Equation 1 · Part 3 · How Post-CMOS, Neuromorphic, Photonic, and Quantum AI Compute Actually Works
Symbol Sigma
What this part means
Sigma is one factor in the product that computes the quantity on the left.
Its job in the formula
Sigma is one factor in the product that computes the quantity on the left.
Full expression→Symbol Sigma→Article meaning
The passage around this formula
An MZI mesh built this way implements a unitary matrix: a transformation that preserves the total optical power passing through it. Most matrices a neural-network layer actually needs are not unitary. The standard fix is a singular value decomposition, writing the desired matrix M as . where U and V* are unitary matrices, each realized by its own MZI mesh, and Σ is a diagonal matrix of non-negative singular values, realized by a bank of tunable optical attenuators placed between the two meshes. Light entering the chip passes through the first mesh, has each of its modes independently attenuated by the corresponding singular value, then passes through the second mesh — end…
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 surrounding passage
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