Barrier With Nonzero Tail - Quantum Mechanics: Waves, Spin, and Tunneling Step by Step

This page starts tunneling with a deliberately small toy barrier, so the diagram can show a reflected part and a nonzero tail without solving a material problem. The exact 1/4 transmission is exact only inside the pinned model; a real tunneling setup would also depend on barrier shape, energy spread, detector efficiency, and measurement uncertainty.

Tunneling starts here as an exact finite model, not a material calculation. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

A barrier can leave a nonzero tail

This toy model gives a transmitted probability of 1/4. That is not a real material constant; it is the declared exact model.

T=\frac{1}{4}

The tail row is small but nonzero

The toy split shows reflected, transmitted, and total rows before any material claim is made.

\begin{array}{c|c|c}\text{part}&P&\text{claim}\\\text{reflected}&\frac{3}{4}&\text{larger}\\\text{transmitted}&\frac{1}{4}&\text{nonzero}\\\text{total}&1&\text{closed}\\\end{array}

The model is finite and exact

The diagram shows nonzero transmitted probability without solving a real barrier equation.

\text{toy amplitude model, not material data}