Functions for calculating reduced density matrices, creating a new output Qureg. More...

Functions
Qureg	calcPartialTrace (Qureg qureg, int *traceOutQubits, int numTraceQubits)

Qureg	calcPartialTrace (Qureg qureg, std::vector< int > traceOutQubits)

Qureg	calcReducedDensityMatrix (Qureg qureg, int *retainQubits, int numRetainQubits)

Qureg	calcReducedDensityMatrix (Qureg qureg, std::vector< int > retainQubits)

Detailed Description

Functions for calculating reduced density matrices, creating a new output Qureg.

Function Documentation

◆ calcPartialTrace() [1/2]

Qureg calcPartialTrace	(	Qureg	qureg,
		int *	traceOutQubits,
		int	numTraceQubits )

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!

Definition at line 373 of file calculations.cpp.

                                                                             {
    validate_quregFields(qureg, __func__);
    validate_quregIsDensityMatrix(qureg, __func__);
    validate_targets(qureg, traceOutQubits, numTraceQubits, __func__);
    validate_quregCanBeReduced(qureg, numTraceQubits, __func__);
 
    // attempt to create reduced Qureg with same deployments as input Qureg
    Qureg out = validateAndCreateCustomQureg(
        qureg.numQubits - numTraceQubits, 
        qureg.isDensityMatrix,  qureg.isDistributed, 
        qureg.isGpuAccelerated, qureg.isMultithreaded, __func__);
 
    // set it to reduced density matrix
    auto targets = util_getVector(traceOutQubits, numTraceQubits);
    localiser_densmatr_partialTrace(qureg, out, targets);
 
    return out;
}

Referenced by calcPartialTrace(), calcReducedDensityMatrix(), and TEST_CASE().

◆ calcPartialTrace() [2/2]

Qureg calcPartialTrace	(	Qureg	qureg,
		std::vector< int >	traceOutQubits )

Warning: This function has not yet been unit tested and may contain bugs. Please use with caution!

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!

Remarks: This function is only available in C++.

Definition at line 440 of file calculations.cpp.

                                                                {
    return calcPartialTrace(qureg, traceOutQubits.data(), traceOutQubits.size());
}

◆ calcReducedDensityMatrix() [1/2]

Qureg calcReducedDensityMatrix	(	Qureg	qureg,
		int *	retainQubits,
		int	numRetainQubits )

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!

Definition at line 393 of file calculations.cpp.

                                                                                    {
    validate_quregFields(qureg, __func__);
    validate_quregIsDensityMatrix(qureg, __func__);
    validate_targets(qureg, retainQubits, numRetainQubits, __func__);
    validate_quregCanBeReduced(qureg, qureg.numQubits - numRetainQubits, __func__);
 
    auto traceQubits = util_getNonTargetedQubits(retainQubits, numRetainQubits, qureg.numQubits);
 
    // harmlessly re-validates
    return calcPartialTrace(qureg, traceQubits.data(), traceQubits.size());
}

Referenced by calcReducedDensityMatrix(), and TEST_CASE().

◆ calcReducedDensityMatrix() [2/2]

Qureg calcReducedDensityMatrix	(	Qureg	qureg,
		std::vector< int >	retainQubits )

Warning: This function has not yet been unit tested and may contain bugs. Please use with caution!

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!

Remarks: This function is only available in C++.

Definition at line 445 of file calculations.cpp.

                                                                      {
    return calcReducedDensityMatrix(qureg, retainQubits.data(), retainQubits.size());
}