# About Blaise Goutéraux

I am a theorist working at the interface between high energy theory and condensed matter.

Strongly-correlated quantum phases of nature, such as the high Tc superconductors, fall outside the realm of the quasiparticle theory developed by Landau, so-called Fermi liquids. They display unconventional transport properties (most famously, a resistivity linear in temperature, as well as others) which cannot be accounted for by quasiparticles and Boltzmann transport. On the other hand, strong interactions make it very difficult tackling these systems using conventional approaches, which are often based around perturbation theory in a small coupling.

The holographic principle (aka gauge/gravity duality or ads/cft) is one of the most important insights coming out of string theory in the twentieth century. It lets us ask fundamental questions about gravity and the emergence of spacetime, but also about strongly-correlated quantum phases of matter in general, by mapping the dynamics of some strongly-interacting quantum field theories to theories of gravity in anti de Sitter spacetimes. Anti de Sitter is a solution of Einstein's equations with a negative cosmological constant (in contrast to our Universe, which appears to be well-described by a positive, albeit very small, cosmological constant).

More generally, I am also interested in hydrodynamics and effective field theory approaches, in the presence of broken symmetries. These approaches rest on the assumption that at long distances and late times, collective behavior emerges as a result of the conservation of a few fundamental quantities, such as charge, energy or momentum. The low energy dynamics is captured by the conservation equations as well as by a number of constitutive relations for the conserved currents. These involve an expansion in small gradients (of time and space). At the end of the day, the dynamics depends on a small, finite set of transport coefficients, which can be computed efficiently in microscopic models. In these sense, hydrodynamics allows to describe the universal sector of strongly-coupled phases of matter.

These symmetry-based approaches naturally connect with gauge/gravity duality, since the symmetries of the problem can be encoded in the gravity dual. By perturbing away from thermal equilibrium, all the holographic transport coefficients can be efficiently computed. This is particularly useful once symmetries are weakly broken (eg weak breaking of translations by disorder) and in the presence of quasi-conserved quantities.

You can find more details on what I have been up to recently by browing my list of publications on arXiv, Inspire or Google Scholar.