def test_1x2_tf(self, hbar, tol):
"""Test a 1x2 lattice Bose-Hubbard model using TF"""
try:
import tensorflow as tf
except (ImportError, ModuleNotFoundError):
pytest.skip("TensorFlow not installed.")
if tf.__version__[:3] != "1.3":
pytest.skip("Incorrect TensorFlow version")
sf.hbar = hbar
prog = sf.Program(2)
H = bose_hubbard(1, 2, self.J, self.U)
with prog.context as q:
Fock(2) | q[0]
BoseHubbardPropagation(H, self.t, self.k) | q
eng = sf.Engine("tf", backend_options={"cutoff_dim": 7})
state = eng.run(prog).state
Hm = -self.J*np.sqrt(2)*np.array([[0, 1, 0], [1, 0, 1], [0, 1, 0]]) \
+ self.U*np.diag([1, 0, 1])
init_state = np.array([1, 0, 0])
exp = np.abs(np.dot(expm(-1j * self.t * Hm), init_state))**2
assert np.allclose(state.fock_prob([2, 0]), exp[0], rtol=tol)
assert np.allclose(state.fock_prob([1, 1]), exp[1], rtol=tol)
assert np.allclose(state.fock_prob([0, 2]), exp[2], rtol=tol)
def test_hbar_outside_context(self):
"""Tests setting hbar outside the engine"""
self.eng.reset()
q = self.eng.register
HBH = BoseHubbardPropagation(self.Hquad,
self.t,
self.k,
hbar=self.hbar)
with self.eng:
# pylint: disable=pointless-statement
Fock(2) | q[0]
HBH | q
state = self.eng.run('fock', cutoff_dim=7)
Hm = -self.J*np.sqrt(2)*np.array([[0, 1, 0], [1, 0, 1], [0, 1, 0]]) \
+ self.U*np.diag([1, 0, 1])
init_state = np.array([1, 0, 0])
exp = np.abs(np.dot(expm(-1j * self.t * Hm), init_state))**2
self.assertTrue(
np.allclose(state.fock_prob([2, 0]), exp[0], rtol=self.tol))
self.assertTrue(
np.allclose(state.fock_prob([1, 1]), exp[1], rtol=self.tol))
self.assertTrue(
np.allclose(state.fock_prob([0, 2]), exp[2], rtol=self.tol))
def test_circulant(self):
"""Test a 3-cycle Bose-Hubbard model in local mode"""
self.logTestName()
self.eng.reset()
q = self.eng.register
# tunnelling terms
H = BosonOperator('0 1^', -self.J) + BosonOperator('0^ 1', -self.J)
H += BosonOperator('0 2^', -self.J) + BosonOperator('0^ 2', -self.J)
H += BosonOperator('1 2^', -self.J) + BosonOperator('1^ 2', -self.J)
# on-site interactions
H += BosonOperator('0^ 0 0^ 0', 0.5 * self.U) - BosonOperator(
'0^ 0', 0.5 * self.U)
H += BosonOperator('1^ 1 1^ 1', 0.5 * self.U) - BosonOperator(
'1^ 1', 0.5 * self.U)
H += BosonOperator('2^ 2 2^ 2', 0.5 * self.U) - BosonOperator(
'2^ 2', 0.5 * self.U)
with self.eng:
Fock(2) | q[0]
BoseHubbardPropagation(H, self.t, 50) | q
state = self.eng.run('fock', cutoff_dim=3)
# 2D hamiltonian
A = np.array([[0, 1, 1], [1, 0, 1], [1, 1, 0]])
A2 = np.kron(A, np.identity(3)) + np.kron(np.identity(3), A)
# change of basis matrix
B = np.zeros([6, 9])
B[0, 0] = B[5, 8] = B[3, 4] = 1
B[1, 1] = B[1, 3] = 1 / np.sqrt(2)
B[2, 2] = B[2, 6] = 1 / np.sqrt(2)
B[4, 5] = B[4, 7] = 1 / np.sqrt(2)
# create Hamiltonian and add interaction term
Hm = B @ (self.J * A2) @ B.T
Hm[0, 0] = Hm[3, 3] = Hm[5, 5] = self.U
init_state = np.zeros([6])
init_state[0] = 1
exp = np.abs(np.dot(expm(-1j * self.t * Hm), init_state))**2
tol = 1e-1
self.assertTrue(
np.allclose(state.fock_prob([2, 0, 0]), exp[0], rtol=tol))
self.assertTrue(
np.allclose(state.fock_prob([1, 1, 0]), exp[1], rtol=tol))
self.assertTrue(
np.allclose(state.fock_prob([1, 0, 1]), exp[2], rtol=tol))
self.assertTrue(
np.allclose(state.fock_prob([0, 2, 0]), exp[3], rtol=tol))
self.assertTrue(
np.allclose(state.fock_prob([0, 1, 1]), exp[4], rtol=tol))
self.assertTrue(
np.allclose(state.fock_prob([0, 0, 2]), exp[5], rtol=tol))
def test_1x2_no_onsite(self, eng, tol):
"""Test a 1x2 lattice Bose-Hubbard model"""
prog = sf.Program(2)
H = bose_hubbard(1, 2, self.J, 0)
with prog.context as q:
Fock(2) | q[0]
BoseHubbardPropagation(H, self.t, self.k) | q
state = eng.run(prog).state
Hm = -self.J * np.sqrt(2) * np.array([[0, 1, 0], [1, 0, 1], [0, 1, 0]])
init_state = np.array([1, 0, 0])
exp = np.abs(np.dot(expm(-1j * self.t * Hm), init_state))**2
assert np.allclose(state.fock_prob([2, 0]), exp[0], rtol=tol)
assert np.allclose(state.fock_prob([1, 1]), exp[1], rtol=tol)
assert np.allclose(state.fock_prob([0, 2]), exp[2], rtol=tol)
def test_global(self, eng, tol):
"""Test a 1x2 lattice Bose-Hubbard model in global mode"""
prog = sf.Program(3)
with prog.context as q:
Sgate(0.1) | q[2]
Fock(2) | q[0]
BoseHubbardPropagation(self.H, self.t, self.k, mode='global') | q
state = eng.run(prog, run_options={"modes": [0, 1]}).state
Hm = -self.J*np.sqrt(2)*np.array([[0, 1, 0], [1, 0, 1], [0, 1, 0]]) \
+ self.U*np.diag([1, 0, 1])
init_state = np.array([1, 0, 0])
exp = np.abs(np.dot(expm(-1j * self.t * Hm), init_state))**2
assert np.allclose(state.fock_prob([2, 0]), exp[0], rtol=tol)
assert np.allclose(state.fock_prob([1, 1]), exp[1], rtol=tol)
assert np.allclose(state.fock_prob([0, 2]), exp[2], rtol=tol)
def test_1x2_quadrature_operators(self, eng, tol):
"""Test a 1x2 lattice Bose-Hubbard model by passing quadrature
operators instead of ladder operators"""
prog = sf.Program(2)
H = get_quad_operator(bose_hubbard(1, 2, self.J, self.U), hbar=2)
with prog.context as q:
Fock(2) | q[0]
BoseHubbardPropagation(H, self.t, self.k) | q
state = eng.run(prog).state
Hm = -self.J*np.sqrt(2)*np.array([[0, 1, 0], [1, 0, 1], [0, 1, 0]]) \
+ self.U*np.diag([1, 0, 1])
init_state = np.array([1, 0, 0])
exp = np.abs(np.dot(expm(-1j * self.t * Hm), init_state))**2
assert np.allclose(state.fock_prob([2, 0]), exp[0], rtol=tol)
assert np.allclose(state.fock_prob([1, 1]), exp[1], rtol=tol)
assert np.allclose(state.fock_prob([0, 2]), exp[2], rtol=tol)
def test_three_mode_fock_state_mean_photon(self, setup_eng, tol):
"""Tests that the mean photon numbers of a three-mode system,
where one mode is prepared in a Fock state, are correct."""
eng, prog = setup_eng(3)
with prog.context as q:
Fock(1) | q[1]
result = eng.run(prog)
state = result.state
nbar0, var_n0 = state.mean_photon(0)
nbar1, var_n1 = state.mean_photon(1)
nbar2, var_n2 = state.mean_photon(2)
assert np.allclose(nbar0, 0.0, atol=tol, rtol=0)
assert np.allclose(nbar1, 1.0, atol=tol, rtol=0)
assert np.allclose(nbar2, 0.0, atol=tol, rtol=0)
assert np.allclose(var_n0, 0.0, atol=tol, rtol=0)
assert np.allclose(var_n1, 0.0, atol=tol, rtol=0)
assert np.allclose(var_n2, 0.0, atol=tol, rtol=0)
def test_local(self):
"""Test a 1x2 lattice Bose-Hubbard model in local mode"""
self.eng.reset()
q = self.eng.register
with self.eng:
Sgate(0.1) | q[1]
Fock(2) | q[0]
BoseHubbardPropagation(self.H, self.t, self.k) | (q[0], q[2])
state = self.eng.run('fock', cutoff_dim=7, modes=[0, 2])
Hm = -self.J*np.sqrt(2)*np.array([[0, 1, 0], [1, 0, 1], [0, 1, 0]]) \
+ self.U*np.diag([1, 0, 1])
init_state = np.array([1, 0, 0])
exp = np.abs(np.dot(expm(-1j * self.t * Hm), init_state))**2
self.assertTrue(
np.allclose(state.fock_prob([2, 0]), exp[0], rtol=self.tol))
self.assertTrue(
np.allclose(state.fock_prob([1, 1]), exp[1], rtol=self.tol))
self.assertTrue(
np.allclose(state.fock_prob([0, 2]), exp[2], rtol=self.tol))
def test_1x2(self):
"""Test a 1x2 lattice Bose-Hubbard model"""
self.eng.reset()
q = self.eng.register
H = bose_hubbard(1, 2, self.J, self.U)
with self.eng:
Fock(2) | q[0]
BoseHubbardPropagation(H, self.t, self.k) | q
state = self.eng.run('fock', cutoff_dim=7)
Hm = -self.J*np.sqrt(2)*np.array([[0, 1, 0], [1, 0, 1], [0, 1, 0]]) \
+ self.U*np.diag([1, 0, 1])
init_state = np.array([1, 0, 0])
exp = np.abs(np.dot(expm(-1j * self.t * Hm), init_state))**2
self.assertTrue(
np.allclose(state.fock_prob([2, 0]), exp[0], rtol=self.tol))
self.assertTrue(
np.allclose(state.fock_prob([1, 1]), exp[1], rtol=self.tol))
self.assertTrue(
np.allclose(state.fock_prob([0, 2]), exp[2], rtol=self.tol))