Monday, October 20, 2008

Quantum Criticality and Black Holes

I've always stated that the study of condensed matter physics is often as fundamental as any other other areas of physics, despite the connotation that condensed matter physics is "applied" physics and thus, not fundamental. One only needs to look at where Peter Higgs got the inspiration for the Higgs mechanism to falsify that erroneous view of condensed matter.

Well then, add this as another evidence. This article, presented as a talk (presumably by Subir Sachdev), makes a clear connection between condensed matter system and various fundamental physics in other areas of physics, including black holes physics!

Abstract: Many condensed matter experiments explore the finite temperature dynamics of systems near quantum critical points. Often, there are no well-defined quasiparticle excitations, and so quantum kinetic equations do not describe the transport properties completely. The theory shows that the transport co-efficients are not proportional to a mean free scattering time (as is the case in the Boltzmann theory of quasiparticles), but are completely determined by the absolute temperature and by equilibrium thermodynamic observables. Recently, explicit solutions of this quantum critical dynamics have become possible via the AdS/CFT duality discovered in string theory. This shows that the quantum critical theory provides a holographic description of the quantum theory of black holes in a negatively curved anti-de Sitter space, and relates its transport co-efficients to properties of the Hawking radiation from the black hole. We review how insights from this connection have led to new results for experimental systems: (i) the vicinity of the superfluid-insulator transition in the presence of an applied magnetic field, and its possible application to measurements of the Nernst effect in the cuprates, (ii) the magnetohydrodynamics of the plasma of Dirac electrons in graphene and the prediction of a hydrodynamic cyclotron resonance.

What this means is that many of the same physics in these astrophysical/String theory systems can actually, in fact, be studied via condensed matter systems. Fancy that!



Heumpje said...

Hi there,
It was indeed a talk presented by Subir Sachdev and I was sitting in the audience (25th international conference on low temperature physics, LT25). In fact the idea he proposes is slightly different. Suppose you have a fancy condensed matter problem (a system close to being quantum critical) you want to solve but don't know how to. He proposes that you can map it onto an AdS space through a duality transformation. The dynamics of the AdS space can be more easily worked out and you then use the holographic principle to map the solution back onto the one you are actually looking for.

So you are not directly probing the dynamics studied in string theory, although their theoretical understanding does (supposedly) give insight into the dynamics of systems you can prepare in a lab.

ZapperZ said...

Ah. Thanks very much for the explanation. That was very helpful!


Daniel Doro Ferrante said...

Hi ZapperZ,

Only now have i been able to catch up on some material i hadn't yet been able to read… so, that's the reason for such a late-coming comment.

I don't know where Higgs got his idea for the mechanism that nowadays carries his name. However, i do know where G. Guralnik got his idea for the mechanism that for most of the 60s and 70s was referred to as "GHK-mechanism", and later renamed as "Higgs mechanism" by B. Lee.

In fact, you should keep on the lookout, for G. Guralnik will soon post a [historic] review on the arXivs about this subject, and its similarities, or lack thereof, with the analogous condensed matter phenomena. ;-)