Mihailo Čubrović: Hydrodynamics of unstable systems: from the worldsheet to Fermi surfaces

We will discuss two examples of hydrodynamic instabilities and how they might be cured, in two very different examples from string theory in the broadest sense. The first configuration is the dragging open string in AdS black hole background, dual to a heavy quark in super-Yang-Mills plasma. The quark motion shows a single pole skipping point, without a tower of points characteristic of most other systems. The pole-skipping point is the only point in the whole energy-momentum plane where the quark oscillations do not grow, leading to a radiation instability.

The second example is the electron star, the holographic dual to a large-N Fermi liquid with a peculiar dispersion relation, where a pole develops in the upper half-plane in the transverse channel, again signaling an instability. We then discuss the implications for the holographic modeling of Fermi surfaces, and propose ways to construct stable holographic Fermi liquids.