optimize trotter time evolution

Author: liwt31

tencirchem/dynamic/time_derivative.py

@@ -73,14 +73,17 @@ def get_circuit(ham_terms, spin_basis, n_layers, init_state, params, param_ids=N
  return c
 
 
-def one_trotter_step(ham_terms, spin_basis, init_state, dt):
+def one_trotter_step(ham_terms, spin_basis, init_state, dt, inplace=False):
  """
  one step first order trotter decompostion
  """
  ansatz_op_list = construct_ansatz_op(ham_terms, spin_basis)
 
  if isinstance(init_state, tc.Circuit):
- c = tc.Circuit.from_qir(init_state.to_qir(), circuit_params=init_state.circuit_param)
+ if inplace:
+ c = init_state
+ else:
+ c = tc.Circuit.from_qir(init_state.to_qir(), circuit_params=init_state.circuit_param)
  else:
  c = tc.Circuit(len(spin_basis), inputs=init_state)
 

tencirchem/dynamic/time_evolution.py

@@ -85,8 +85,8 @@ def __init__(
  self.ansatz = get_ansatz(self.model.ham_terms, self.model.basis, self.n_layers, self.init_circuit)
  self.jacobian_func = get_jacobian_func(self.ansatz)
 
- self.current_circuit = self.init_circuit
  # setup runtime components
+ self.current_circuit = self.init_circuit
  self.eps = eps
  self.include_phase = False
  if ivp_config is None:
@@ -152,8 +152,9 @@ def kernel(self, tau, algo="vqd"):
  self.scipy_sol_list.append(scipy_sol)
  else:
  assert algo == "trotter"
- self.current_circuit = one_trotter_step(self.model.ham_terms, self.model.basis, self.current_circuit, tau)
- state = self.current_circuit.state()
+ self.current_circuit = one_trotter_step(self.model.ham_terms, self.model.basis, self.current_circuit, tau, inplace=True)
+ shortcut = one_trotter_step(self.model.ham_terms, self.model.basis, self.state, tau)
+ state = shortcut.state()
 
  time1 = time.time()
  self.t_list.append(self.t + tau)

tests/static/test_hea.py

@@ -29,7 +29,10 @@ def test_hea(engine, backend_str, grad, reset_backend):
  hea = HEA.ry(uccsd.int1e, uccsd.int2e, uccsd.n_elec, uccsd.e_core, 3, engine=engine)
  hea.grad = grad
  e = hea.kernel()
- np.testing.assert_allclose(e, uccsd.e_fci, atol=0.1)
+ atol = 0.1
+ if engine == "tensornetwork-noise&shot" and grad == "free":
+ atol *= 2
+ np.testing.assert_allclose(e, uccsd.e_fci, atol=atol)
 
 
 def test_qiskit_circuit():