Quantized Transient Nonlinear Rabi Frequency Response in Weyl Semimetals

Abstract

The three-dimensional (3D) analog of graphene is called Weyl semimetal, where the energy of the excitations is linear function of momentum. This is a peculiar topological phase of 3D materials, which are described by the existence of a set of linear-dispersive band-touching points called Weyl nodes, which have robustness against small perturbations and disorder. We showed that these systems are best characterized using the phenomenon of quantum anomalous Rabi oscillation that occurs far from resonance and is unique to these Dirac fermionic systems. These oscillations are absent in conventional two-level systems. For a single photon or even a vacuum, the same phenomenon is also seen in a Weyl semimetal i.e. the phenomenon of quantum anomalous Rabi oscillation is not a spurious outcome of poor approximations. The Bloch equations unambiguously demonstrate the presence of not only quantum anomalous Rabi oscillations in these systems but also their massless character. Here we study thequantum anomalous Rabi oscillationsin the Weyl semimetal and point out salient differences between the analogous phenomenon in graphene.