qml.workflow.get_best_diff_method

get_best_diff_method(qnode)

Returns a function that computes the ‘best’ differentiation method for a particular QNode.

This method prioritizes differentiation methods in the following order (SPSA-based and Hadamard-based gradients are not included here):

• "device"

• "backprop"

• "parameter-shift"

Note

The first differentiation method that is supported (from top to bottom) will be returned. The order is designed to maximize efficiency, generality, and stability.

See also

For a detailed comparison of the backpropagation and parameter-shift methods, refer to the quantum gradients with backpropagation example.

Parameters

qnode (QNode) – the qnode to get the ‘best’ differentiation method for.

Returns

the gradient transform.

Return type

str

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