QCQI – Chapter 12: Quantum Cryptography & Communication

Course Slides (MSU)

Learning Objectives¶

• No-cloning & disturbance $\Rightarrow$ QKD.

• BB84 pipeline: sifting $\to$ QBER $\to$ IR $\to$ PA.

• B92, E91 intuition; practical attacks & decoys.

Security Intuition¶

No-cloning; incompatible bases; disturbance reveals Eve.

Eureka! QBER is the security dial.

BB84 in One Slide¶

Random bases; sift; estimate QBER; IR; PA.

Intercept-resend $\Rightarrow$ $\sim$25% QBER on sifted bits.

Beyond BB84¶

B92 (two-state, inconclusive), E91 (Bell-violation bound), decoy states vs. PNS.

Eureka! Nonorthogonality and nonlocality both fuel security.

Schematics¶

Hands-on Notebook¶

Companion notebook (multi-backend):L16_QCQI_Ch12_QKD_and_Quantum_Cryptography

Set backend in the first cell to cirq, pennylane, braket, pyquil, or qiskit.

Mini-Lab¶

• QBER vs. eavesdrop fraction.

• Toy IR+PA net key length.

• E91 CHSH statistic.