Abstract
We study the excitation of a one-electron quantum cyclotron by gravitational waves. The electron in such as a penning trap is prepared to be at the lowest Landau level, which has an infinite degeneracy parameterized by the spread of the wave function in position space. We find that the excitation rate from the ground state to the first excited state is enhanced by the size of the electron wave function: an electron with a larger wave function feels gravitational waves more. As a consequence, we derive a good sensitivity to gravitational waves at a macroscopic one-electron quantum cyclotron.