Symbol Lambda
Lambda is part of the quantity the equation computes from the expression on the right.
Read this term in its guide →Published equation contexts
Why this formula appears here
so that each increase of the code distance by two multiplies the protection by a factor conventionally written . Below threshold means > 1 . Above threshold, adding qubits makes the logical qubit worse, because each additional physical qubit contributes more error than the larger code removes. This is the sense in which qubit count is not merely an incomplete figure of merit but can be an actively misleading one.
Read the representative guide
Symbol P_L
is one of the signed contributions combined to compute the quantity on the left.
Read this term in its guide →Symbol d
d is one of the signed contributions combined to compute the quantity on the left.
Read this term in its guide →Denominator: P_L(d+2)
The complete quantity below the fraction bar; it must be nonzero for this division.
Read this term in its guide →How to interpret it
With a fixed numerator, increasing a nonzero denominator reduces the fraction. Read it with the definitions, units, and assumptions supplied by the article.
Research cited beside this formula
Published contexts (1)
A symbol can carry a different meaning in another article. Each occurrence keeps its own guide and term definitions.
Equation 28 · Quantum Information
Error Correction Is the Whole Problem in Quantum Computing
This equation states an equality: the expressions on both sides have the same value under the article’s assumptions.
so that each increase of the code distance by two multiplies the protection by a factor conventionally written . Below threshold means > 1 . Above threshold, adding qubits makes the logical qubit worse, because each additional physical qubit contributes more error than the larger code removes. This is the sense in which qubit count is not merely an incomplete figure of merit but can be an actively misleading one.
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