CNOT.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 "CNOT.h"


using namespace std;


CNOT::CNOT() {

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

    // 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 = CNOT_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 gate
    control_qbit = -1;


}


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


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

    // 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 = CNOT_OPERATION;

    // The number of free parameters
    parameter_num = 0;

    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 gate
    control_qbit = control_qbit_in;


}

CNOT::~CNOT() {
}

Matrix
CNOT::get_matrix() {

    return get_matrix( false );

}



Matrix
CNOT::get_matrix( int parallel) {

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

    return CNOT_matrix;

}



void 
CNOT::apply_to( Matrix& input, int parallel ) {
 
    if (input.rows != matrix_size ) {
        std::string err("CNOT::apply_to: Wrong input size in CNOT gate apply.");
        throw err;    
    }
    
    
    Matrix u3_1qbit = calc_one_qubit_u3();
    apply_kernel_to(u3_1qbit, input, false, parallel);
    



}



void 
CNOT::apply_from_right( Matrix& input ) {

    Matrix u3_1qbit = calc_one_qubit_u3();
    apply_kernel_from_right(u3_1qbit, input);



}




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

}



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

        Gate::reorder_qubits(qbit_list);

}

Matrix
CNOT::calc_one_qubit_u3( ){

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

CNOT* CNOT::clone() {

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

    return ret;

}