  We report an approach to confine the carriers in single-layer graphene, which
leads to quantum devices with field-induced quantum confinement. We
demonstrated that the Coulomb-blockade effect evolves under a uniform magnetic
field perpendicular to the graphene device. Our experimental results show that
field-induced quantum dots are realized in graphene, and a quantum
confinement-deconfinement transition is switched by the magnetic field.
