Quantum Gate Basics

A quantum gate is a reversible unitary operation on qubits - and gates are the alphabet Kronos writes its materials-chemistry and control circuits in.

The concept

A qubit state a|0>+b|1> is multiplied by a unitary matrix U (U-dagger U = I), rotating it without measuring. One-qubit gates move a point on the Bloch sphere; two-qubit gates like CNOT and CZ create entanglement. A small set such as {H, T, CNOT} is universal.

How Kronos uses it

Every quantum circuit Kronos runs - to model low-activation and plasma-facing materials, or to prototype control policies - is assembled from these gates. Understanding the gate set is understanding the cost of a fusion-materials calculation, because gate count and gate type set what hardware is required.

Honest note

These circuits run at research scale today; the fusion-scale advantage that uses millions of gates is expected around the mid-2030s.