Electromagnetic properties of viscous charged fluids
Davide Forcella (Université Libre de Bruxelles)
Recently the gauge/gravity correspondence has provided new interesting applications to high energy strongly coupled plasmas and strongly correlated condensed matter systems. At the same time, in an apparently unrelated field, there have been enormous progresses in the ability to engineer electromagnetic devices with exotic properties: such as negative refraction (energy and phase velocity for the electromagnetic field in the medium are in opposite directions), cloaking, photonics black-holes, etc.
In the talk, building on these two recent developments, I will discuss the electromagnetic properties of viscous charged fluids, consisting for example of electrons in certain solids or high energy physics plasmas. In particular I will show that finite viscosity leads to multiple modes of evanescent electromagnetic waves at a given frequency, one of which is characterised by a negative index of refraction.
I will then underline the concept of electron viscosity in actual electron systems (rarely discussed in literature and not measured in experiments yet) in condensed matter and its consequences on the electromagnetic response. In particular I will discuss how optical spectroscopy can be used to probe the electron viscosity. Indeed finite viscosity has the effect to decrease the reflectivity of a metallic surface, and support the occurrence, in a half-infinite sample, of oscillations of the electromagnetic field intensity as a function of distance from the interface.
I will conclude with some comments on future perspectives and applications.