Why the GHZ Test Is Better Than Bell’s Original Setup

Also read – Derivation of GHZ

1. Bell’s Test is Statistical — GHZ is Deterministic

  • Bell’s theorem relies on statistical inequalities (like CHSH) that require many repeated measurements to build up probabilities.
  • GHZ provides a logical contradiction with local realism in a single set of measurements—no inequalities, no statistics.

👉 GHZ doesn’t rely on experimental loopholes like sampling bias. It’s conceptually sharper.

2. GHZ Reveals Contradictions Without Statistics

  • Bell’s violations are statistical averages (e.g., CHSH up to 2√2 vs classical bound 2).
  • GHZ shows that even one round of measurement contradicts local hidden variable logic.

“You don’t need to trust probabilities—just logic.”

3. It Sharpens the Local Realism Argument

Bell’s theorem leaves room for local realists to argue that violations are statistical anomalies.
GHZ removes that ambiguity completely.

“Even in the best-case, one-shot measurement, your classical logic breaks.”

4. Experimental Simplicity (in Principle)

  • GHZ experiments are harder practically due to needing 3 entangled particles.
  • But you don’t need randomized measurement settings or statistical analysis.

Summary: Why GHZ > Bell (Conceptually)

Feature Bell (2 particles) GHZ (3+ particles)
Relies on statistics? ✅ Yes ❌ No
Needs inequality formulation? ✅ Yes (e.g. CHSH) ❌ No
Logical contradiction? ❌ Not directly ✅ Yes
Requires repeated trials? ✅ Yes ❌ No (in theory)
Conceptual clarity Moderate High – exposes realism flaws