Equation 8 · Part 1 · Variational Evolution: How Quantum Computers Learn Their Answers
Symbol n
What this part means
n is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.
Its job in the formula
n is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.
Full expression→Symbol n→Article meaning
The passage around this formula
The result, now known throughout the field as the barren-plateau problem, is precise and unwelcome. For a parametrized circuit that forms an approximate unitary 2-design — informally, a circuit random enough, or deep enough, that its output statistics resemble those of a genuinely random unitary — the variance of the gradient of the cost function with respect to almost any parameter shrinks exponentially as the number of qubits n grows:
Learn the underlying idea
A variable is a named place for a value. Its letter is a local label: x can mean position in one formula and a data point in another.
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Sources cited in the article section
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