def test_program_subroutine(self, setup_eng, tol):
"""Simple quantum program with a subroutine and references."""
eng, prog = setup_eng(2)
# define some gates
D = ops.Dgate(0.5)
BS = ops.BSgate(0.7 * np.pi, np.pi / 2)
R = ops.Rgate(np.pi / 3)
def subroutine(a, b):
"""Subroutine for the quantum program"""
R | a
BS | (a, b)
R.H | a
# main program
with prog.context as q:
# get register references
alice, bob = q
ops.All(ops.Vacuum()) | (alice, bob)
D | alice
subroutine(alice, bob)
BS | (alice, bob)
subroutine(bob, alice)
state = eng.run(prog).state
# state norm must be invariant
if isinstance(eng.backend, BaseFock):
assert np.allclose(state.trace(), 1, atol=tol, rtol=0)
def test_merge(self, state):
"""Test that merging states simply returns the second state"""
# state to test against
V = ops.Vacuum()
G = state()
# merging with another state returns the last one
assert np.all(G.merge(V) == V)
assert np.all(V.merge(G) == G)
