers. The program of the Symposium consisted of six sessions, each of which was introduced by an introductory talk, followed by shorter presentations. The last ordinary session was followed by a lively panel discussion. In these Proceedings, you will find a selection of the topics that were discussed during the Symposium. We would like to thank Petra Nodler for her invaluable administrative support, as well as the Knut and Alice Wallenberg Foundation, the Nobel Foundation, Nordita and Stockholm University, who supported this Nobel Symposium.

Nobel Symposium 148: Graphene and Quantum Matter

The 2010 Nobel Symposium on Graphene and Quantum Matter, was held at the Grand Hotel in Saltsjobaden south of Stockholm on 27–31 May. The main theme of the meeting was graphene, and the symposium turned out to be very timely: two of the participants, Andre Geim and Kanstantin Novoselov returned to Stockholm less then six months later to receive the 2010 Nobel Prize in Physics. In these proceedings leading experts give up-to-date, historical, experimental, theoretical and technological perspectives on the remarkable material graphene, and several papers also make connections to other states of quantum matter. Saltsjobaden is beautifully situated in the inner archipelago of Stockholm. It provided a pleasant setting for the talks and the ensuing discussions that took place in an enthusiastic and friendly atmosphere. The social programme included a boat trip in the light summer night and a dinner at the renowned Grand Hotel. These proceedings are ordered thematically, starting with historical overviews, followed by first experimental and then theoretical papers on the physics of graphene. Next are several papers addressing more general topics in quantum matter and finally contributions on the technological applications of graphene. We hope that this volume will serve as a source of knowledge and inspiration for any physicist interested in graphene, and at the same time provide a snapshot of a young field of research that is developing at very high speed. We are grateful to Marja Fahlander for excellent administrative support, and to the Nobel Foundation who funded the symposium.