Function calcReducedDensityMatrix

quest/src/api/calculations.cpp:393–403

Qureg calcReducedDensityMatrix(Qureg qureg, int* retainQubits, int numRetainQubits) {
    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());
}


} // end de-name mangler