to from angles

06_krisis.py

@@ -0,0 +1,25 @@
+import cirq
+from math import pi
+
+
+def superdense():
+    # Pick a qubit.
+    q0 = cirq.GridQubit(0, 0)
+
+    # Create a circuit
+    circuit = cirq.Circuit(
+        cirq.rx(pi/8).on(q0),
+        cirq.rz(pi/2).on(q0),
+        cirq.measure(q0, key='q0'),
+    )
+    print("Circuit:")
+    print(circuit)
+
+    simulator = cirq.Simulator()
+    result = simulator.run(circuit, repetitions=100)
+    print("Results:")
+    print(result)
+
+
+if __name__ == "__main__":
+    superdense()

lib_q_computer_math.py

@@ -93,6 +93,35 @@ class State(Matrix):
         super().__init__(m)
         self.name = name
 
+    @classmethod
+    def from_angles(cls, theta, phi):
+        m0 = np.cos(theta / 2)
+        m1 = np.sin(theta / 2) * np.power(np.e, (1j * phi))
+        m = m0 * _0 + m1 * _1
+        return cls(m.m)
+
+    def to_angles(self):
+        if not self.m.shape == (2, 1):
+            raise Exception("State needs to be 2x1 matrix")
+        m0, m1 = self.m[0][0], self.m[1][0]
+
+        # theta is between 0 and pi
+        theta = 2 * np.arccos(m0)
+        if theta < 0:
+            theta += np.pi
+        assert 0 <= theta <= np.pi
+
+        div = np.sin(theta/2)
+        if div == 0:
+            phi = 0
+        else:
+            exp = m1 / div
+            phi = np.log(complex(exp)) / 1j
+            if phi < 0:
+                phi += 2 * np.pi
+        assert 0 <= phi <= 2 * np.pi
+        return theta, phi
+
     def __repr__(self):
         if self.name:
             return '|{}>'.format(self.name)
@@ -178,6 +207,22 @@ _1 = State([[0],
             [1]],
            name='1')
 
+_p = State([[1 / np.sqrt(2)], [1 / np.sqrt(2)]], name='+')
+
+_m = State([[1 / np.sqrt(2)], [-1 / np.sqrt(2)]], name='-')
+
+_00 = State([[1],
+             [0],
+             [0],
+             [0]],
+            name='00')
+
+_11 = State([[0],
+             [0],
+             [0],
+             [1]],
+            name='11')
+
 _ = I = UnitaryOperator([[1, 0],
                          [0, 1]],
                         name="-")
@@ -232,6 +277,7 @@ class TwoQubitGate(object):
 C = TwoQubitGate("C")
 x = TwoQubitGate("x")
 
+
 # TODO: End Hacky way to define 2-qbit gate
 ###########################################################
 
@@ -338,6 +384,26 @@ def test():
                                [0, 1]])
 
 
+def test_to_from_angles():
+    for q in [_0, _1, _p, _m]:
+        angles = q.to_angles()
+        s = State.from_angles(*angles)
+        assert q == s
+
+    assert State.from_angles(0, 0) == _0
+    assert State.from_angles(np.pi, 0) == _1
+    assert State.from_angles(np.pi / 2, 0) == _p
+    assert State.from_angles(np.pi / 2, np.pi) == _m
+    for theta, phi, qbit in [
+        (0, 0, _0),
+        (np.pi, 0, _1),
+        (np.pi / 2, 0, _p),
+        (np.pi / 2, np.pi, _m),
+    ]:
+        s = State.from_angles(theta, phi)
+        assert s == qbit
+
+
 def naive_load_test(N):
     import os
     import psutil
@@ -513,4 +579,12 @@ def test_quantum_processor():
 
 if __name__ == "__main__":
     test()
-    test_quantum_processor()
+    test_to_from_angles()
+
+    # test_quantum_processor()
+    # print(_1 | _0)
+    # qubit = _00 + _11
+    # print(qubit)
+    # bell = CNOT.on(qubit)
+    # HI = I*H
+    # print(bell)