Dynamical breaking of electron-hole symmetry in nonequilibrium chiral quantum channels

We investigate the relaxation dynamics in a chiral one-dimensional quantum channel with finite-range interactions, driven out of equilibrium by the injection of high-energy electrons. While the distribution of high-energy electrons, after dissipation of some of their energy, has been examined previously [Phys. Rev. B 108, L081121 (2023)2469-995010.1103/PhysRevB.108.L081121], we study the distribution of charge carriers excited from the channel's Fermi sea during this process. Utilizing a detector to measure the energetic imprint in the Fermi sea downstream of the injection point, we discover an initial symmetry in the distribution of excited electrons and holes relative to the Fermi level. However, this symmetry breaks down with stronger interactions and increased propagation distances, attributed to terms of order four and beyond in the interaction. We interpret these results in terms of interference between states with different numbers of plasmons in the Fermi sea.