PauliStrSum

Functions for pre- or post-multiplying weighted sums of Pauli tensors upon a density matrix. More...

Functions
void	leftapplyPauliStrSum (Qureg qureg, PauliStrSum sum, Qureg workspace)
void	rightapplyPauliStrSum (Qureg qureg, PauliStrSum sum, Qureg workspace)

Detailed Description

Functions for pre- or post-multiplying weighted sums of Pauli tensors upon a density matrix.

Function Documentation

leftapplyPauliStrSum()

void leftapplyPauliStrSum	(	Qureg	qureg,
		PauliStrSum	sum,
		Qureg	workspace )

Note

Documentation for this function or struct is under construction!

Attention

This function's input validation has not yet been unit tested, so erroneous usage may produce unexpected output. Please use with caution!

See also

leftapplyCompMatr1()

Definition at line 649 of file multiplication.cpp.

                                                                         {
    validate_quregFields(qureg, __func__);
    validate_quregFields(workspace, __func__);
    validate_quregCanBeWorkspace(qureg, workspace, __func__);
    validate_pauliStrSumFields(sum, __func__);
    validate_pauliStrSumTargets(sum, qureg, __func__);
 
    // clone qureg to workspace, set qureg to blank
    localiser_statevec_setQuregToClone(workspace, qureg);
    localiser_statevec_initUniformState(qureg, 0);
 
    // left-multiply each term in-turn, mixing into output qureg, then undo using idempotency
    for (qindex i=0; i<sum.numTerms; i++) {
        localiser_statevec_anyCtrlPauliTensor(workspace, none, none, sum.strings[i]);
        localiser_statevec_setQuregToWeightedSum(qureg, {1, sum.coeffs[i]}, {qureg, workspace});
        localiser_statevec_anyCtrlPauliTensor(workspace, none, none, sum.strings[i]);
    }
 
    // workspace -> qureg, and qureg -> sum * qureg
}

Referenced by TEST_CASE().

rightapplyPauliStrSum()

void rightapplyPauliStrSum	(	Qureg	qureg,
		PauliStrSum	sum,
		Qureg	workspace )

Note

Documentation for this function or struct is under construction!

Attention

This function's input validation has not yet been unit tested, so erroneous usage may produce unexpected output. Please use with caution!

See also

leftapplyCompMatr1()

Definition at line 670 of file multiplication.cpp.

                                                                          {
    validate_quregFields(qureg, __func__);
    validate_quregFields(workspace, __func__);
    validate_quregIsDensityMatrix(qureg, __func__);
    validate_quregCanBeWorkspace(qureg, workspace, __func__);
    validate_pauliStrSumFields(sum, __func__);
    validate_pauliStrSumTargets(sum, qureg, __func__);
 
    // clone qureg to workspace, set qureg to blank
    localiser_statevec_setQuregToClone(workspace, qureg);
    localiser_statevec_initUniformState(qureg, 0);
 
    // post-multiply each term in-turn, mixing into output qureg, then undo using idempotency
    for (qindex i=0; i<sum.numTerms; i++) {
        PauliStr str =  paulis_getShiftedPauliStr(sum.strings[i], qureg.numQubits);
        qcomp factor = paulis_getSignOfPauliStrConj(str); // undoes transpose
 
        localiser_statevec_anyCtrlPauliTensor(workspace, none, none, str, factor);
        localiser_statevec_setQuregToWeightedSum(qureg, {1, sum.coeffs[i]}, {qureg, workspace});
        localiser_statevec_anyCtrlPauliTensor(workspace, none, none, str, factor);
    }
 
    // workspace -> qureg, and qureg -> sum * qureg
}

Referenced by TEST_CASE().