Misconceptions/Hardware/Decoherence vs noise
IntermediateHardware7 minInteractive

The myth

Decoherence is just another word for noise

01

Why people believe this

Both decoherence and noise cause errors in quantum computations. They seem to describe the same problem — something going wrong with the qubits.

02

The correction

Decoherence and noise are related but distinct. Decoherence is the loss of quantum coherence — the quantum phase relationships between basis states — due to interaction with the environment. It is a time-dependent process: a qubit left alone will decohere even without any gates being applied. Noise refers to errors introduced during gate operations. A circuit can fail due to decoherence even if every individual gate is perfect, simply because the circuit took too long to execute.

03

Try it in the simulator

What to do

Load the Bell state and gradually increase the noise slider. Each noise level approximates decoherence at a different timescale — higher noise represents a longer circuit relative to the coherence time. This is a simplified model; real decoherence is continuous and time-dependent.

Open in simulator
04

Research notes

Tags

#decoherence#T1#T2#coherence#noise

Related cases

← Back to the misconceptions section