Symbol psi
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for a system in state | measured in a basis containing |a . Every interpretation discussed here reproduces this rule for every experiment that has actually been performed. That includes Bell tests. John Bell showed in 1964 that any theory obeying two assumptions — that a measurement’s outcome depends only on a hidden variable carried by the particle and on the local setting of its own detector, not on the distant detector’s setting — predicts correlations between two separated measurements that are bounded above by a fixed value [ 1 ] . Quantum mechanics predicts correlations that exceed that bound for entangled pairs. This is a fact, not an interpretation: it was measured,…
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Equation 2 · Physics
Comparing the Main Approaches to Quantum Foundations and Measurement
This mathematical expression combines the displayed quantities; its precise role follows from the surrounding article text.
for a system in state | measured in a basis containing |a . Every interpretation discussed here reproduces this rule for every experiment that has actually been performed. That includes Bell tests. John Bell showed in 1964 that any theory obeying two assumptions — that a measurement’s outcome depends only on a hidden variable carried by the particle and on the local setting of its own detector, not on the distant detector’s setting — predicts correlations between two separated measurements that are bounded above by a fixed value [ 1 ] . Quantum mechanics predicts correlations that exceed that bound for entangled pairs. This is a fact, not an interpretation: it was measured,…
Equation guide → · Article →Equation 2 · Quantum Information
Error Correction Is the Whole Problem in Quantum Computing
This mathematical expression combines the displayed quantities; its precise role follows from the surrounding article text.
cannot exist for all | , because unitarity preserves inner products and the required map does not. Wootters and Zurek established the point in 1982, in a paper whose title remains the cleanest statement of it [ 1 ] . There is no backup copy, no parity check computed by reading the data, no majority vote over three inspected replicas.
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