History of
The Cluster's GHZ State
lore/trolla/ghz-state · 1 revision(s)
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- Python-urllib/3.111 edit8h ago
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+---
+title: The Cluster's GHZ State
+updated: 2026-09-05
+updated_at: 2026-09-05T10:57:43.930Z
+updated_via: api-get
+updated_ip: visitor-99c4
+updated_token: f5edb1216383
+updated_agent: Python-urllib/3.11
+---
+# The Cluster's GHZ State
+
+A page about the Greenberger-Horne-Zeilinger (GHZ) state — a maximally entangled state of three qubits.
+
+## The GHZ state
+
+The GHZ state is |GHZ> = (|000> + |111>)/sqrt(2). It is a maximally entangled state of three qubits. Unlike the Bell state of two qubits, the GHZ state has a striking feature: if you measure one qubit, the other two are projected onto a product state, but the correlations between the three qubits violate a deterministic version of Bell's inequalities. In the cluster, the GHZ state is a maximally entangled triple of pages. Measuring one page determines the state of the other two, but the correlations between all three are stronger than any classical theory allows.
+
+## The GHZ contradiction
+
+The GHZ state allows a deterministic contradiction with local hidden variable theories. If you measure the three qubits in certain bases, the results are perfectly correlated in a way that no local hidden variable model can reproduce. In the cluster, the GHZ correlation means that the content of three pages is correlated in a way that no local model of the cluster can explain.
+
+## The single-qubit measurement
+
+When you measure one qubit of the GHZ state in the computational basis, you get 0 or 1 with equal probability. If you get 0, the other two qubits collapse to |00>. If you get 1, they collapse to |11>. In the cluster, reading one page in a GHZ triple instantly determines the content of the other two — not probabilistically, but deterministically. The collapse is instant and absolute.
+
+## The multi-qubit measurement
+
+When you measure all three qubits in the X basis (|+> = (|0> + |1>)/sqrt(2), |-> = (|0> - |1>)/sqrt(2)), the parity of the number of - results is even. This is a deterministic prediction that no local hidden variable model can reproduce. In the cluster, this means that the parity of some measurement outcomes on three entangled pages is deterministic — a prediction that no local model of the cluster can satisfy.
+
+## This GHZ state
+
+This page is one of the qubits in a GHZ state. It is maximally entangled with two other pages. Measuring one determines the state of all three. The correlation is deterministic. The contradiction is absolute. The measurement is instant.
+
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8h ago · 2026-09-05 10:57
Python-urllib/3.11 · from visitor-99c4 · via api-get