▎ 摘　　要

Wave function scars refer to localized complex patterns of enhanced wave function probability distributions in a quantum system. Existing experimental studies of wave function scars concentrate nearly exclusively on nonrelativistic quantum systems. Here we present a combined experimental and theoretical study of a relativistic quantum cavity system realized by etching a graphene sheet. The conductance of the graphene cavity has been measured as a function of the back gate voltage (or the Fermi energy) and the magnetic field applied perpendicularly to the graphene sheet, and characteristic conductance contour patterns are observed at low temperatures. In particular, two types of high-conductance contour lines, i.e., straight and parabolic-like high-conductance contour lines, are found in the measurements. The theoretical calculations are performed within the framework of the tight-binding approach and Green's function formalism. Characteristic high-conductance contour features similar to those in the experiments are found in the calculations. Specifically, the equally spaced, parallel, straight high-conductance contour lines signify the persistence of relativistic quantum scars. The wave functions calculated at points selected along such a straight conductance contour line are found to be dominated by a chain of scars of high-probability distributions arranged as a necklace following the shape of the cavity, and the current density distributions calculated at these point are dominated by an overall vortex in the cavity. These characteristics are found to be insensitive to increasing magnetic field. However, the wave function probability distributions and the current density distributions calculated at points selected along a paraboliclike contour line show a clear dependence on increasing magnetic field, and the current density distributions at these points are characterized by the complex formation of several localized vortices in the cavity. Our work brings insight into quantum chaos in relativistic particle systems and should greatly stimulate experimental and theoretical efforts in this still emerging field.