def test_trotter_hamiltonian_make_compatible_repeating(nqubits):
"""Check ``make_compatible`` when first target is repeated in parts."""
h0target = X(nqubits)
h0 = X(nqubits, trotter=True)
term = TFIM(2, numpy=True)
parts = [{(0, i): term} for i in range(1, nqubits)]
parts.extend(({(i, 0): term} for i in range(1, nqubits)))
h1 = TrotterHamiltonian(*parts)
h0c = h1.make_compatible(h0)
assert not h1.is_compatible(h0)
assert h1.is_compatible(h0c)
np.testing.assert_allclose(h0c.matrix, h0target.matrix)
def test_trotter_hamiltonian_make_compatible_simple():
"""Test ``make_compatible`` on a simple 3-qubit example."""
h0target = X(3)
h0 = X(3, trotter=True)
term1 = Y(1, numpy=True)
term2 = TFIM(2, numpy=True)
parts = [{(0, 1): term2, (1, 2): term2, (0, 2): term2, (2, ): term1}]
h1 = TrotterHamiltonian(*parts)
h0c = h1.make_compatible(h0)
assert not h1.is_compatible(h0)
assert h1.is_compatible(h0c)
np.testing.assert_allclose(h0c.matrix, h0target.matrix)
def test_from_symbolic_application_hamiltonian():
"""Check ``from_symbolic`` for a specific four-qubit Hamiltonian."""
import sympy
z1, z2, z3, z4 = sympy.symbols("z1 z2 z3 z4")
symmap = {z: (i, matrices.Z) for i, z in enumerate([z1, z2, z3, z4])}
symham = (z1 * z2 - 0.5 * z1 * z3 + 2 * z2 * z3 + 0.35 * z2 +
0.25 * z3 * z4 + 0.5 * z3 + z4 - z1)
# Check that Trotter dense matrix agrees will full Hamiltonian matrix
fham = Hamiltonian.from_symbolic(symham, symmap)
tham = TrotterHamiltonian.from_symbolic(symham, symmap)
np.testing.assert_allclose(tham.dense.matrix, fham.matrix)
# Check that no one-qubit terms exist in the Trotter Hamiltonian
# (this means that merging was successful)
first_targets = set()
for part in tham.parts:
for targets, term in part.items():
first_targets.add(targets[0])
assert len(targets) == 2
assert term.nqubits == 2
assert first_targets == set(range(4))
# Check making an ``X`` Hamiltonian compatible with ``tham``
xham = X(nqubits=4, trotter=True)
cxham = tham.make_compatible(xham)
assert not tham.is_compatible(xham)
assert tham.is_compatible(cxham)
np.testing.assert_allclose(xham.dense.matrix, cxham.dense.matrix)
def test_trotter_hamiltonian_make_compatible(nqubits):
"""Test that ``make_compatible`` method works for ``X`` Hamiltonian."""
h0target = X(nqubits)
h0 = X(nqubits, trotter=True)
h1 = XXZ(nqubits, delta=0.5, trotter=True)
assert not h1.is_compatible(h0)
assert not h0.is_compatible(h1)
np.testing.assert_allclose(h0.matrix, h0target.matrix)
h0c = h1.make_compatible(h0)
assert not h1.is_compatible(h0)
assert h1.is_compatible(h0c)
assert h0c.is_compatible(h1)
np.testing.assert_allclose(h0.matrix, h0target.matrix)
np.testing.assert_allclose(h0c.matrix, h0target.matrix)
# for coverage
h0c = h1.make_compatible(h0c)
assert not h1.is_compatible("test")
h2 = XXZ(nqubits, delta=0.5, trotter=True)
h2.parts[0].pop((0, 1))
assert not h1.is_compatible(h2)
def test_trotter_hamiltonian_make_compatible_redundant():
"""Test ``make_compatible`` with redudant two-qubit terms."""
h0 = X(2, trotter=True)
target_matrix = h0.dense.matrix.numpy()
target_matrix = np.kron(target_matrix, np.eye(2,
dtype=target_matrix.dtype))
parts = [{(0, 1, 2): TFIM(3, numpy=True)}]
h1 = TrotterHamiltonian(*parts)
h0c = h1.make_compatible(h0)
assert not h1.is_compatible(h0)
assert h1.is_compatible(h0c)
np.testing.assert_allclose(h0c.matrix, target_matrix)
def test_x_hamiltonian_from_symbols(nqubits, trotter):
"""Check creating sum(X) Hamiltonian using sympy."""
import sympy
x_symbols = sympy.symbols(" ".join((f"X{i}" for i in range(nqubits))))
symham = -sum(x_symbols)
symmap = {x: (i, matrices.X) for i, x in enumerate(x_symbols)}
target_matrix = X(nqubits).matrix
if trotter:
trotter_ham = TrotterHamiltonian.from_symbolic(symham, symmap)
final_matrix = trotter_ham.dense.matrix
else:
full_ham = Hamiltonian.from_symbolic(symham, symmap)
final_matrix = full_ham.matrix
np.testing.assert_allclose(final_matrix, target_matrix)
def test_trotter_hamiltonian_make_compatible_onequbit_terms():
"""Check ``make_compatible`` when the two-qubit Hamiltonian has one-qubit terms."""
term1 = Hamiltonian(1, matrices.Z, numpy=True)
term2 = Hamiltonian(2, np.kron(matrices.Z, matrices.Z), numpy=True)
terms = {
(0, 1): term2,
(0, 2): -0.5 * term2,
(1, 2): 2 * term2,
(1, ): 0.35 * term1,
(2, 3): 0.25 * term2,
(2, ): 0.5 * term1,
(3, ): term1
}
tham = TrotterHamiltonian.from_dictionary(terms) + 1.5
xham = X(nqubits=4, trotter=True)
cxham = tham.make_compatible(xham)
assert not tham.is_compatible(xham)
assert tham.is_compatible(cxham)
np.testing.assert_allclose(xham.dense.matrix, cxham.dense.matrix)
def test_trotter_hamiltonian_operation_errors():
"""Test errors in ``TrotterHamiltonian`` addition and subtraction."""
# test addition with different number of parts
h1 = TFIM(nqubits=5, trotter=True)
term = TFIM(nqubits=2, numpy=True)
h2 = TrotterHamiltonian({
(0, 1): term,
(2, 3): term,
(4, 0): term
}, {
(1, 2): term,
(3, 4): term
})
with pytest.raises(ValueError):
h = h1 + h2
# test subtraction with incompatible parts
h2 = TrotterHamiltonian({
(0, 1): term,
(2, 3): term
}, {(1, 2): term}, {(4, 0): term})
with pytest.raises(ValueError):
h = h1 - h2
# test matmul with bad type
with pytest.raises(NotImplementedError):
s = h1 @ "abc"
# test matmul with bad shape
with pytest.raises(ValueError):
s = h1 @ np.zeros((2, 2))
# test ``make_compatible`` with non-Trotter Hamiltonian
with pytest.raises(TypeError):
h2 = h1.make_compatible("test")
# test ``make_compatible`` with interacting Hamiltonian
with pytest.raises(NotImplementedError):
h2 = h1.make_compatible(h2)
# test ``make_compatible`` with insufficient two-qubit terms
h3 = X(nqubits=7, trotter=True)
with pytest.raises(ValueError):
h3 = h1.make_compatible(h3)