def test_ToricCode(Lx=1, Ly=2):
with warnings.catch_warnings():
warnings.simplefilter('ignore')
model_params = {'Lx': Lx, 'Ly': Ly}
M = ToricCode(model_params)
psi = MPS.from_product_state(M.lat.mps_sites(), [0] * M.lat.N_sites,
bc='infinite')
dmrg_params = {
'mixer': True,
'trunc_params': {
'chi_max': 10,
'svd_min': 1.e-10
},
'max_E_err': 1.e-10,
'N_sweeps_check': 4,
'verbose': 1
}
result = dmrg.run(psi, M, dmrg_params)
E = result['E']
print("E =", E)
psi.canonical_form()
# energy per "cell"=2 -> energy per site in the dual lattice = 1
assert abs(E - (-1.)) < dmrg_params['max_E_err']
print("chi=", psi.chi)
if Ly == 2:
assert tuple(psi.chi[:4]) == (2, 4, 4, 4)
assert abs(
psi.entanglement_entropy(bonds=[0])[0] - np.log(2) *
(Ly - 1)) < 1.e-5
def test_ToricCode(Lx=1, Ly=2):
model_params = {'Lx': Lx, 'Ly': Ly, 'bc_MPS': 'infinite'}
M = ToricCode(model_params)
psi = MPS.from_product_state(M.lat.mps_sites(), [0] * M.lat.N_sites, bc='infinite')
dmrg_params = {
'mixer': True,
'trunc_params': {
'chi_max': 10,
'svd_min': 1.e-10
},
'P_tol_to_trunc': None, # avoid warning about unused "P_tol" lanczos
'max_E_err': 1.e-10,
'N_sweeps_check': 4,
}
result = dmrg.run(psi, M, dmrg_params)
E = result['E']
print("E =", E)
psi.canonical_form()
# energy per "cell"=2 -> energy per site in the dual lattice = 1
assert abs(E - (-1.)) < dmrg_params['max_E_err']
print("chi=", psi.chi)
if Ly == 2:
assert tuple(psi.chi[:4]) == (2, 2, 2, 2)
assert abs(psi.entanglement_entropy(bonds=[0])[0] - np.log(2) * (Ly - 1)) < 1.e-5