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Noise models

A noise model describes how a QEC campaign’s circuits are corrupted. A campaign references one by name in its noise.model; the model resolves to a built-in or a project noise/*.noise.yaml file. Files are the source of truth — the library GUI reads them and writes copies, it never edits in place.

The library

Open Experiments → Noise models. The dialog lists built-in and project models; select one to see its description, citation, generator-argument coefficients, and YAML. Two actions:

Duplicate to edit — writes an editable noise/<name>.noise.yaml carrying the source model’s channels under a new name, and opens it. From there it’s yours to change.
Compare with — diffs two models’ generator-argument coefficients, showing only the channels that differ.

The `*.noise.yaml` schema

schema: 1
name: my-model
description: One sentence on what this model represents.
citation: optional provenance
generator_args:                     # or `null` for an entry-only model
  after_clifford_depolarization: 1
  before_round_data_depolarization: 1
  before_measure_flip_probability: 1
  after_reset_flip_probability: 1

generator_args are coefficients over the swept parameter p: at physical error rate p, each channel is applied at coefficient × p. A model lists only the channels it uses; omit the rest. The four channels map directly onto Stim’s Circuit.generated noise arguments.

Built-in models

Name	Shape
`uniform_depolarizing`	Every channel at `p` — the textbook baseline.
`SI1000`	Superconducting-inspired: measurement 5p, reset 2p, gates p, idling p/10. A generator-argument approximation of the full model.
`measurement_heavy`	Measurement flip at 10p, gate depolarization at p — readout-limited regimes.
`biased_z`	Z-biased (dephasing-dominated). Entry-only.

Entry-only models

Some noise can’t be expressed through Stim’s uniform generator arguments — Pauli bias, for instance. Such a model sets generator_args: null. It can only be used from an entry: campaign source, where nuclei_circuits(noise) receives {p} (plus any custom keys you add) and applies the structure itself.