def test_bigger(self):
psi = qu.rand_ket(2**5)
assert np.sum(abs(psi) < 1e-12) == 0
A = qu.kronpow(qu.pauli('Z'), 5)
res, psi_after = qu.measure(psi, A, eigenvalue=-1.0)
# should have projected to half subspace
assert np.sum(abs(psi_after) < 1e-12) == 2**4
assert res == -1.0
def test_mixed(self):
rho = qu.dop(qu.bell_state('psi-'))
IZ = qu.pauli('I') & qu.pauli('Z')
ZI = qu.pauli('Z') & qu.pauli('I')
res, rho_after = qu.measure(rho, IZ)
# normalized
assert qu.tr(rho_after) == pytest.approx(1.0)
# anticorrelated
assert qu.expectation(rho_after, IZ) == pytest.approx(res)
assert qu.expectation(rho_after, ZI) == pytest.approx(-res)
assert isinstance(rho_after, qu.qarray)
def test_pure(self):
psi = qu.bell_state('psi-')
IZ = qu.pauli('I') & qu.pauli('Z')
ZI = qu.pauli('Z') & qu.pauli('I')
res, psi_after = qu.measure(psi, IZ)
# normalized
assert qu.expectation(psi_after, psi_after) == pytest.approx(1.0)
# anticorrelated
assert qu.expectation(psi_after, IZ) == pytest.approx(res)
assert qu.expectation(psi_after, ZI) == pytest.approx(-res)
assert isinstance(psi_after, qu.qarray)