From 3cf5c2d901c74f68af26282a7b917d617e29d23f Mon Sep 17 00:00:00 2001
From: Pete Shadbolt <pete.shadbolt@gmail.com>
Date: Thu, 10 Mar 2016 21:24:19 +0000
Subject: [PATCH] Tentative CZ implementation

---
 cz.py  | 14 +++++++++++---
 viz.py | 10 ----------
 2 files changed, 11 insertions(+), 13 deletions(-)

diff --git a/cz.py b/cz.py
index e1cfab7..cfc60ea 100644
--- a/cz.py
+++ b/cz.py
@@ -3,9 +3,16 @@ import viz
 import itertools as it
 import clifford
 
-#def cphase(a, b):
-    #""" Act a controlled-phase gate on two qubits """
-    #if g
+def cphase(g, vops, a, b):
+    """ Act a controlled-phase gate on two qubits """
+    if g[a]-{b}: remove_vop(g, vops, a, b)
+    if g[b]-{a}: remove_vop(g, vops, b, a)
+    if g[a]-{b}: remove_vop(g, vops, a, b)
+    edge = has_edge(g, a, b)
+    new_edge, vops[a], vops[b] = cphase_table[edge, vops[a], vops[b]]
+    if new_edge != edge:
+        toggle_edge(g, a, b)
+    
 
 def remove_vop(g, vops, a, avoid):
     """ Reduces VOP[a] to the identity, avoiding (if possible) the use of vertex b as a swapping partner """
@@ -37,4 +44,5 @@ if __name__ == '__main__':
     pos = viz.draw(g, vops, "out.pdf")
     remove_vop(g, vops, 0, 1)
     remove_vop(g, vops, 1, 2)
+    cphase(g, vops, 0, 1)
     viz.draw(g, vops, "out2.pdf", pos)
diff --git a/viz.py b/viz.py
index 3ecae72..ab9f643 100644
--- a/viz.py
+++ b/viz.py
@@ -28,13 +28,3 @@ def draw(graph, vops, filename="out.pdf", pos=None, ns=500):
     plt.savefig(filename)
     return pos
 
-if __name__ == '__main__':
-    g, vops = graph()
-    add_edge(g, 0, 1)
-    add_edge(g, 1, 3)
-    add_edge(g, 3, 2)
-    add_edge(g, 3, 0)
-    add_edge(g, 2, 0)
-    edgelist(g)
-    draw(g, vops)
-