Drag the coloured handles on the Alice / Bob circles to rotate their measurement axes. Hover a dot on the correlation plot to read it.
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Controls
Entangled pairs: Bell / CHSH test
Pause
Send 1 pair
Reset counts
Preset
Optimal CHSH settings
Aligned axes (no violation)
Classical hidden variable
Noisy channel (V = 70%)
Eavesdropper on the line
Measurement axes
Alice a0
Alice a1
Bob b0
Bob b1
Source and channel
Source
Quantum singlet
Local hidden variable
Visibility V
Pairs / s
Eavesdropper
Live readout
pairs
0
|S| measured
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|S| theory
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classical max
2.000
E(a0,b0)
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E(a0,b1)
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E(a1,b0)
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E(a1,b1)
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Bob + | a0
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Bob + | a1
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Bob's "+" rate stays at 50% whatever Alice chooses (no-signalling): entanglement correlates results, it cannot carry a message.
Running |S| estimate
Dashed lines: classical bound 2 and Tsirelson bound 2.83. CHSH: S = E(a0,b0) - E(a0,b1) + E(a1,b0) + E(a1,b1). Singlet: E = -V cos(angle between axes).