The phenomenon of scarring in single-particle wavefunctions represents one of the most striking signatures of quantum chaos. Due to quantum interference, the probability density of a quantum state can localize along short, unstable periodic orbits of the underlying classical system, imprinting them as quantum scars. While classical-wave analogues of the Heller-type scarring have long been reported, direct evidence in genuine quantum systems emerged only recently through scanning tunneling microscopy of graphene quantum dots. These systems now provide platforms to visualize diverse scar classes: quasi-scars induced by trigonal warping in bilayer graphene, and variational scars arising from approximate symmetries that, under local perturbations, select specific scarred states via the variational principle. Such scars should be observable in tunneling or transport measurements. Graphene devices also enable studies of antiscarring, where probability density is suppressed along classical orbits. Whereas scars can enhance conductance, antiscarring may yield longer-lived resonances. Together, these developments establish a foundation for scartronics -- harnessing quantum scarring to control electronic behavior in two-dimensional nanostructures.
*This project was also supported by the NSF (Grant No. 2403491). Moreover, A.M.G. thanks the Studien-stiftung des Deutschen Volkes PhD Fellowship and the Harvard Quantum Initiative for financial support., and J.K.-R. thanks the Oskar Huttunen Foundation for the financial support.
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