CZ_NU.cpp

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/*
Created on Fri Jun 26 14:13:26 2020
Copyright 2020 Peter Rakyta, Ph.D.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

@author: Peter Rakyta, Ph.D.
*/
#include "CZ_NU.h"



using namespace std;


CZ_NU::CZ_NU() {

    // A string labeling the gate operation
    name = "CZ_NU";

    // number of qubits spanning the matrix of the gate
    qbit_num = -1;
    // the size of the matrix
    matrix_size = -1;
    // A string describing the type of the gate
    type = CZ_NU_OPERATION;
    // The number of free parameters
    parameter_num = 0;

    // The index of the qubit on which the gate acts (target_qbit >= 0)
    target_qbit = -1;

    // The index of the qubit which acts as a control qubit (control_qbit >= 0) in controlled gates
    control_qbit = -1;


}


CZ_NU::CZ_NU(int qbit_num_in,  int target_qbit_in, int control_qbit_in) {


    // A string labeling the gate operation
    name = "CZ_NU";
    // number of qubits spanning the matrix of the gate
    qbit_num = qbit_num_in;
    // the size of the matrix
    matrix_size = Power_of_2(qbit_num);
    // A string describing the type of the gate
    type = CZ_NU_OPERATION;
    // The number of free parameters
    parameter_num = 1;

    if (target_qbit_in >= qbit_num) {
        std::stringstream sstream;
        sstream << "The index of the target qubit is larger than the number of qubits" << std::endl;
        print(sstream, 0);                     
        throw sstream.str();
    }
    // The index of the qubit on which the gate acts (target_qbit >= 0)
    target_qbit = target_qbit_in;


    if (control_qbit_in >= qbit_num) {
        std::stringstream sstream;
        sstream << "The index of the control qubit is larger than the number of qubits" << std::endl;
        print(sstream, 0);         
        throw sstream.str();
    }
    // The index of the qubit which acts as a control qubit (control_qbit >= 0) in controlled gates
    control_qbit = control_qbit_in;

    // Parameter of the gate after the decomposition of the unitary is done
    parameters = Matrix_real(1, parameter_num);

}

CZ_NU::~CZ_NU() {
}

Matrix
CZ_NU::get_matrix( Matrix_real& parameters ) {

    return get_matrix( parameters, false );
}


Matrix
CZ_NU::get_matrix( Matrix_real& parameters, int parallel) {

    Matrix CZ_matrix = create_identity(matrix_size);
    apply_to(  parameters, CZ_matrix, parallel);

    return CZ_matrix;
}




void 
CZ_NU::apply_to( Matrix_real& parameters, Matrix& input, int parallel ) {

    if (input.rows != matrix_size ) {
        std::string err("CZ_NU::apply_to: Wrong matrix size in CZ_NU gate apply.");
        throw err;    
    }

    double param = parameters[0];

    Matrix u3_1qbit = calc_one_qubit_u3( param );
    apply_kernel_to(u3_1qbit, input, false, parallel);

}



void 
CZ_NU::apply_from_right( Matrix_real& parameters, Matrix& input ) {

    if (input.cols != matrix_size ) {
     std::stringstream sstream;
     sstream << "Wrong matrix size in CRY apply_from_right" << std::endl;
        print(sstream, 0);    
        throw "Wrong matrix size in CRY apply_from_right";
    }
    
    double param = parameters[0];
    
    Matrix u3_1qbit = calc_one_qubit_u3( param );
    apply_kernel_from_right(u3_1qbit, input);

}


void 
CZ_NU::apply_to_list( Matrix_real& parameters_mtx, std::vector<Matrix>& inputs, int parallel ) {

    int work_batch = 1;
    if ( parallel == 0 ) {
        work_batch = inputs.size();
    }
    else {
        work_batch = 1;
    }


    tbb::parallel_for( tbb::blocked_range<int>(0,inputs.size(),work_batch), [&](tbb::blocked_range<int> r) {
        for (int idx=r.begin(); idx<r.end(); ++idx) { 

            Matrix* input = &inputs[idx];

            apply_to( parameters_mtx, *input, parallel );

        }

    });


}


std::vector<Matrix> 
CZ_NU::apply_derivate_to( Matrix_real& parameters_mtx, Matrix& input, int parallel ) {

    if (input.rows != matrix_size ) {
     std::stringstream sstream;
     sstream << "Wrong matrix size in CRY gate apply" << std::endl;
        print(sstream, 0);       
        throw "Wrong matrix size in CRY gate apply";
    }

    std::vector<Matrix> ret;

    double param = parameters_mtx[0]+M_PI/2;

    // the resulting matrix
    Matrix res_mtx = input.copy();   


    // get the gate kernel
    Matrix u3_1qbit = calc_one_qubit_u3( param );


    // apply the computing kernel on the matrix
    bool deriv = true;
    apply_kernel_to(u3_1qbit, res_mtx, deriv, parallel);

    ret.push_back(res_mtx);
    return ret;


}




void CZ_NU::set_optimized_parameters(double param ) {

    parameters = Matrix_real(1, parameter_num);

    parameters[0] = param;

}


Matrix_real CZ_NU::get_optimized_parameters() {

    return parameters.copy();

}



void CZ_NU::set_qbit_num(int qbit_num) {
        // setting the number of qubits
        Gate::set_qbit_num(qbit_num);

}



void CZ_NU::reorder_qubits( vector<int> qbit_list) {

        Gate::reorder_qubits(qbit_list);

}

Matrix 
CZ_NU::calc_one_qubit_u3( double& param ){

    Matrix u3_1qbit = Matrix(2,2);
    u3_1qbit[0].real = 1.0;         u3_1qbit[0].imag = 0.0; 
    u3_1qbit[1].real = 0.0;         u3_1qbit[1].imag = 0.0;
    u3_1qbit[2].real = 0.0;         u3_1qbit[2].imag = 0.0;
    u3_1qbit[3].real = cos( param); u3_1qbit[3].imag = 0.0;
    return u3_1qbit;

}

CZ_NU* CZ_NU::clone() {

    CZ_NU* ret = new CZ_NU( qbit_num, target_qbit, control_qbit );

    return ret;

}