Dynamics of Chiral Fermions in Condensed Matter Systems

In condensed matters, such as 3D Dirac and Weyl semimetals, fermions with linear energy-momentum dispersion gain chirality (handedness). The chiral anomaly produces an imbalance between the densities of right- and left-handed fermions, leading to generation of electric current in parallel electric and magnetic fields. This is called the chiral magnetic effect. Coupling of circular polarized light to chiral fermions breaks the chiral symmetry, and can generate chirality-dependent photocurrent. In this article, we review dynamics of chiral fermions in condensed matter systems to explain the theory of chiral magnetic effect and describe experimental signatures of the chiral anomaly. We then summarize recent theoretical and experimental studies of topological phase transition involving Dirac and Weyl semimetals, and detections of chirality and chiral photocurrent in static and dynamically-driven Weyl states. We conclude with potential uses of chiral fermions in quantum information systems.