The Identity Gate

The identity gate does nothing on purpose - and that makes it Kronos's ruler for measuring how fast a real qubit forgets.

The concept

I = [[1,0],[0,1]] leaves a qubit unchanged. It is used as a timed no-op to keep circuit scheduling aligned while other qubits are driven.

How Kronos uses it

When Kronos benchmarks candidate quantum hardware for its materials workloads, strings of identity gates are the idle-error test: run many I's, measure how quickly the state decoheres, and you learn how deep a real materials circuit can go before noise wins.

Honest note

Decoherence is exactly why the useful fusion-chemistry advantage waits on error correction, expected around the mid-2030s.