Quantum Harmonic Oscillator — Coherent States & Superposition

Coherent states |α⟩ are displaced Gaussian wavepackets that evolve classically, following a circular orbit in phase space. Schrödinger cat states — superpositions of two coherent states — produce quantum interference fringes in the Wigner function, a signature with no classical analog.

1.5
π
coherent
Wigner function W(x,p) — blue: negative (quantum) regions, red/yellow: positive regions