Permutation

Generalized Permutation Matrix

A general permutation matrix can be expressed as the multiplication of a permutation matrix and a diagonal matrix. For instance, we can decompose a 4 \(\times\) 4 general permutation matrix as follows:

\[\begin{split}A = \left[ \begin{array}{cccc} & & a_0 & \\ a_1 & & & \\ & & & a_2 \\ & a_3 & & \end{array}\right] = \left[ \begin{array}{cccc} a_0 & & & \\ & a_1 & & \\ & & a_2 & \\ & & & a_3 \end{array}\right] \left[ \begin{array}{cccc} & & 1 & \\ 1 & & & \\ & & & 1 \\ & 1 & & \end{array}\right].\end{split}\]

cuStateVec API custatevecApplyPermutationMatrix applies a general permutation matrix like \(A\) to a state vector. The API may require external workspace for large matrices, and custatevecApplyPermutationMatrix_bufferSize provides the size of workspace.

Use case 

// check the size of external workspace
custatevecApplyPermutationMatrix_bufferSize(
    handle, svDataType, permutation, diagonals, diagonalsDataType, adjoint,
    nTargets, &extraWorkspaceSizeInBytes);

// allocate external workspace if necessary
void* extraWorkspace = nullptr;
if (extraWorkspaceSizeInBytes > 0)
    cudaMalloc(&extraWorkspace, extraWorkspaceSizeInBytes);

// perform permutation
custatevecApplyPermutationMatrix(
    handle, sv, svDataType, nIndexBits, permutation, diagonals,
    diagonalsDataType, adjoint, targets, nTargets, controls, nControls,
    extraWorkspace, extraWorkspaceSizeInBytes);

API reference

custatevecApplyPermutationMatrix_bufferSize

Warning

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custatevecApplyPermutationMatrix

Warning

doxygenfunction: Cannot find function “custatevecApplyPermutationMatrix” in doxygen xml output for project “cuStateVec” from directory: _xml

Swap of qubits

Note

This API is not available in this version.

Warning

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