Feynman Path Integral
Quantum amplitude as a coherent sum over interfering classical paths
Setup
Potential type
Free particle
Harmonic oscillator
Potential barrier
Double well
Start x_A
-2.0
End x_B
2.0
ℏ (effective)
1.0
Paths shown
40
Time slices
8
Animate
New Paths
|K(B,A)|² = —
Paths: 0
K(B,A) = ∫ 𝒟x exp(iS[x]/ℏ)
Each path contributes a phasor e^{iS/ℏ}. Classical path has stationary phase → constructive interference. Off-classical paths cancel.
Color = phase angle. Bright = high amplitude. Small ℏ → classical limit.