Symmetry protected long-lived excitations and tomographic dynamics in 2D electron fluids

We will discuss the peculiar collective behavior in two-dimensional Fermi gases arising from head-on carrier-carrier collisions. These collisions dominate at cold temperatures, T << T_F, due to the combined effects of Pauli blocking and momentum conservation. Odd-parity harmonics are protected from these collisions and hence have anomalously long lifetimes. They instead slowly relax via small angle scattering which leads to a strange "superdiffusive" behavior. These long-lived modes give rise to a "tomographic" transport regime dominated by fermionic jets with an unusual hierarchy of time scales and scale-dependent transport coefficients with nontrivial fractional scaling dimensions. We will also discuss proposals for experimental realizations and implications for ongoing studies of electron hydrodynamics.

References:

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P. J. Ledwith, H. Guo, and L. Levitov, Annals of Physics 411, 167913 (2019).

P. J. Ledwith, H. Guo, and L. Levitov, (2019), arXiv:1708.01915.

L. H. Kendrick, P. J. Ledwith, A. Shytov, and L. Levitov, (2018), arXiv:1810.07588.