**Maxime Dupont (U.C. Berkeley)**

Hydrodynamics in Quantum Magnets

(Séminaire https://zoom.us/j/95348880802?pwd=MHk5ZnVqVHlsZkJuVWhrOWIveDdlQT09 ID de réunion : 953 4888 0802 Code secret : 035303)

Some quantum many-body systems display emergent coarse-grained hydrodynamic behavior. One can make an analogy with the phenomenological derivation of classical fluid dynamics, based on the continuity equations of conserved quantities (such as mass, energy, or momentum). Depending on the intrinsic quantum conservation laws of the system, one expects different kinds of fluid-like behaviors. Remarkably, a class of 1D quantum systems, known as integrable, possesses an infinite number of nontrivial conserved quantities. They can endow them with peculiar transport properties, especially at high temperatures.

In this talk, I will present to you how the different hydrodynamic regimes in 1D quantum magnets are classified [1]. I will also discuss a recent theoretical-experimental collaboration [2] observing with neutrons one of these regimes in a nearly-ideal antiferromagnetic spin-1/2 Heisenberg chain material (KCuF_3). We found that the spin dynamics belong to the Kardar-Parisi-Zhang universality class in 1+1 dimensions, confirming the recent theoretical conjecture.

[1] M. Dupont and J. E. Moore, Phys. Rev. B 101, 121106(R) (2020)

[2] A. Scheie, et al., arXiv:2009.13535