def test_fidelity_product_states():
a, b = cirq.LineQubit.range(2)
np.testing.assert_allclose(
cirq.fidelity(cirq.KET_ZERO(a) * cirq.KET_ZERO(b), cirq.KET_ZERO(a) * cirq.KET_ZERO(b)), 1.0
)
np.testing.assert_allclose(
cirq.fidelity(cirq.KET_ZERO(a) * cirq.KET_ZERO(b), cirq.KET_ZERO(a) * cirq.KET_ONE(b)),
0.0,
atol=1e-7,
)
np.testing.assert_allclose(
cirq.fidelity(cirq.KET_ZERO(a) * cirq.KET_ZERO(b), cirq.KET_ZERO(a) * cirq.KET_PLUS(b)), 0.5
)
np.testing.assert_allclose(
cirq.fidelity(cirq.KET_ONE(a) * cirq.KET_ONE(b), cirq.KET_MINUS(a) * cirq.KET_PLUS(b)), 0.25
)
np.testing.assert_allclose(
cirq.fidelity(cirq.KET_MINUS(a) * cirq.KET_PLUS(b), cirq.KET_MINUS(a) * cirq.KET_PLUS(b)),
1.0,
)
np.testing.assert_allclose(
cirq.fidelity(cirq.KET_MINUS(a) * cirq.KET_PLUS(b), cirq.KET_PLUS(a) * cirq.KET_MINUS(b)),
0.0,
atol=1e-7,
)
with pytest.raises(ValueError, match='Mismatched'):
_ = cirq.fidelity(cirq.KET_MINUS(a), cirq.KET_PLUS(a) * cirq.KET_MINUS(b))
with pytest.raises(ValueError, match='qid shape'):
_ = cirq.fidelity(
cirq.KET_MINUS(a) * cirq.KET_PLUS(b),
cirq.KET_PLUS(a) * cirq.KET_MINUS(b),
qid_shape=(4,),
)
def test_tp_projector():
q0, q1 = cirq.LineQubit.range(2)
p00 = (cirq.KET_ZERO(q0) * cirq.KET_ZERO(q1)).projector()
rho = cirq.final_density_matrix(cirq.Circuit(cirq.I.on_each(q0, q1)))
np.testing.assert_allclose(rho, p00)
p01 = (cirq.KET_ZERO(q0) * cirq.KET_ONE(q1)).projector()
rho = cirq.final_density_matrix(cirq.Circuit([cirq.I.on_each(q0, q1), cirq.X(q1)]))
np.testing.assert_allclose(rho, p01)
ppp = (cirq.KET_PLUS(q0) * cirq.KET_PLUS(q1)).projector()
rho = cirq.final_density_matrix(
cirq.Circuit(
[
cirq.H.on_each(q0, q1),
]
)
)
np.testing.assert_allclose(rho, ppp, atol=1e-7)
ppm = (cirq.KET_PLUS(q0) * cirq.KET_MINUS(q1)).projector()
rho = cirq.final_density_matrix(cirq.Circuit([cirq.H.on_each(q0, q1), cirq.Z(q1)]))
np.testing.assert_allclose(rho, ppm, atol=1e-7)
pii = (cirq.KET_IMAG(q0) * cirq.KET_IMAG(q1)).projector()
rho = cirq.final_density_matrix(cirq.Circuit(cirq.rx(-np.pi / 2).on_each(q0, q1)))
np.testing.assert_allclose(rho, pii, atol=1e-7)
pij = (cirq.KET_IMAG(q0) * cirq.KET_MINUS_IMAG(q1)).projector()
rho = cirq.final_density_matrix(cirq.Circuit(cirq.rx(-np.pi / 2)(q0), cirq.rx(np.pi / 2)(q1)))
np.testing.assert_allclose(rho, pij, atol=1e-7)
def test_tp_initial_state():
q0, q1 = cirq.LineQubit.range(2)
psi1 = cirq.final_state_vector(cirq.Circuit([cirq.I.on_each(q0, q1), cirq.X(q1)]))
s01 = cirq.KET_ZERO(q0) * cirq.KET_ONE(q1)
psi2 = cirq.final_state_vector(cirq.Circuit([cirq.I.on_each(q0, q1)]), initial_state=s01)
np.testing.assert_allclose(psi1, psi2)
def test_tp_state_vector():
q0, q1 = cirq.LineQubit.range(2)
s00 = cirq.KET_ZERO(q0) * cirq.KET_ZERO(q1)
np.testing.assert_equal(s00.state_vector(), [1, 0, 0, 0])
np.testing.assert_equal(s00.state_vector(qubit_order=(q1, q0)), [1, 0, 0, 0])
s01 = cirq.KET_ZERO(q0) * cirq.KET_ONE(q1)
np.testing.assert_equal(s01.state_vector(), [0, 1, 0, 0])
np.testing.assert_equal(s01.state_vector(qubit_order=(q1, q0)), [0, 0, 1, 0])
def test_simulate_tps_initial_state():
q0, q1 = cirq.LineQubit.range(2)
simulator = cirq.DensityMatrixSimulator()
for b0 in [0, 1]:
for b1 in [0, 1]:
circuit = cirq.Circuit((cirq.X ** b0)(q0), (cirq.X ** b1)(q1))
result = simulator.simulate(circuit, initial_state=cirq.KET_ZERO(q0) * cirq.KET_ONE(q1))
expected_density_matrix = np.zeros(shape=(4, 4))
expected_density_matrix[b0 * 2 + 1 - b1, b0 * 2 + 1 - b1] = 1.0
np.testing.assert_equal(result.final_density_matrix, expected_density_matrix)
def test_quantum_state_product_state():
q0, q1, q2 = cirq.LineQubit.range(3)
product_state_1 = cirq.KET_PLUS(q0) * cirq.KET_PLUS(q1) * cirq.KET_ONE(q2)
state = cirq.quantum_state(product_state_1)
np.testing.assert_allclose(state.data, product_state_1.state_vector())
assert state.qid_shape == (2, 2, 2)
assert state.dtype == np.complex64
with pytest.raises(ValueError, match='qid shape'):
_ = cirq.quantum_state(product_state_1, qid_shape=(2, 2))
def test_product_state():
q0, q1, q2 = cirq.LineQubit.range(3)
ps = cirq.KET_PLUS(q0) * cirq.KET_PLUS(q1)
assert str(ps) == "+X(0) * +X(1)"
ps *= cirq.KET_ONE(q2)
assert str(ps) == "+X(0) * +X(1) * -Z(2)"
with pytest.raises(ValueError) as e:
# Re-use q2
ps *= cirq.KET_PLUS(q2)
assert e.match(r'.*both contain factors for these qubits: ' r'\[cirq.LineQubit\(2\)\]')
ps2 = eval(repr(ps))
assert ps == ps2
