SX.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 "SX.h"




//static tbb::spin_mutex my_mutex;
SX::SX() {

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

    // 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 = SX_OPERATION;

    // 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;

    parameter_num = 0;



}



SX::SX(int qbit_num_in, int target_qbit_in) {


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

    // 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 = SX_OPERATION;


    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 "The index of the target qubit is larger than the number of qubits";
    }
     
    // The index of the qubit on which the gate acts (target_qbit >= 0)
    target_qbit = target_qbit_in;
    // The index of the qubit which acts as a control qubit (control_qbit >= 0) in controlled gates
    control_qbit = -1;

    parameter_num = 0;


}


SX::~SX() {

}


Matrix
SX::get_matrix() {


        return get_matrix(false);

}



Matrix
SX::get_matrix( int parallel) {

        Matrix SX_matrix = create_identity(matrix_size);
        apply_to(SX_matrix, parallel);

#ifdef DEBUG
        if (SX_matrix.isnan()) {
            std::stringstream sstream;
         sstream << "SX::get_matrix: SX_matrix contains NaN." << std::endl;
            print(sstream, 1);       
        }
#endif

        return SX_matrix;

}



void 
SX::apply_to( Matrix& input, int parallel ) {

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


    Matrix u3_1qbit = calc_one_qubit_u3();

    //apply_kernel_to function to SX gate 
    apply_kernel_to( u3_1qbit, input, parallel );
   

}




void 
SX::apply_from_right( Matrix& input ) {


    if (input.cols != matrix_size ) {
        std::stringstream sstream;
     sstream << "Wrong matrix size in U3 apply_from_right" << std::endl;
        print(sstream, 0);    
        exit(-1);
    }


    Matrix u3_1qbit = calc_one_qubit_u3();    

    //apply_kernel_from_right function to SX gate 
    apply_kernel_from_right(u3_1qbit, input);

  /*  int index_step = Power_of_2(target_qbit);
    int current_idx = 0;
    int current_idx_pair = current_idx+index_step;

//std::cout << "target qbit: " << target_qbit << std::endl;

    while ( current_idx_pair < matrix_size ) {


        tbb::parallel_for(0, index_step, 1, [&](int idx) {  

            int current_idx_loc = current_idx + idx;
            int current_idx_pair_loc = current_idx_pair + idx;


            for ( int row_idx=0; row_idx<matrix_size; row_idx++) {

                int row_offset = row_idx*input.stride;


                int index      = row_offset+current_idx_loc;
                int index_pair = row_offset+current_idx_pair_loc;

                QGD_Complex16 element      = input[index];
                QGD_Complex16 element_pair = input[index_pair];

                QGD_Complex16 tmp1 = mult(sx_1qbit[0], element);
                QGD_Complex16 tmp2 = mult(sx_1qbit[2], element_pair);
                input[index].real = tmp1.real + tmp2.real;
                input[index].imag = tmp1.imag + tmp2.imag;

                tmp1 = mult(sx_1qbit[1], element);
                tmp2 = mult(sx_1qbit[3], element_pair);
                input[index_pair].real = tmp1.real + tmp2.real;
                input[index_pair].imag = tmp1.imag + tmp2.imag;

            };         

//std::cout << current_idx << " " << current_idx_pair << std::endl;

        });


        current_idx = current_idx + 2*index_step;
        current_idx_pair = current_idx_pair + 2*index_step;


    }
*/

}



SX* SX::clone() {

    SX* ret = new SX(qbit_num, target_qbit);
    
    ret->set_parameter_start_idx( get_parameter_start_idx() );
    ret->set_parents( parents );
    ret->set_children( children );

    return ret;

}




void SX::reorder_qubits( std::vector<int> qbit_list) {

    Gate::reorder_qubits(qbit_list);

}


void SX::set_qbit_num(int qbit_num_in) {

        // setting the number of qubits
        Gate::set_qbit_num(qbit_num_in);
}

Matrix
SX::calc_one_qubit_u3( ){
 
    Matrix u3_1qbit = Matrix(2,2);
    u3_1qbit[0].real = 0.5; u3_1qbit[0].imag = 0.5; 
    u3_1qbit[1].real = 0.5; u3_1qbit[1].imag = -0.5;
    u3_1qbit[2].real = 0.5; u3_1qbit[2].imag = -0.5;
    u3_1qbit[3].real = 0.5;u3_1qbit[3].imag = 0.5;
    return u3_1qbit;

}