QFI

class QFI(qgt, options=None)

Bases: ABC

Computes the Quantum Fisher Information (QFI) given a pure, parameterized quantum state. QFI is defined as:

\[\mathrm{QFI}_{ij}= 4 \mathrm{Re}[\langle \partial_i \psi | \partial_j \psi \rangle - \langle\partial_i \psi | \psi \rangle \langle\psi | \partial_j \psi \rangle].\]

Parameters

• qgt (BaseQGT) – The quantum geometric tensor used to compute the QFI.

• options (Options | None) – Backend runtime options used for circuit execution. The order of priority is: options in run method > QFI’s default options > primitive’s default setting. Higher priority setting overrides lower priority setting.

Methods

run	Run the job of the QFIs on the given circuits.
update_default_options	Update the gradient's default options setting.

Attributes

options

Return the union of QGT’s options setting and QFI’s default options, where, if the same field is set in both, the QFI’s default options override the QGT’s default setting.

Returns

The QFI default + QGT options.