Quantum Harmonic Oscillator is an educational app that allows users to visualize the eigenstates of the three-dimensional quantum harmonic oscillator. Developed by Voladd, this app is available for free on the Android platform.

Quantum Harmonic Oscillator is a quantum mechanical system for which an exact, analytic solution is known. It is a useful tool because any arbitrary potential can be approximated by a harmonic potential in the vicinity of the equilibrium point. The app describes the wave-like behavior of a particle confined to a harmonic well through wave functions of the quantum harmonic oscillator. It determines the probability of finding the particle in a particular space region.

The app uses OpenGL to draw the cross-section surfaces of the square of the wave function, using the Marching Cubes algorithm. Additionally, it employs the spherical coordinate basis. Users can select the eigenstate by specifying the quantum numbers k, l, and m, or by picking a random one. The discretization step size is adjustable and users can choose the total probability to find the particle inside the drawn orbital surface. The surface can be zoomed and rotated with the fingers.