InvFourier.java

/*-
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package org.redfx.strange.gate;

import org.redfx.strange.Complex;
import org.redfx.strange.QuantumExecutionEnvironment;

/**
 * <p>InvFourier class.</p>
 *
 * @author alain
 * @version $Id: $Id
 */
public class InvFourier extends Fourier {
    
    /**
     * Create a Fourier gate with the given size (dimensions), starting at idx
     *
     * @param size number of qubits affected by this gate
     * @param idx the index of the first qubit in the circuit affected by this gate
     */
    public InvFourier(int size, int idx) {
        super("InvFourier", size, idx);
    }
    
    /** {@inheritDoc} */
    @Override
    public Complex[][] getMatrix() {
        return getMatrix(null);
    }
    
    /** {@inheritDoc} */
    @Override
    public Complex[][] getMatrix(QuantumExecutionEnvironment eqq) {
        if (matrix == null) {
            double omega = Math.PI*2/size;
            double den = Math.sqrt(size);
            matrix = new Complex[size][size];
            for (int i = 0; i < size; i++) {
                for (int j = i; j < size; j++) {
                    double alpha = omega *i *j;
                    int tpd = (int)(alpha/(Math.PI * 2));
                    if (tpd > 0) {
                        alpha = alpha - (Math.PI*2 * tpd);
                    }
                    double ar = Math.cos(alpha);
                    double ai = Math.sin(alpha);
                    if (Math.abs(alpha) < 1e-6) {
                        ar = 1;
                        ai = 0;
                    }else if (Math.abs(Math.PI - alpha) < 1e-6) {
                        ar = -1;
                        ai = 0;
                    } else if (Math.abs(Math.PI / 2 - alpha) < 1e-6) {
                        ar = 0;
                        ai = 1;
                    } else if (Math.abs(3 * Math.PI / 2 - alpha) < 1e-6) {
                        ar = 0;
                        ai = -1;
                    }
                    matrix[i][j] = new Complex(ar/den, -1*ai/den);
                }
                for (int k = 0; k < i; k++) {
                    matrix[i][k] = matrix[k][i];
                }
            }
        }
        return matrix;
    }
    
    /** {@inheritDoc} */
    @Override
    public boolean hasOptimization() {
        return false;
    }
}