dual_from_marginal_probabilities

dual_from_marginal_probabilities(povm: BasePOVM, state: SparsePauliOp | DensityMatrix | Statevector, *, threshold: float = 1e-05) → BaseDual[source]

Return the dual frame of povm based on the marginal distribution of a supplied state.

This methods constructs a product dual frame where each local dual frame is parametrized with the alpha-parameters set as the marginal outcome probabilities of the supplied state.

Parameters:

  • povm (BasePOVM) – the POVM for which we want to build a dual frame.

  • state (SparsePauliOp | DensityMatrix | Statevector) – state from which to compute the marginal outcome probabilities.

  • threshold (float) – if an outcome probability is below the value of threshold, an offset equal to the threshold magnitude will be added to all probabilities in the same marginal distribution. This is designed to avoid having parameters of the frame super-operator set to zero, which would result in a ZeroDivisionError.

Raises:

NotImplementedError – if povm is not a povm_toolbox.quantum_info.product_povm.ProductPOVM instance.

Return type:

BaseDual