iqm.benchmarks.compressive_gst.mgst.additional_fns.Kraus_rep

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iqm.benchmarks.compressive_gst.mgst.additional_fns.Kraus_rep#

iqm.benchmarks.compressive_gst.mgst.additional_fns.Kraus_rep(X: ndarray, d: int, pdim: int, rK: int) → ndarray#

Compute the Kraus representations for all gates in the gate set.

Parameters:

  • X (ndarray) – Current gate estimate

  • d (int) – Number of gates

  • pdim (int) – Physical dimension

  • rK (int) – Target Kraus rank

Returns:

Each subarray along the first axis contains a set of Kraus operators.

The second axis enumerates Kraus operators for a gate specified by the first axis.

Return type:

K

Notes

The Kraus representation is obtained from a singular value decomposition of the Choi matrix. If parameter rK is smaller than the true rank of the Choi matrix, a rank rK approximation is used. Approximations are only CPT in the special case where the original gate was already of rank <= rK.

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