47 lines
1.4 KiB
Plaintext
47 lines
1.4 KiB
Plaintext
---
|
||
title: QFIBase
|
||
description: API reference for qiskit.opflow.gradients.QFIBase
|
||
in_page_toc_min_heading_level: 1
|
||
python_api_type: class
|
||
python_api_name: qiskit.opflow.gradients.QFIBase
|
||
---
|
||
|
||
# QFIBase
|
||
|
||
<Class id="qiskit.opflow.gradients.QFIBase" isDedicatedPage={true} github="https://github.com/qiskit/qiskit/tree/stable/0.20/qiskit/opflow/gradients/qfi_base.py" signature="QFIBase(qfi_method='lin_comb_full')" modifiers="class">
|
||
Bases: `qiskit.opflow.gradients.derivative_base.DerivativeBase`
|
||
|
||
Base class for Quantum Fisher Information (QFI).
|
||
|
||
Compute the Quantum Fisher Information (QFI) given a pure, parameterized quantum state.
|
||
|
||
The QFI is:
|
||
|
||
> \[QFI]kl= Re\[〈∂kψ|∂lψ〉−〈∂kψ|ψ〉〈ψ|∂lψ〉] \* 4.
|
||
|
||
**Parameters**
|
||
|
||
**qfi\_method** (`Union`\[`str`, `CircuitQFI`]) – The method used to compute the state/probability gradient. Can be either a [`CircuitQFI`](qiskit.opflow.gradients.CircuitQFI "qiskit.opflow.gradients.CircuitQFI") instance or one of the following pre-defined strings `'lin_comb_full'`, `` 'overlap_diag'` `` or `` 'overlap_block_diag'` ``.
|
||
|
||
**Raises**
|
||
|
||
**ValueError** – if `qfi_method` is neither a `CircuitQFI` object nor one of the predefined strings.
|
||
|
||
## Attributes
|
||
|
||
### qfi\_method
|
||
|
||
<Attribute id="qiskit.opflow.gradients.QFIBase.qfi_method">
|
||
Returns `CircuitQFI`.
|
||
|
||
**Return type**
|
||
|
||
`CircuitQFI`
|
||
|
||
**Returns**
|
||
|
||
`CircuitQFI`.
|
||
</Attribute>
|
||
</Class>
|
||
|