This Demonstration considers a three-dimensional cubic box with infinite potential walls in a degenerate stationary state with a constant phase shift. A free particle is contained between impenetrable and perfectly reflecting walls, separated by a distance . A system with three degrees of freedom assigned by a superposition of three stationary eigenfunctions that has commensurate energy eigenvalues and with a relative constant phase shift can exhibit chaotic motion in the associated de Broglie–Bohm picture, provided that the constant phase is not zero or an integer multiple of . The origin of the motion lies in the relative phase of the total wavefunction, which has no analog in classical particle mechanics. The dynamic structure is quite complex. Some of the curves are closed and periodic, while others are quasi-periodic. In the region of nodal points of the wavefunction the trajectories apparently become chaotic. The parameters have to be chosen carefully, because of the singularities of the velocities and the large oscillations that can lead to very unstable trajectories. Further investigation to capture the full dynamics of the system is necessary. The graphics show three-dimensional contour plots of the squared wavefunction and two initially neighboring trajectories. Black points mark the actual positions of the two quantum particles.