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QFIBase
class qiskit.opflow.gradients.QFIBase(qfi_method='lin_comb_full')
Bases: DerivativeBase
Deprecated: 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.
Deprecated since version 0.24.0
The class qiskit.opflow.gradients.qfi_base.QFIBase
is deprecated as of qiskit-terra 0.24.0. It will be removed no earlier than 3 months after the release date. For code migration guidelines, visit https://qisk.it/opflow_migration.
Parameters
qfi_method (str |CircuitQFI) – The method used to compute the state/probability gradient. Can be either a 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
Returns CircuitQFI
.
Returns
CircuitQFI
.
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