SYC.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 "SYC.h"



using namespace std;


SYC::SYC() {

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

    // 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 = SYC_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;


}


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

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

    // 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 = SYC_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 "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;


    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 "The index of the control qubit is larger than the number of qubits";
    }
     
    // The index of the qubit which acts as a control qubit (control_qbit >= 0) in controlled gate
    control_qbit = control_qbit_in;

}

SYC::~SYC() {
}

Matrix
SYC::get_matrix() {


    return get_matrix( false );

}


Matrix
SYC::get_matrix( int parallel) {

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

    return SYC_matrix;

}


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

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

    int index_step_target = Power_of_2(target_qbit);
    int index_step_control = Power_of_2(control_qbit);

    int loopSize   = index_step_target < index_step_control ? index_step_target : index_step_control;
    int iterations = control_qbit < target_qbit ? Power_of_2(target_qbit-control_qbit-1) : Power_of_2(control_qbit-target_qbit-1);

    // |control, target>
    int idx00 = 0;
    int idx01 = index_step_target;
    int idx10 = index_step_control;
    int idx11 = index_step_target + index_step_control;

/*
std::cout << "target qubit: " << target_qbit << std::endl;
std::cout << "control qubit: " << control_qbit << std::endl;
std::cout << "iterations: " << iterations << std::endl;
std::cout << "loopSize: " << loopSize << std::endl;
*/
    while ( idx11 < matrix_size ) {

        for ( int jdx=0; jdx<iterations; jdx++ ) {

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

                // |control, target>
                //int idx00_loc = idx00 + idx;
                int idx01_loc = idx01 + idx;
                int idx10_loc = idx10 + idx;
                int idx11_loc = idx11 + idx;


                //int offset00 = idx00_loc*input.stride;
                int offset01 = idx01_loc*input.stride;
                int offset10 = idx10_loc*input.stride;
                int offset11 = idx11_loc*input.stride;


                for (int col_idx=0; col_idx<input.cols; col_idx++) {

                    // transform elements 10 and 01
                    QGD_Complex16 element01 = input[ offset01 + col_idx ];
                    QGD_Complex16 element10 = input[ offset10 + col_idx ];
                    input[ offset01 + col_idx ].real = element10.imag;
                    input[ offset01 + col_idx ].imag = -element10.real;

                    input[ offset10 + col_idx ].real = element01.imag;
                    input[ offset10 + col_idx ].imag = -element01.real;


                    // transform element 11
                    QGD_Complex16 element11 = input[ offset11 + col_idx ];
                    QGD_Complex16 factor;
                    factor.real = sqrt(3)/2;
                    factor.imag = -0.5;
                    input[ offset11 + col_idx ] = mult(element11, factor);
                }

            

    //std::cout << current_idx_target << " " << current_idx_target_pair << std::endl;


            });

        

            idx00 = idx00 + 2*loopSize;
            idx01 = idx01 + 2*loopSize;
            idx10 = idx10 + 2*loopSize;
            idx11 = idx11 + 2*loopSize;


        }


        idx00 = idx00 + 2*loopSize*iterations;
        idx01 = idx01 + 2*loopSize*iterations;
        idx10 = idx10 + 2*loopSize*iterations;
        idx11 = idx11 + 2*loopSize*iterations;


    }


}


void 
SYC::apply_from_right( Matrix& input ) {
/*
Matrix SYC_gate = get_matrix();
SYC_gate.print_matrix();
Matrix res = dot(input, SYC_gate);
memcpy( input.get_data(), res.get_data(), res.size()*sizeof(QGD_Complex16) );
return;
*/
    int index_step_target = Power_of_2(target_qbit);
    int index_step_control = Power_of_2(control_qbit);

    int loopSize   = index_step_target < index_step_control ? index_step_target : index_step_control;
    int iterations = control_qbit < target_qbit ? Power_of_2(target_qbit-control_qbit-1) : Power_of_2(control_qbit-target_qbit-1);



    // loop over the rows of the input matrix
    tbb::parallel_for(0, matrix_size, 1, [&](int idx) {  

        int offset = idx*input.stride;
        
        // |control, target>
        int idx00 = 0;
        int idx01 = index_step_target;
        int idx10 = index_step_control;
        int idx11 = index_step_target + index_step_control;

        while ( idx11 < matrix_size ) {

            for ( int jdx=0; jdx<iterations; jdx++ ) {


                for ( int idx=0; idx<loopSize; idx++ ) {

                    // |control, target>
                    //int idx00_loc = idx00 + idx;
                    int idx01_loc = idx01 + idx;
                    int idx10_loc = idx10 + idx;
                    int idx11_loc = idx11 + idx;

                    // transform elements 10 and 01
                    QGD_Complex16 element01 = input[ offset + idx01_loc ];
                    QGD_Complex16 element10 = input[ offset + idx10_loc ];
                    input[ offset + idx01_loc ].real = element10.imag;
                    input[ offset + idx01_loc ].imag = -element10.real;

                    input[ offset + idx10_loc ].real = element01.imag;
                    input[ offset + idx10_loc ].imag = -element01.real;


                    // transform element 11
                    QGD_Complex16 element11 = input[ offset + idx11_loc ];
                    QGD_Complex16 factor;
                    factor.real = sqrt(3)/2;
                    factor.imag = -0.5;
                    input[ offset + idx11_loc ] = mult(element11, factor);

                }

                idx00 = idx00 + 2*loopSize;
                idx01 = idx01 + 2*loopSize;
                idx10 = idx10 + 2*loopSize;
                idx11 = idx11 + 2*loopSize;


            }

            idx00 = idx00 + 2*loopSize*iterations;
            idx01 = idx01 + 2*loopSize*iterations;
            idx10 = idx10 + 2*loopSize*iterations;
            idx11 = idx11 + 2*loopSize*iterations;

        }

    });


}



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

}



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

        Gate::reorder_qubits(qbit_list);

}



SYC* SYC::clone() {

    SYC* ret = new SYC( 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;

}