Fix CNOTDihedral class to support OpShape (qiskit-community#550)

qiskit/ignis/verification/randomized_benchmarking/dihedral.py

@@ -401,8 +401,7 @@ def __init__(self, data, validate=True):
             self.shift = elem.shift
 
         # Initialize BaseOperator
-        dims = self._num_qubits * (2,)
-        super().__init__(dims, dims)
+        super().__init__(num_qubits=self._num_qubits)
 
         # Validate the CNOTDihedral element
         if validate and not self.is_cnotdihedral():
@@ -591,7 +590,7 @@ def from_circuit(self, circuit):
             circuit = circuit.to_instruction()
 
         # Initialize an identity CNOTDihedral object
-        elem = CNOTDihedral(self.num_qubits)
+        elem = CNOTDihedral(self._num_qubits)
         append_circuit(elem, circuit)
         return elem
 
@@ -655,7 +654,7 @@ def dot(self, other, qargs=None):
         other.poly.weight_0 = 0  # set global phase
         return other
 
-    def _tensor_product(self, other, reverse=False):
+    def _tensor(self, other, reverse=False):
         """Returns the tensor product operator.
 
          Args:
@@ -719,7 +718,7 @@ def tensor(self, other):
              CNOTDihedral: the tensor product operator: self tensor other.
          """
 
-        return self._tensor_product(other, reverse=True)
+        return self._tensor(other, reverse=True)
 
     def expand(self, other):
         """Return the tensor product operator: other tensor self.
@@ -730,7 +729,7 @@ def expand(self, other):
              CNOTDihedral: the tensor product operator: other tensor other.
          """
 
-        return self._tensor_product(other, reverse=False)
+        return self._tensor(other, reverse=False)
 
     def adjoint(self):
         """Return the conjugate transpose of the CNOTDihedral element"""

test/rb/test_dihedral.py

@@ -20,7 +20,7 @@
 import numpy as np
 from qiskit.circuit import QuantumCircuit
 from qiskit.quantum_info.operators import Operator
-from qiskit.quantum_info.operators.pauli import Pauli
+from qiskit.quantum_info.operators import random
 
 import qiskit
 # Import the dihedral_utils functions
@@ -480,7 +480,7 @@ def test_init_from_pauli(self):
         nseed = 999
         for qubit_num in range(1, 5):
             for i in range(samples):
-                pauli = Pauli.random(qubit_num, seed=nseed + i)
+                pauli = random.random_pauli(qubit_num, seed=nseed + i)
                 elem = CNOTDihedral(pauli)
                 value = Operator(pauli)
                 target = Operator(elem)