Merge pull request #198 from qmatter-labs/erroneous_real

Removed the .real in expval, since PauliwordOp may have complex coeff…

Author: TimWeaving

symmer/operators/base.py

@@ -796,7 +796,7 @@ def expval(self, psi: "QuantumState") -> complex:
             complex: The expectation value.
         """
         if self.n_terms > psi.n_terms and psi.n_terms > 10:
-            return (psi.dagger * self * psi).real
+            return psi.dagger * self * psi
         else:
             if self.n_terms > 1:
                 @process.parallelize
@@ -807,7 +807,7 @@ def f(P, psi):
             else:
                 expvals = np.array(single_term_expval(self, psi))
 
-            return np.sum(expvals * self.coeff_vec).real
+            return np.sum(expvals * self.coeff_vec)
 
     def __mul__(self, 
             mul_obj: Union["PauliwordOp", "QuantumState", complex],

symmer/projection/qubit_subspace_manager.py

@@ -108,14 +108,14 @@ def build_subspace_objects(self) -> None:
             )
 
     def get_reduced_hamiltonian(self, 
-            n_qubits:int=None, aux_operator:PauliwordOp=None
+            n_qubits:int, aux_operator:PauliwordOp=None
         ) -> PauliwordOp:
         """ 
         Project the Hamiltonian in line with the desired qubit subspace techqniques
         and, in the case of ContextualSubspace, the desired number of qubits.
 
         Args:
-            n_qubits (int): Number of Qubits. By default, it is set to None.
+            n_qubits (int): Number of Qubits.
             aux_operator (PauliwordOp): Auxiliary operator. By default, it is set to None.
 
         Returns: