support gate powering with ** (#9030)

* support gate powering with ** * separate test Co-authored-by: Jake Lishman <[email protected]> Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>
Qiskit · Jan 11, 2023 · 7ed5de3 · 7ed5de3
1 parent 804665b
commit 7ed5de3
Show file tree

Hide file tree

Showing 3 changed files with 19 additions and 0 deletions.
diff --git a/qiskit/circuit/gate.py b/qiskit/circuit/gate.py
@@ -87,6 +87,9 @@ def power(self, exponent: float):
         unitary_power = unitary @ np.diag(decomposition_power) @ unitary.conj().T
         return UnitaryGate(unitary_power, label=f"{self.name}^{exponent}")
 
+    def __pow__(self, exponent: float) -> "Gate":
+        return self.power(exponent)
+
     def _return_repeat(self, exponent: float) -> "Gate":
         return Gate(name=f"{self.name}*{exponent}", num_qubits=self.num_qubits, params=self.params)
 

diff --git a/releasenotes/notes/gate-power-6f97f9db5c36def3.yaml b/releasenotes/notes/gate-power-6f97f9db5c36def3.yaml
@@ -0,0 +1,5 @@
+---
+features:
+  - |
+    Powering gates using ``**`` is now supported.
+    Example: ``sqrt_x = XGate() ** 0.5``
diff --git a/test/python/circuit/test_gate_power.py b/test/python/circuit/test_gate_power.py
@@ -211,6 +211,17 @@ def test_invariant2(self, n):
         self.assertEqual(result, expected)
 
 
+@ddt
+class TestGatePow(QiskitTestCase):
+    """Test gate __pow__ method."""
+
+    @data(2, 3, 4, 5)
+    def test_gate_pow(self, degree):
+        """Test gate __pow__ method."""
+        self.assertEqual(SGate() ** (1 / degree), SGate().power(1 / degree))
+        self.assertEqual(CXGate() ** (1 / degree), CXGate().power(1 / degree))
+
+
 @ddt
 class TestEfficientGatePowering(QiskitTestCase):
     """Test gate powering is efficient where expected."""