Add MajoranaOp class

.pylintdict

@@ -78,6 +78,7 @@ chkfile
 cholesky
 chuang
 ci
+classmethod
 clbit
 clbits
 clifford
@@ -300,6 +301,7 @@ kwargs
 kwds
 labelled
 langle
+lbl
 lbrace
 lda
 ldots
@@ -325,6 +327,7 @@ lvert
 lysine
 macos
 majorana
+majoranaop
 makefile
 matmul
 matplotlib
@@ -452,6 +455,7 @@ pxd
 py
 pydata
 pyquante
+pyright
 pyscf
 qarg
 qargs

qiskit_nature/second_q/operators/__init__.py

@@ -23,6 +23,7 @@
 
    ElectronicIntegrals
    FermionicOp
+   MajoranaOp
    BosonicOp
    SparseLabelOp
    SpinOp
@@ -44,6 +45,7 @@
 
 from .electronic_integrals import ElectronicIntegrals
 from .fermionic_op import FermionicOp
+from .majorana_op import MajoranaOp
 from .bosonic_op import BosonicOp
 from .spin_op import SpinOp
 from .vibrational_op import VibrationalOp
@@ -55,6 +57,7 @@
 __all__ = [
     "ElectronicIntegrals",
     "FermionicOp",
+    "MajoranaOp",
     "BosonicOp",
     "SpinOp",
     "VibrationalOp",

qiskit_nature/second_q/operators/fermionic_op.py

@@ -143,7 +143,6 @@ class FermionicOp(SparseLabelOp):
         However, a FermionicOp containing parameters does not support the following methods:
 
         - ``is_hermitian``
-        - ``to_matrix``
     """
 
     _OPERATION_REGEX = re.compile(r"([\+\-]_\d+\s)*[\+\-]_\d+")
@@ -460,7 +459,8 @@ def index_order(self) -> FermionicOp:
             }
         )
 
-    def _index_order(self, terms: list[tuple[str, int]], coeff: _TCoeff) -> tuple[str, _TCoeff]:
+    @classmethod
+    def _index_order(cls, terms: list[tuple[str, int]], coeff: _TCoeff) -> tuple[str, _TCoeff]:
         if not terms:
             return "", coeff
 
@@ -539,6 +539,7 @@ def simplify(self, atol: float | None = None) -> FermionicOp:
 
         data = defaultdict(complex)  # type: dict[str, _TCoeff]
         # TODO: use parallel_map to make this more efficient (?)
+        #       (if this is done, apply equally to MajoranaOp.simplify())
         for label, coeff in self.items():
             label, coeff = self._simplify_label(label, coeff)
             data[label] += coeff