What Is Computation?

Before we touch a single qubit, it helps to be precise about what a computation actually is. At its core, a computation is the rule-based transformation of information: you start with some input, apply a fixed set of rules step by step, and end with an output.

That definition is deliberately broad. Adding two numbers, sorting a list, rendering this page, and factoring a large integer are all computations — they differ only in the rules applied and how many steps they take. A model of computation makes "information" and "rules" concrete: it says how information is stored (for classical computers, in bits) and which elementary operations (gates) are allowed.

Quantum computing is a different model. It stores information in qubits and allows operations that have no classical counterpart — superposition and interference. Everything in this track builds toward that model, but the questions stay the same: what can we represent, what operations are allowed, and how many steps does a problem take?

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