Non-linear chiral magnetic waves

Abstract

The chiral magnetic wave (CMW) is a macroscopic quantum phenomenon that arises due to the mixing of the electric and chiral charge oscillations induced by the chiral anomaly. In this study we report the first quantum simulation (on classical hardware) of the real-time dynamics of CMWs in Schwinger model. Our quench protocol is the following: at $t=0$ we suddenly place an electric dipole at the middle of our lattice. Due to chiral anomaly, this dipole excites the CMW that propagates towards the edges of the lattice. In Schwinger model tuned to the conformal critical point (at $\theta = \pi$, $m/g \simeq 0.2$), we find a gapless linear CMW that propagates with the speed of light. For massless Schwinger model ($\theta =0, m=0$), we find a gapped linear CMW, in accord with previous analytical analyses. For massive Schwinger model (that is dual to strongly interacting bosonic theory), we enter the new regime of nonlinear CMWs, where we find a surprise. Specifically, for $m/g > 1$, the frequency of electric charge oscillations becomes much smaller than the frequency of the oscillations of the chiral charge. For $m/g =4$, we find a solution corresponding to a nearly static electric dipole with fast oscillations of the chiral charge confined within. We call this solution a "thumper" and study its properties in detail.