Add qudit conjugation to QuditCodes

qldpc/codes.py

@@ -642,6 +642,18 @@ class QuditCode(AbstractCode):
     _exact_distance_x: int | None = None
     _exact_distance_z: int | None = None
 
+    def __init__(
+        self,
+        matrix: AbstractCode | npt.NDArray[np.int_] | Sequence[Sequence[int]],
+        field: int | None = None,
+        *,
+        conjugate: slice | Sequence[int] | None = (),
+    ) -> None:
+        """Construct a qudit code from a parity check matrix over a finite field."""
+        AbstractCode.__init__(self, matrix, field)
+        if conjugate:
+            self._matrix = self.field(QuditCode.conjugate(self._matrix, conjugate))
+
     def __str__(self) -> str:
         """Human-readable representation of this code."""
         name = type(self).__name__
@@ -2375,9 +2387,9 @@ def __init__(
 class FiveQubitCode(QuditCode):
     """Smallest quantum error-correcting code."""
 
-    def __init__(self) -> None:
+    def __init__(self, *, conjugate: slice | Sequence[int] | None = ()) -> None:
         code = QuditCode.from_stabilizers("X Z Z X I", "I X Z Z X", "X I X Z Z", "Z X I X Z")
-        QuditCode.__init__(self, code)
+        QuditCode.__init__(self, code, conjugate=conjugate)
 
 
 class SteaneCode(CSSCode):

qldpc/codes_test.py

@@ -607,5 +607,8 @@ def test_generalized_surface_codes(size: int = 3, field: int = 2) -> None:
 
 def test_small_codes() -> None:
     """Five-qubit and Steane codes."""
-    assert codes.FiveQubitCode().num_qubits == 5
     assert codes.SteaneCode().num_qubits == 7
+
+    code = codes.FiveQubitCode(conjugate=[1, 2])
+    assert code.num_qubits == 5
+    assert code.get_stabilizers()[0] == "X X X X I"