Add Ternary Tree Mapper

.pylintdict

@@ -78,6 +78,7 @@ chkfile
 cholesky
 chuang
 ci
+classmethod
 clbit
 clbits
 clifford
@@ -280,6 +281,7 @@ jcf
 jcp
 jernigan
 ji
+jiang
 jk
 jl
 jordan
@@ -289,6 +291,7 @@ json
 jupyter
 jw
 kagome
+kalev
 kanav
 ket
 kitaev
@@ -301,6 +304,7 @@ kwargs
 kwds
 labelled
 langle
+lbl
 lbrace
 lda
 ldots
@@ -326,6 +330,7 @@ lvert
 lysine
 macos
 majorana
+majoranaop
 makefile
 matmul
 matplotlib
@@ -357,6 +362,7 @@ moller
 molssi
 morse
 mpl
+mruczkiewicz
 mul
 multi
 multigraph
@@ -377,6 +383,7 @@ neq
 networkx
 neuropeptide
 neutron
+neven
 nicholas
 nielsen
 nisq
@@ -453,6 +460,7 @@ pxd
 py
 pydata
 pyquante
+pyright
 pyscf
 qarg
 qargs
@@ -658,11 +666,16 @@ xcfun
 xdata
 xy
 xyz
+xzy
 ydata
 yx
+yxz
 yy
+yzx
 zeitschrift
 zi
 zmatrix
 zsh
+zxy
+zyx
 zz

qiskit_nature/second_q/mappers/__init__.py

@@ -1,6 +1,6 @@
 # This code is part of a Qiskit project.
 #
-# (C) Copyright IBM 2022, 2023.
+# (C) Copyright IBM 2022, 2024.
 #
 # This code is licensed under the Apache License, Version 2.0. You may
 # obtain a copy of this license in the LICENSE.txt file in the root directory
@@ -25,6 +25,7 @@
    :nosignatures:
 
    QubitMapper
+   ModeBasedMapper
 
 FermionicOp Mappers
 +++++++++++++++++++
@@ -37,6 +38,14 @@
    BravyiKitaevSuperFastMapper
    JordanWignerMapper
    ParityMapper
+   TernaryTreeMapper
+
+**Note:** :class:`~qiskit_nature.second_q.mappers.TernaryTreeMapper` maps
+:class:`~qiskit_nature.second_q.operators.MajoranaOp` to
+:class:`~qiskit.quantum_info.SparsePauliOp`. In order to use it on a
+:class:`~qiskit_nature.second_q.operators.FermionicOp`, convert to a
+:class:`~qiskit_nature.second_q.operators.MajoranaOp` first using
+:code:`MajoranaOp.from_fermionic_op()`.
 
 **Interleaved Qubit-Ordering:** If you want to generate qubit operators where the alpha-spin and
 beta-spin components are mapped to the qubit register in an interleaved (rather than the default
@@ -96,11 +105,13 @@
 from .bravyi_kitaev_mapper import BravyiKitaevMapper
 from .jordan_wigner_mapper import JordanWignerMapper
 from .parity_mapper import ParityMapper
+from .ternary_tree_mapper import TernaryTreeMapper
 from .linear_mapper import LinearMapper
 from .bosonic_linear_mapper import BosonicLinearMapper
 from .logarithmic_mapper import LogarithmicMapper
 from .direct_mapper import DirectMapper
 from .qubit_mapper import QubitMapper
+from .mode_based_mapper import ModeBasedMapper
 from .interleaved_qubit_mapper import InterleavedQubitMapper
 from .tapered_qubit_mapper import TaperedQubitMapper
 
@@ -110,10 +121,12 @@
     "DirectMapper",
     "JordanWignerMapper",
     "ParityMapper",
+    "TernaryTreeMapper",
     "LinearMapper",
     "BosonicLinearMapper",
     "LogarithmicMapper",
     "QubitMapper",
     "InterleavedQubitMapper",
     "TaperedQubitMapper",
+    "ModeBasedMapper",
 ]

qiskit_nature/second_q/mappers/bosonic_linear_mapper.py

@@ -1,6 +1,6 @@
 # This code is part of a Qiskit project.
 #
-# (C) Copyright IBM 2023.
+# (C) Copyright IBM 2023, 2024.
 #
 # This code is licensed under the Apache License, Version 2.0. You may
 # obtain a copy of this license in the LICENSE.txt file in the root directory
@@ -29,7 +29,7 @@ class BosonicLinearMapper(BosonicMapper):
     """The Linear boson-to-qubit mapping.
 
     This mapper generates a linear encoding of the Bosonic operator :math:`b_k^\\dagger, b_k` to qubit
-    operators (linear combinations of pauli strings).
+    operators (linear combinations of Pauli strings).
     In this linear encoding each bosonic mode is represented via :math:`n_k^{max} + 1` qubits, where
     :math:`n_k^{max}` is the max occupation of the mode (meaning the number of states used in the
     expansion of the mode, or equivalently the state at which the maximum excitation can take place).

qiskit_nature/second_q/mappers/bosonic_mapper.py

@@ -1,6 +1,6 @@
 # This code is part of a Qiskit project.
 #
-# (C) Copyright IBM 2023.
+# (C) Copyright IBM 2023, 2024.
 #
 # This code is licensed under the Apache License, Version 2.0. You may
 # obtain a copy of this license in the LICENSE.txt file in the root directory

qiskit_nature/second_q/mappers/bravyi_kitaev_mapper.py

@@ -21,15 +21,18 @@
 from qiskit.quantum_info.operators import Pauli
 
 from .fermionic_mapper import FermionicMapper
+from .mode_based_mapper import ModeBasedMapper, PauliType
 
 
-class BravyiKitaevMapper(FermionicMapper):
+class BravyiKitaevMapper(FermionicMapper, ModeBasedMapper):
     """The Bravyi-Kitaev fermion-to-qubit mapping."""
 
-    @classmethod
+    def pauli_table(self, register_length: int) -> list[tuple[PauliType, PauliType]]:
+        return self._pauli_table(register_length)
+
+    @staticmethod
     @lru_cache(maxsize=32)
-    def pauli_table(cls, register_length: int) -> list[tuple[Pauli, Pauli]]:
-        # pylint: disable=unused-argument
+    def _pauli_table(register_length: int) -> list[tuple[PauliType, PauliType]]:
         def parity_set(j, n):
             """
             Computes the parity set of the j-th orbital in n modes.

qiskit_nature/second_q/mappers/direct_mapper.py

@@ -21,19 +21,22 @@
 from qiskit.quantum_info.operators import Pauli
 
 from .vibrational_mapper import VibrationalMapper
+from .mode_based_mapper import ModeBasedMapper, PauliType
 
 
-class DirectMapper(VibrationalMapper):
+class DirectMapper(VibrationalMapper, ModeBasedMapper):
     """The Direct mapper.
 
     This mapper maps a :class:`~.VibrationalOp` to a qubit operator. In doing so, each modal of the
     ``VibrationalOp`` gets mapped to a single qubit.
     """
 
-    @classmethod
+    def pauli_table(self, register_length: int) -> list[tuple[PauliType, PauliType]]:
+        return self._pauli_table(register_length)
+
+    @staticmethod
     @lru_cache(maxsize=32)
-    def pauli_table(cls, register_length: int) -> list[tuple[Pauli, Pauli]]:
-        # pylint: disable=unused-argument
+    def _pauli_table(register_length: int) -> list[tuple[PauliType, PauliType]]:
         pauli_table = []
 
         for i in range(register_length):

qiskit_nature/second_q/mappers/jordan_wigner_mapper.py

@@ -21,15 +21,18 @@
 from qiskit.quantum_info.operators import Pauli
 
 from .fermionic_mapper import FermionicMapper
+from .mode_based_mapper import ModeBasedMapper, PauliType
 
 
-class JordanWignerMapper(FermionicMapper):
+class JordanWignerMapper(FermionicMapper, ModeBasedMapper):
     """The Jordan-Wigner fermion-to-qubit mapping."""
 
-    @classmethod
+    def pauli_table(self, register_length: int) -> list[tuple[PauliType, PauliType]]:
+        return self._pauli_table(register_length)
+
+    @staticmethod
     @lru_cache(maxsize=32)
-    def pauli_table(cls, register_length: int) -> list[tuple[Pauli, Pauli]]:
-        # pylint: disable=unused-argument
+    def _pauli_table(register_length: int) -> list[tuple[PauliType, PauliType]]:
         pauli_table = []
 
         for i in range(register_length):

qiskit_nature/second_q/mappers/logarithmic_mapper.py

@@ -143,7 +143,7 @@ def _logarithmic_encoding(
             op.chop()
             spin_op_encoding.append(op)
 
-        return tuple(spin_op_encoding)
+        return (spin_op_encoding[0], spin_op_encoding[1], spin_op_encoding[2], spin_op_encoding[3])
 
     def _embed_matrix(
         self,

qiskit_nature/second_q/mappers/majorana_mapper.py

@@ -0,0 +1,33 @@
+# This code is part of a Qiskit project.
+#
+# (C) Copyright IBM 2024.
+#
+# This code is licensed under the Apache License, Version 2.0. You may
+# obtain a copy of this license in the LICENSE.txt file in the root directory
+# of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
+#
+# Any modifications or derivative works of this code must retain this
+# copyright notice, and modified files need to carry a notice indicating
+# that they have been altered from the originals.
+
+"""Majorana Mapper."""
+
+from __future__ import annotations
+
+from qiskit.quantum_info import SparsePauliOp
+
+from qiskit_nature.second_q.operators import MajoranaOp
+
+from .qubit_mapper import ListOrDictType, QubitMapper
+
+
+class MajoranaMapper(QubitMapper):
+    """Mapper of Majorana Operator to Qubit Operator"""
+
+    def map(
+        self,
+        second_q_ops: MajoranaOp | ListOrDictType[MajoranaOp],
+        *,
+        register_length: int | None = None,
+    ) -> SparsePauliOp | ListOrDictType[SparsePauliOp]:
+        return super().map(second_q_ops, register_length=register_length)