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- from graph import *
- import viz
- import itertools as it
- import clifford
-
- 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 """
- others = g[a] - {avoid}
- swap_qubit = others.pop() if others else avoid
- for v in reversed(clifford.decompositions[vops[a]]):
- local_complementation(g, vops, a if v == "x" else swap_qubit)
-
-
- def local_complementation(g, vops, v):
- """ As defined in LISTING 1 of Anders & Briegel """
- for i, j in it.combinations(g[v], 2):
- toggle_edge(g, i, j)
-
- # Update VOPs
- vops[v] = clifford.times_table[vops[v]][clifford.by_name["sqx"]]
- for i in g[v]:
- vops[i] = clifford.times_table[vops[i]][clifford.by_name["msqz"]]
-
-
- if __name__ == '__main__':
- g, vops = graph()
- add_edge(g, 0, 1)
- add_edge(g, 1, 2)
- add_edge(g, 0, 2)
- add_edge(g, 0, 3)
- add_edge(g, 6, 7)
-
- 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)
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