def test_power_inplace(self):
"""Test inplace power method."""
# 10% depolarizing channel
rho = np.diag([1, 0])
p_id = 0.9
chan = Stinespring(self.depol_stine(1 - p_id))
# Compose 3 times
p_id3 = p_id**3
targ3a = chan._evolve(chan._evolve(chan._evolve(rho)))
targ3b = Stinespring(self.depol_stine(1 - p_id3))._evolve(rho)
chan.power(3, inplace=True)
self.assertAllClose(chan._evolve(rho), targ3a)
self.assertAllClose(chan._evolve(rho), targ3b)
def test_power(self):
"""Test power method."""
# 10% depolarizing channel
rho_init = DensityMatrix(np.diag([1, 0]))
p_id = 0.9
chan1 = Stinespring(self.depol_stine(1 - p_id))
# Compose 3 times
p_id3 = p_id**3
chan = chan1.power(3)
rho_targ = rho_init @ chan1 @ chan1 @ chan1
self.assertEqual(rho_init @ chan, rho_targ)
rho_targ = rho_init @ Stinespring(self.depol_stine(1 - p_id3))
self.assertEqual(rho_init @ chan, rho_targ)
