From 11368ba8809916f1265e83dcbec8d3a193397454 Mon Sep 17 00:00:00 2001
From: Pete Shadbolt <pete.shadbolt@gmail.com>
Date: Tue, 10 May 2016 22:55:22 +0100
Subject: [PATCH] Fix qi simulator again, test passing

---
 abp/graphstate.py              | 22 ++++++++++++++++++----
 abp/qi.py                      | 18 ++++++------------
 tests/test_get_state_vector.py | 15 +++++++++++++++
 tests/test_qi_circuit_model.py | 16 +++++++++++++---
 4 files changed, 52 insertions(+), 19 deletions(-)
 create mode 100644 tests/test_get_state_vector.py

diff --git a/abp/graphstate.py b/abp/graphstate.py
index 44f8b14..36d7e6b 100644
--- a/abp/graphstate.py
+++ b/abp/graphstate.py
@@ -6,6 +6,7 @@ from collections import defaultdict
 import itertools as it
 import clifford
 import json
+import qi
 try:
     import networkx as nx
 except ImportError:
@@ -139,8 +140,9 @@ class GraphState(object):
 
     def __str__(self):
         """ Represent as a string for quick debugging """
-        return "graph:\n vops: {}\n ngbh: {}\n"\
-                .format(str(dict(self.vops)), str(dict(self.ngbh)))
+        vopstr = {key: clifford.get_name(value) for key,value in self.vops.items()}
+        nbstr = str(dict(self.ngbh))
+        return "graph:\n vops: {}\n ngbh: {}\n".format(vopstr, nbstr)
 
     def to_json(self):
         """ Convert the graph to JSON form """
@@ -160,8 +162,20 @@ class GraphState(object):
         return g
 
     def to_state_vector(self):
-        """ Get the freaking state vector """
-        return None
+        """ Get the full state vector """
+        if not len(self.vops)<10:
+            raise ValueError("Cannot build state vector: too many qubits")
+        output = qi.CircuitModel(len(self.vops))
+        #print output
+        for i in range(len(self.vops)):
+            output.act_hadamard(i)
+        #print output
+        for i, j in self.edgelist():
+            output.act_cz(i, j)
+        #print output
+        for i, u in self.vops.items():
+            output.act_local_rotation(i, clifford.unitaries[u])
+        return output
 
     def layout(self):
         """ Automatically lay out the graph """
diff --git a/abp/qi.py b/abp/qi.py
index e942995..9584650 100644
--- a/abp/qi.py
+++ b/abp/qi.py
@@ -68,12 +68,9 @@ class CircuitModel(object):
         where = 1 << qubit
         output = np.zeros((self.d, 1), dtype=complex)
         for i, v in enumerate(self.state):
-            if (i & where) == 0:
-                output[i] += v*ir2
-                output[i ^ where] += v*ir2
-            if (i & where) == 1:
-                output[i ^ where] += v*ir2
-                output[i] -= v*ir2
+            q = i & where > 0
+            output[i] += v*ha[q, q]
+            output[i ^ where] += v*ha[not q, q]
         self.state = output
 
 
@@ -82,12 +79,9 @@ class CircuitModel(object):
         where = 1 << qubit
         output = np.zeros((self.d, 1), dtype=complex)
         for i, v in enumerate(self.state):
-            if (i & where) == 0:
-                output[i] += v*u[0, 0]
-                output[i ^ where] += v*u[0, 1]
-            if (i & where) == 1:
-                output[i ^ where] += v*u[1, 0]
-                output[i] += v*u[1, 1]
+            q = i & where > 0
+            output[i] += v*u[q, q]
+            output[i ^ where] += v*u[not q, q]
         self.state = output
 
 
diff --git a/tests/test_get_state_vector.py b/tests/test_get_state_vector.py
new file mode 100644
index 0000000..94bacf9
--- /dev/null
+++ b/tests/test_get_state_vector.py
@@ -0,0 +1,15 @@
+from abp.graphstate import GraphState
+from abp import qi
+import numpy as np
+
+def test_single_qubit():
+    """ Test some single-qubit stuff """
+    g = GraphState()
+    g.add_node(0)
+    g.add_node(1)
+    g.act_local_rotation_by_name(0, "hadamard")
+    g.act_local_rotation_by_name(1, "hadamard")
+    g.act_cz(0, 1)
+    assert np.allclose(g.to_state_vector().state, qi.bond)
+
+
diff --git a/tests/test_qi_circuit_model.py b/tests/test_qi_circuit_model.py
index 19c0ec4..c31c284 100644
--- a/tests/test_qi_circuit_model.py
+++ b/tests/test_qi_circuit_model.py
@@ -1,17 +1,21 @@
 import numpy as np
 from abp import qi
 
-def test_init():
+def _test_init():
     """ Can you initialize some qubits """
     psi = qi.CircuitModel(5)
     assert psi.d == 32
 
 def test_hadamard():
     """ What does CZ do ? """
-    psi = qi.CircuitModel(10)
+    psi = qi.CircuitModel(3)
     psi.act_hadamard(0)
+    psi.act_hadamard(1)
+    assert np.allclose(psi.state, np.array([[1,1,1,1,0,0,0,0]]).T/2.)
+    psi.act_hadamard(1)
     psi.act_hadamard(0)
-    assert np.allclose(psi.state[0], 1)
+    psi.act_hadamard(2)
+    assert np.allclose(psi.state, qi.ir2*np.array([[1,0,0,0,1,0,0,0]]).T)
 
 
 def test_cz():
@@ -30,4 +34,10 @@ def test_local_rotation():
     psi.act_local_rotation(0, qi.ha)
     assert np.allclose(psi.state[0], 1)
 
+    psi.act_local_rotation(0, qi.ha)
+    psi.act_local_rotation(1, qi.ha)
+    psi.act_local_rotation(0, qi.ha)
+    psi.act_local_rotation(1, qi.ha)
+    assert np.allclose(psi.state[0], 1)
+