qc-sim/quantumcomputation.py at master · sysoevss/qc-sim · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
from google.appengine.ext import db

import math
import random

class QC:
    status = 0.0
    guid = ''

    def __init__(self, guid):
        self.status = 0.0
        self.guid = guid

    def getStatus(self):
        return str(self.status)

    '''
    '  Creates input state
    '
    '''
    def createState(self, schema):
        x = int(schema.split('}')[0][1:].replace(',', '')[::-1], base = 2)
        n = len(schema.split('}')[0][1:].replace(',', ''))
        N = 2 ** n
        state = []
        for i in range(N):
            state.append(complex(0, 0))

        state[x] = complex(1, 0)
        self.status = 0
        return state, n, N

    '''
    '  Applies cirsuit scheme to the input
    '
    '''
    def applyScheme(self, state, schema, n):
        gates = schema.split('}')[1][1:].split(',')

        for t in range(0, len(gates), n):
            tact = gates[t : t + n]

            # find the control bit if exists
            control = []
            for i in range(len(tact)):
                if tact[i] == '*':
                    control.append(i)

            # Apply gates in tact
            qbit = 0
            for gate in tact:
                state = self.applyGate(state, qbit, n, gate, control)
                qbit += 1
                self.status += 100.0 / len(gates)

        return state

    '''
    '  Applies the gate
    '
    '''
    def qubitGate(self, c_i, result, i, n, qbit, A, B, C, D):
        base = 2 ** qbit
        if i & base:                # qubit is |1> so B,D column is applied
            result[i] = result[i] + c_i * D
            i2 = i - base
            result[i2] = result[i2] + c_i * B
        else:                       # qubit is |0> so A,C column is applied
            result[i] = result[i] + c_i * A
            i2 = i + base
            result[i2] = result[i2] + c_i * C

        return result

    def applyGate(self, state, qbit, n, gate, control):
        # skip on identity and control symbol
        if gate == 'I' or gate == '*':
            return state

        # main cycle
        N = 2 ** n
        result = []
        for i in range(N):
            result.append(complex(0,0))
        for i in range(N):
            # check if basis vector i is in superposition
            if state[i] == complex(0, 0):
                continue
            # check if gate is controlled and if any of control bits is 0, then do nothing
            res_control = True
            for c in control:
                if not (2 ** c & i):
                    res_control = False

            if not res_control:
                result[i] = state[i]
                continue

            # at last, do the computation
            if gate == 'H':
                sqrt2 = complex(1 / math.sqrt(2), 0)
                result = self.qubitGate(state[i], result, i, n, qbit, sqrt2, sqrt2, sqrt2, -sqrt2)

            if gate[0] == 'R':
                angle = 2 * math.pi / 2 ** int(gate[1])
                phase = complex(math.cos(angle), math.sin(angle))
                result = self.qubitGate(state[i], result, i, n, qbit, complex(1,0), complex(0,0), complex(0,0), phase)

            if gate[0] == 'Z':
                result = self.qubitGate(state[i], result, i, n, qbit, complex(1,0), complex(0,0), complex(0,0), complex(-1,0))

            if gate[0] == 'X':
                result = self.qubitGate(state[i], result, i, n, qbit, complex(0,0), complex(1,0), complex(1,0), complex(0,0))

        return result


    def measure(self, state):
        for i in range(len(state)):
            state[i] = state[i].real * state[i].real + state[i].imag * state[i].imag

        r = random.random()
        temp = 0
        for i in range(len(state)):
            temp += state[i]
            if temp >= r:
                return bin(i)

        return bin(len(state) - 1)

'''
'  Measurement
'
'''
def bin(n):
    return "".join([["0", "1"][(n >> i) & 1] for i in reversed(range(20))])