#!/usr/bin/python
#
# qclib - Quantum Computing library for Python
# Copyright (C) 2006 Robert Nowotniak
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see .
from qclib import *
import sys
N = 2 ** 3
n = N - 3
steps = int(floor(math.pi * 1.0/(math.asin(sqrt(1.0 / N))) / 4))
print 'Total numer of steps: ' + str(steps)
print
# identity gate
I = Identity(3)
w0 = Ket(n)
# initial state of quantum register
phi0 = QRegister([ones(N) / sqrt(N)])
# computation gates
A = I - 2 * w0.outer(w0)
B = 2 * phi0.outer(phi0) - I
phi = phi0
step = 0
print A*B
while step <= steps:
print 'Step number: ' + str(step)
print '----------------'
print 'Probability of search success: ',
print '%0.4f' % abs(float(phi.matrix[n]))**2
print
if step < steps:
phi = B(A(phi))
step += 1
print 'Final quantum register |phi> state: '
print phi
print
print 'Probability of search success: ',
print '%0.4f' % abs(float(phi.matrix[n]))**2
print
print 'Correct element: ', n
print 'State after measurement: ', phi.measure().dirac(binary = False)