The paper discusses the Klein paradox, a counterintuitive phenomenon in quantum electrodynamics (QED) where relativistic particles can penetrate high and wide potential barriers without significant resistance. This paradox, which has never been directly observed experimentally, is demonstrated to be testable in condensed matter systems using graphene. Due to the chiral nature of its quasiparticles, graphene exhibits highly anisotropic quantum tunneling, making it an ideal material for studying the Klein paradox. In single-layer graphene, the quasiparticles are massless Dirac fermions, allowing for perfect transmission through potential barriers, especially at normal incidence angles. This behavior is attributed to the conservation of pseudospin, which ensures that electrons moving in one direction cannot transform into holes moving in the opposite direction. In contrast, bilayer graphene, where quasiparticles are massive chiral fermions, shows perfect reflection at normal incidence angles, even for low barriers. The authors compare these findings with the tunneling of non-chiral particles, emphasizing that the Klein-like behavior in graphene is unique to its chiral nature. They suggest that these findings could have implications for understanding transport properties in graphene, such as the suppression of Anderson localization due to the transparency of potential barriers. The paper also outlines experimental setups to test these phenomena, including the use of local gates and collimators to create and measure potential barriers in graphene devices.The paper discusses the Klein paradox, a counterintuitive phenomenon in quantum electrodynamics (QED) where relativistic particles can penetrate high and wide potential barriers without significant resistance. This paradox, which has never been directly observed experimentally, is demonstrated to be testable in condensed matter systems using graphene. Due to the chiral nature of its quasiparticles, graphene exhibits highly anisotropic quantum tunneling, making it an ideal material for studying the Klein paradox. In single-layer graphene, the quasiparticles are massless Dirac fermions, allowing for perfect transmission through potential barriers, especially at normal incidence angles. This behavior is attributed to the conservation of pseudospin, which ensures that electrons moving in one direction cannot transform into holes moving in the opposite direction. In contrast, bilayer graphene, where quasiparticles are massive chiral fermions, shows perfect reflection at normal incidence angles, even for low barriers. The authors compare these findings with the tunneling of non-chiral particles, emphasizing that the Klein-like behavior in graphene is unique to its chiral nature. They suggest that these findings could have implications for understanding transport properties in graphene, such as the suppression of Anderson localization due to the transparency of potential barriers. The paper also outlines experimental setups to test these phenomena, including the use of local gates and collimators to create and measure potential barriers in graphene devices.