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Aparently very interesting, will it survive the short hype? Relevant work describing mirror charges of topological insulators and the classical boundary conditions were done by Ismo and Ari. But the two communities don't know each other and so they are never cited. Also a way to produce new things...

Thanks for noticing! Indeed, I had no idea that Ari (don't know Ismo) was involved in the field. Was it before Kane's proposal or more recently? What I mostly like is that semiconductors are good candidates for 3D TI, however I got lost in the quantum field jargon. Yesterday, I got a headache trying to follow the Majorana fermions, the merons, skyrnions, axions, and so on. Luzi, are all these things familiar to you?

Ismo Lindell described in the early 90's the mirror charge of what is now called topological insulator. He says that similar results were obtained already at the beginning of the 20th century... Ismo Lindell and Ari Sihvola in the recent years discussed engineering aspects of PEMCs (perfect electro-megnetic conductors,) which are more or less classical analogues of topological insulators. Fundamental aspects of PEMCs are well knwon in high-energy physics for a long time, recent works are mainly due to Friedrich Hehl and Yuri Obukhov. All these works are purely classical, so there is no charge quantisation, no considerations of electron spin etc. About Majorana fermions: yes, I spent several years of research on that topic. Axions: a topological state, of course, trivial :-) Also merons and skyrnions are topological states, but I'm less familiar with them.

"Non-Abelian systems1, 2 contain composite particles that are neither fermions nor bosons and have a quantum statistics that is far richer than that offered by the fermion-boson dichotomy. The presence of such quasiparticles manifests itself in two remarkable ways. First, it leads to a degeneracy of the ground state that is not based on simple symmetry considerations and is robust against perturbations and interactions with the environment. Second, an interchange of two quasiparticles does not merely multiply the wavefunction by a sign, as is the case for fermions and bosons. Rather, it takes the system from one ground state to another. If a series of interchanges is made, the final state of the system will depend on the order in which these interchanges are being carried out, in sharp contrast to what happens when similar operations are performed on identical fermions or bosons." wow, this paper by Stern reads really weired ... any of you ever looked into this?

C'mon Leopold, it's as trivial as the topological states, AKA axions! Regarding the question, not me!

just looked up the wikipedia entry on axions .... at least they have some creativity in names giving: "In supersymmetric theories the axion has both a scalar and a fermionic superpartner. The fermionic superpartner of the axion is called the axino, the scalar superpartner is called the saxion. In some models, the saxion is the dilaton. They are all bundled up in a chiral superfield. The axino has been predicted to be the lightest supersymmetric particle in such a model.[24] In part due to this property, it is considered a candidate for the composition of dark matter.[25]"

Thank's Leopold. Sorry Luzi for being ironic concerning the triviality of the axions. Now, Leo confirmed me that indeed is a trivial matter. I have problems with models where EVERYTHING is involved.

Well, that's the theory of everything, isn't it?? Seriously: I don't think that theoretically there is a lot of new stuff here. Topological aspects of (non-Abelian) theories became extremely popular in the context of string theory. The reason is very simple: topological theories are much simpler than "normal" and since string theory anyway is far too complicated to be solved, people just consider purely topological theories, then claiming that this has something to do with the real world, which of course is plainly wrong. So what I think is new about these topological insulators are the claims that one can actually fabricate a material which more or less accurately mimics a topological theory and that these materials are of practical use. Still, they are a little bit the poor man's version of the topological theories fundamental physicists like to look at since electrdynamics is an Abelian theory.

I have the feeling, not the knowledge, that you are right. However, I think that the implications of this light quantum field effects are great. The fact of being able to sustain two currents polarized in spin is a technological breakthrough.

not sure how much I can contribute to your apparently educated debate here but if I remember well from my work for the master, these non-Abelian theories were all but "simple" as Luzi puts it ... and from a different perspective: to me the whole thing of being able to describe such non-Abelian systems nicely indicates that they should in one way or another also have some appearance in Nature (would be very surprised if not) - though this is of course no argument that makes string theory any better or closer to what Luzi called reality ....

Well, electrodynamics remains an Abelian theory. From the theoretical point of view this is less interesting than non-Abelian ones, since in 4D the fibre bundle of a U(1) theory is trivial (great buzz words, eh!) But in topological insulators the point of view is slightly different since one always has the insulator (topological theory), its surrounding (propagating theory) and most importantly the interface between the two. This is a new situation that people from field and string theory were not really interested in.

guys... how would you explain this to your gran mothers?

An energy scenario published by an oil company? Allow me to be sceptical...

Indeed, Shell is an energy company, not just oil, for some time now ... The two scenarii are, in their approach, dependant of economic and political situation, which is right now impossible to forecast. Reference to Kyoto is surprising, almost out-dated! But overall, I find it rather optimistic at some stages, and probably the timeline (p37-39) is unlikely with recent events.

the report was published in 2008, which explains the reference to Kyoto, as the follow-up to it was much more uncertain at that point. The Blueprint scenario is indeed optimistic, but also quite unlikely I'd say. I don't see humanity suddenly becoming so wise and coordinated. Sadly, I see something closer to the Scramble scenario as much more likely to occur.

not an oil company??? please have a look at the percentage of their revenues coming from oil and gas and then compare this with all their other energy activities together and you will see very quickly that it is only window dressing ... they are an oil and gas company ... and nothing more

not JUST oil. From a description: "Shell is a global group of energy and petrochemical companies." Of course revenues coming from oil are the biggest, the investment turnover on other energy sources is small for now. Knowing that most of their revenues is from an expendable source, to guarantee their future, they invest elsewhere. They have invested >1b$ in renewable energy, including biofuels. They had the largest wind power business among so-called "oil" companies. Oil only defines what they do "best". As a comparison, some time ago, Apple were selling only computers and now they sell phones. But I would not say Apple is just a phone company.

window dressing only ... e.g. Net cash from operating activities (pre-tax) in 2008: 70 Billion$ net income in 2008: 26 Billion revenues in 2008: 88 Billion Their investments and revenues in renewables don't even show up in their annual financial reports since probably they are under the heading of "marketing" which is already 1.7 Billion $ ... this is what they report on their investments: Capital investment, portfolio actions and business development Capital investment in 2009 was $24 billion. This represents a 26% decrease from 2008, which included over $8 billion in acquisitions, primarily relating to Duvernay Oil Corp. Capital investment included exploration expenditure of $4.5 billion (2008: $11.0 billion). In Abu Dhabi, Shell signed an agreement with Abu Dhabi National Oil Company to extend the GASCO joint venture for a further 20 years. In Australia, Shell and its partners took the final investment decision (FID) for the Gorgon LNG project (Shell share 25%). Gorgon will supply global gas markets to at least 2050, with a capacity of 15 million tonnes (100% basis) of LNG per year and a major carbon capture and storage scheme. Shell has announced a front-end engineering and design study for a floating LNG (FLNG) project, with the potential to deploy these facilities at the Prelude offshore gas discovery in Australia (Shell share 100%). In Australia, Shell confirmed that it has accepted Woodside Petroleum Ltd.'s entitlement offer of new shares at a total cost of $0.8 billion, maintaining its 34.27% share in the company; $0.4 billion was paid in 2009 with the remainder paid in 2010. In Bolivia and Brazil, Shell sold its share in a gas pipeline and in a thermoelectric power plant and its related assets for a total of around $100 million. In Canada, the Government of Alberta and the national government jointly announced their intent to contribute $0.8 billion of funding towards the Quest carbon capture and sequestration project. Quest, which is at the f

thanks for the info :) They still have their 50% share in the wind farm in Noordzee (you can see it from ESTEC on a clear day). Look for Shell International Renewables, other subsidiaries and joint-ventures. I guess, the report is about the oil branch. http://sustainabilityreport.shell.com/2009/servicepages/downloads/files/all_shell_sr09.pdf http://www.noordzeewind.nl/