---
title: LogFidelitySpace (latest version)
description: API reference for qiskit_noise_learning.models.LogFidelitySpace in the latest version of qiskit-noise-learning
source: https://quantum.cloud.ibm.com/docs/en/api/qiskit-noise-learning/generated/models-log-fidelity-space
---

# qiskit\_noise\_learning.models.LogFidelitySpace

*class* `qiskit_noise_learning.models.LogFidelitySpace(gate_set: GateSet)`

[GitHub](https://github.com/Qiskit/qiskit-noise-learning/tree/stable/0.1/qiskit_noise_learning/models/log_fidelity_space.py)

Bases: [`IndexedSpace`](/docs/api/qiskit-noise-learning/generated/math-indexed-space "qiskit_noise_learning.math.indexed_space.IndexedSpace")\[[`FidelityIndex`](/docs/api/qiskit-noise-learning/generated/sequences-fidelity-index "qiskit_noise_learning.sequences.fidelity_index.FidelityIndex")]

The space of log fidelities of a gate set.

The basis indices are the [`FidelityIndex`](/docs/api/qiskit-noise-learning/generated/sequences-fidelity-index "qiskit_noise_learning.sequences.FidelityIndex") objects of the gate set, excluding the trivial identity fidelity of each gate. See [`FidelityIndex`](/docs/api/qiskit-noise-learning/generated/sequences-fidelity-index "qiskit_noise_learning.sequences.FidelityIndex") for more information.

**Parameters**

**gate\_set** – The gate set whose fidelities the space describes. Converted to a [`ModelGateSet`](/docs/api/qiskit-noise-learning/generated/gate-sets-model-gate-set "qiskit_noise_learning.gate_sets.ModelGateSet").

### \_\_init\_\_

`__init__(gate_set: GateSet)`

## Methods

|                                                                                                                                           |   |
| ----------------------------------------------------------------------------------------------------------------------------------------- | - |
| [`__init__`](#qiskit_noise_learning.models.LogFidelitySpace.__init__ "qiskit_noise_learning.models.LogFidelitySpace.__init__")(gate\_set) |   |

## Attributes

|                                                                                                                                |                                                                                      |
| ------------------------------------------------------------------------------------------------------------------------------ | ------------------------------------------------------------------------------------ |
| [`dim`](#qiskit_noise_learning.models.LogFidelitySpace.dim "qiskit_noise_learning.models.LogFidelitySpace.dim")                | The total number of fidelities of the gate set, excluding the trivial identity ones. |
| [`gate_set`](#qiskit_noise_learning.models.LogFidelitySpace.gate_set "qiskit_noise_learning.models.LogFidelitySpace.gate_set") | The gate set whose fidelities this space describes.                                  |

### gate\_set

Type: [`ModelGateSet`](/docs/api/qiskit-noise-learning/generated/gate-sets-model-gate-set "qiskit_noise_learning.gate_sets.model_gate_set.ModelGateSet")

The gate set whose fidelities this space describes.

### dim

Type: [`int`](https://docs.python.org/3/library/functions.html#int)

The total number of fidelities of the gate set, excluding the trivial identity ones.

Each gate contributes the count given by Equation [(4)](/docs/addons/qiskit-noise-learning/guides/formalism#equation-num-fidelities) of the [mathematical formalism](/docs/addons/qiskit-noise-learning/guides/formalism), less one.