▎ 摘　　要

Massless Dirac particles cannot be confined by an electrostatic potential. This is a problem for making graphene quantum dots but confinement can be achieved with a magnetic field and here general conditions for confined and deconfined states are derived. There is a class of potentials for which the character of the state can be controlled at will. Then a confinement deconfinement transition occurs which allows the Klein paradox to be probed experimentally in graphene dots. A dot design suitable for this experiment is presented.