BB84 Quantum Key Distribution Protocol

Alice sends qubits in random bases. Bob measures. Eve intercepts. QBER > 11% reveals eavesdropping.

Key bits: 0
QBER: 0%
Status: Ready
BB84 Bases:
Z-basis: |0⟩/|1⟩ (↑/↓)
X-basis: |+⟩/|-⟩ (↗/↘)
Sifting: keep bits where Alice and Bob chose same basis (~50%)
Eve detection: wrong-basis intercept introduces 25% error per bit
Sifted Key:
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