mirror of https://github.com/Qiskit/qiskit.git
25 lines
1.3 KiB
YAML
25 lines
1.3 KiB
YAML
---
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features:
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A new optimizer class, :class:`~qiskit.algorithms.optimizers.QNSPSA`,
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has been added to the :mod:`qiskit.algorithms.optimizers` module. This
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class implements the
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`Quantum Natural SPSA (QN-SPSA) <https://arxiv.org/abs/2103.09232>`__
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algorithm, a generalization of the 2-SPSA algorithm, and estimates the
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Quantum Fisher Information Matrix instead of the Hessian to obtain a
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stochastic estimate of the Quantum Natural Gradient. For examples on
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how to use this new optimizer refer to the
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:class:`~qiskit.algorithms.optimizers.QNSPSA` class documentation.
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A new kwarg, ``second_order``, has been added to the constructor
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of the :class:`~qiskit.algorithms.optimizers.SPSA` class in the
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:mod:`qiskit.algorithms.optimizers` module. When set to ``True`` this
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enables using
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`second-order SPSA <https://ieeexplore.ieee.org/document/657661>`__.
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Second order SPSA, or 2-SPSA, is an extension of the ordinary SPSA algorithm that
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enables estimating the Hessian alongside the gradient, which is used
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to precondition the gradient before the parameter update step. As a
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second-order method, this tries to improve convergence of SPSA.
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For examples on how to use this option refer to the
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:class:`~qiskit.algorithms.optimizers.SPSA` class documentation.
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