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QFI

qiskit.opflow.gradients.QFI(qfi_method='lin_comb_full')

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Bases: QFIBase

Deprecated: Compute the Quantum Fisher Information (QFI).

Computes the QFI given a pure, parameterized quantum state, where QFI is:

QFIkl=4Re[kψlψkψψψlψ].\mathrm{QFI}_{kl}= 4 \mathrm{Re}[\langle \partial_k \psi | \partial_l \psi \rangle − \langle\partial_k \psi | \psi \rangle \langle\psi | \partial_l \psi \rangle].
Deprecated since version 0.24.0

The class qiskit.opflow.gradients.qfi.QFI is deprecated as of qiskit-terra 0.24.0. It will be removed in the Qiskit 1.0 release. For code migration guidelines, visit https://qisk.it/opflow_migration(opens in a new tab).


Attributes

qfi_method

Returns CircuitQFI.

Returns

CircuitQFI.


Methods

convert

convert(operator, params=None)

Parameters

Returns

ListOp[ListOp] where the operator at position k,l corresponds to QFI_kl

Raises

ValueError(opens in a new tab) – If operator is not parameterized.

Return type

ListOp

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