This is a simulation of a quantum free particle. The quantum free particle is composed of momentum states corresponding to different wavelengths and energies. The amplitude of each momentum state is plotted on the right, along with the amplitude of the overall wave function, which is a linear combination of all momentum states. You can alter the momentum state coefficients and observe how the wave function and probability density plot change. You can also evolve the wave function over time and collapse the wave function probabilistically.