Deprecate qiskit.extensions

docs/legacy_release_notes.rst

@@ -3619,7 +3619,7 @@ Bug Fixes
 .. releasenotes/notes/0.24/qasm2-exporter-rewrite-8993dd24f930b180.yaml @ b'4152009ee6d1bae8704f1e7b9ccc5727a53933bd'
 
 - The OpenQASM 2 exporter (:meth:`.QuantumCircuit.qasm`) will now handle multiple and nested
-  definitions of :class:`.UnitaryGate`.  See
+  definitions of :class:`~.library.UnitaryGate`.  See
   `#4623 <https://github.com/Qiskit/qiskit-terra/issues/4623>`__,
   `#6712 <https://github.com/Qiskit/qiskit-terra/issues/6712>`__,
   `#7772 <https://github.com/Qiskit/qiskit-terra/issues/7772>`__, and
@@ -5123,7 +5123,7 @@ New Features
   library gate classes have been updated to return more specific
   gate objects that result in a less lossy and more efficient output.
   For example, running :meth:`~.IGate.power` now returns an :class:`~.IGate`
-  instance instead of :class:`~.UnitaryGate` as was done previously.
+  instance instead of :class:`~.library.UnitaryGate` as was done previously.
 
   The full list of output types that have been improved are:
 
@@ -9148,7 +9148,7 @@ Bug Fixes
 .. releasenotes/notes/0.22/fix-qasm2-identity-as-unitary-aa2feeb05707a597.yaml @ b'618770367f7a5a3a22fd43ea9fcfb7f17393eb6a'
 
 - The OpenQASM 2 exporter (:meth:`.QuantumCircuit.qasm`) will now correctly
-  define the qubit parameters for :class:`.UnitaryGate` operations that do
+  define the qubit parameters for :class:`~.library.UnitaryGate` operations that do
   not affect all the qubits they are defined over.
   Fixed `#8224 <https://github.com/Qiskit/qiskit-terra/issues/8224>`__.
 
@@ -9372,7 +9372,7 @@ Known Issues
 .. releasenotes/notes/0.11/non-x86_ibm_cpu-493e51313ba222a6.yaml @ b'b7c4a322f8409fc2809b57b0701d1da6717c7efd'
 
 - When running on Linux s390x platforms (or other big endian platforms)
-  running circuits that contain :class:`~.UnitaryGate` operations will not
+  running circuits that contain :class:`~.library.UnitaryGate` operations will not
   work because of an endianess bug.
   See `#1506 <https://github.com/Qiskit/qiskit-aer/issues/1506>`__ for more
   details.
@@ -9692,7 +9692,7 @@ Bug Fixes
 .. releasenotes/notes/fix-evolvedop-to-instruction-c90c4f1aa6b4232a.yaml @ b'664747a66e2199a4b20abb9b7180cccb12c61a3f'
 
 - Fix :meth:`~.EvolvedOp.to_instruction` which previously tried to create a
-  :class:`~.UnitaryGate` without exponentiating the operator to evolve.
+  :class:`~.library.UnitaryGate` without exponentiating the operator to evolve.
   Since this operator is generally not unitary, this raised an error (and if
   the operator would have been unitary by chance, it would not have been the expected result).
 
@@ -10076,7 +10076,7 @@ New Features
   Shannon Decomposition of arbitrary unitaries. This functionality replaces
   the previous isometry-based approach in the default unitary synthesis
   transpiler pass as well as when adding unitaries to a circuit using a
-  :class:`.UnitaryGate`.
+  :class:`~.library.UnitaryGate`.
 
   The Quantum Shannon Decomposition uses about half the cnot gates as the
   isometry implementation when decomposing unitary matrices of greater than
@@ -10732,7 +10732,7 @@ Bug Fixes
 .. releasenotes/notes/fix-qasm2-identity-as-unitary-aa2feeb05707a597.yaml @ b'd7f932c8b242f69c5577afd5593bf36f839657f7'
 
 - The OpenQASM 2 exporter (:meth:`.QuantumCircuit.qasm`) will now correctly
-  define the qubit parameters for :class:`.UnitaryGate` operations that do
+  define the qubit parameters for :class:`~.library.UnitaryGate` operations that do
   not affect all the qubits they are defined over.
   Fixed `#8224 <https://github.com/Qiskit/qiskit-terra/issues/8224>`__.
 
@@ -10914,10 +10914,10 @@ Known Issues
 .. releasenotes/notes/ucr-gates-qpy-b8f6fb1e34fae258.yaml @ b'625b202a4dd0c223579dca44eec530b8a0813d76'
 
 - QPY deserialization with the :func:`.qpy.load` function of a directly
-  instantiated :class:`~.UCPauliRotGate` object in a circuit will fail
+  instantiated :class:`~.library.UCPauliRotGate` object in a circuit will fail
   because the rotation axis argument to the class isn't stored in a standard
   place. To workaround this you can instead use the subclasses:
-  :class:`~.UCRXGate`, :class:`~.UCRYGate`, or :class:`~.UCRZGate` (based on
+  :class:`~.library.UCRXGate`, :class:`~.library.UCRYGate`, or :class:`~.library.UCRZGate` (based on
   whether you're using a rotation axis of ``"X"``, ``"Y"``, or ``"Z"``
   respectively) which embeds the rotation axis in the class constructor and
   will work correctly in QPY.
@@ -11016,7 +11016,7 @@ Bug Fixes
 .. releasenotes/notes/ucr-gates-qpy-b8f6fb1e34fae258.yaml @ b'625b202a4dd0c223579dca44eec530b8a0813d76'
 
 - Fixed an issue with QPY deserialization via the :func:`.qpy.load` function
-  of the :class:`~.UCRXGate`, :class:`~.UCRYGate`, and :class:`~.UCRZGate`
+  of the :class:`~.library.UCRXGate`, :class:`~.library.UCRYGate`, and :class:`~.library.UCRZGate`
   classes.
   Previously, a QPY file that contained any of these gates would error
   when trying to load the file.

docs/migration_guides/opflow_migration.rst

@@ -1004,8 +1004,8 @@ delayed synthesis of the gates or efficient transpilation of the circuits, so th
     (for example, :class:`~qiskit.algorithms.time_evolvers.trotterization.TrotterQRTE`\).
 
     In a similar manner, the :class:`qiskit.opflow.evolutions.MatrixEvolution` class performs evolution by classical matrix exponentiation,
-    constructing a circuit with :class:`.UnitaryGate`\s or :class:`.HamiltonianGate`\s containing the exponentiation of the operator.
-    This class is no longer necessary, as the :class:`.HamiltonianGate`\s can be directly handled by the algorithms.
+    constructing a circuit with :class:`~.library.UnitaryGate`\s or :class:`~.library.HamiltonianGate`\s containing the exponentiation of the operator.
+    This class is no longer necessary, as the :class:`~.library.HamiltonianGate`\s can be directly handled by the algorithms.
 
 Trotterizations
 ---------------
@@ -1046,7 +1046,7 @@ Other Evolution Classes
      - No direct replacement. The workflow no longer requires a specific operator for evolutions.
 
    * - :class:`~qiskit.opflow.evolutions.MatrixEvolution`
-     - :class:`.HamiltonianGate`
+     - :class:`~.library.HamiltonianGate`
 
    * - :class:`~qiskit.opflow.evolutions.PauliTrotterEvolution`
      - :class:`.PauliEvolutionGate`

qiskit/__init__.py

@@ -66,9 +66,6 @@
 # user config
 from qiskit import user_config as _user_config
 
-# The qiskit.extensions.x imports needs to be placed here due to the
-# mechanism for adding gates dynamically.
-import qiskit.extensions
 import qiskit.circuit.measure
 import qiskit.circuit.reset
 

qiskit/assembler/disassemble.py

@@ -36,6 +36,20 @@
 # and a header dictionary.
 PulseModule = NewType("PulseModule", Tuple[List[pulse.Schedule], Dict[str, Any], Dict[str, Any]])
 
+# Prevent the disassembler from accessing deprecated circuit methods. This can happen for
+# gates where the name of the gate matches a circuit method (e.g. Isometry.name is "isometry")
+# and the circuit attribute is also QuantumCircuit.isometry
+_DEPRECATED_CIRCUIT_METHODS = {
+    "isometry",
+    "snapshot",
+    "ucrx",
+    "ucry",
+    "ucrz",
+    "squ",
+    "diagonal",
+    "hamiltonian",
+}
+
 
 def disassemble(qobj) -> Union[CircuitModule, PulseModule]:
     """Disassemble a qobj and return the circuits or pulse schedules, run_config, and user header.
@@ -165,16 +179,12 @@ def _experiments_to_circuits(qobj):
                     clbits.append(creg_dict[clbit_label[0]][clbit_label[1]])
             except Exception:  # pylint: disable=broad-except
                 pass
-            if hasattr(circuit, name):
+            # TODO remove the check that name is not in the deprecated circuit methods
+            # once the methods have been removed
+            if hasattr(circuit, name) and name not in _DEPRECATED_CIRCUIT_METHODS:
                 instr_method = getattr(circuit, name)
-                if i.name in ["snapshot"]:
-                    _inst = instr_method(
-                        i.label, snapshot_type=i.snapshot_type, qubits=qubits, params=params
-                    )
-                elif i.name == "initialize":
+                if i.name == "initialize":
                     _inst = instr_method(params, qubits)
-                elif i.name == "isometry":
-                    _inst = instr_method(*params, qubits, clbits)
                 elif i.name in ["mcx", "mcu1", "mcp"]:
                     _inst = instr_method(*params, qubits[:-1], qubits[-1], *clbits)
                 else:

qiskit/circuit/add_control.py

@@ -14,7 +14,7 @@
 from __future__ import annotations
 
 from qiskit.circuit.exceptions import CircuitError
-from qiskit.extensions import UnitaryGate
+from qiskit.circuit.library import UnitaryGate
 from . import ControlledGate, Gate, QuantumRegister, QuantumCircuit
 from ._utils import _ctrl_state_to_int
 

qiskit/circuit/gate.py

@@ -68,13 +68,15 @@ def power(self, exponent: float):
             exponent (float): Gate^exponent
 
         Returns:
-            qiskit.extensions.UnitaryGate: To which `to_matrix` is self.to_matrix^exponent.
+            .library.UnitaryGate: To which `to_matrix` is self.to_matrix^exponent.
 
         Raises:
             CircuitError: If Gate is not unitary
         """
-        from qiskit.quantum_info.operators import Operator  # pylint: disable=cyclic-import
-        from qiskit.extensions.unitary import UnitaryGate  # pylint: disable=cyclic-import
+        # pylint: disable=cyclic-import
+        from qiskit.quantum_info.operators import Operator
+        from qiskit.circuit.library.generalized_gates.unitary import UnitaryGate
+
         from scipy.linalg import schur
 
         # Should be diagonalized because it's a unitary.

qiskit/circuit/library/__init__.py

@@ -181,6 +181,7 @@
    :template: autosummary/class_no_inherited_members.rst
 
    Diagonal
+   DiagonalGate
    MCMT
    MCMTVChain
    Permutation
@@ -198,6 +199,13 @@
    RVGate
    PauliGate
    LinearFunction
+   Isometry
+   UnitaryGate
+   UCGate
+   UCPauliRotGate
+   UCRXGate
+   UCRYGate
+   UCRZGate
 
 Boolean Logic Circuits
 ======================
@@ -324,6 +332,7 @@
    PhaseOracle
    EvolvedOperatorAnsatz
    PauliEvolutionGate
+   HamiltonianGate
 
 
 N-local circuits
@@ -360,6 +369,7 @@
    ZFeatureMap
    ZZFeatureMap
    StatePreparation
+   Initialize
 
 Template circuits
 =================
@@ -492,6 +502,7 @@
 from .blueprintcircuit import BlueprintCircuit
 from .generalized_gates import (
     Diagonal,
+    DiagonalGate,
     MCMT,
     MCMTVChain,
     Permutation,
@@ -505,8 +516,16 @@
     RVGate,
     PauliGate,
     LinearFunction,
+    Isometry,
+    UnitaryGate,
+    UCGate,
+    UCPauliRotGate,
+    UCRXGate,
+    UCRYGate,
+    UCRZGate,
 )
 from .pauli_evolution import PauliEvolutionGate
+from .hamiltonian_gate import HamiltonianGate
 from .boolean_logic import (
     AND,
     OR,
@@ -542,7 +561,13 @@
     ExcitationPreserving,
     QAOAAnsatz,
 )
-from .data_preparation import PauliFeatureMap, ZFeatureMap, ZZFeatureMap, StatePreparation
+from .data_preparation import (
+    PauliFeatureMap,
+    ZFeatureMap,
+    ZZFeatureMap,
+    StatePreparation,
+    Initialize,
+)
 from .quantum_volume import QuantumVolume
 from .fourier_checking import FourierChecking
 from .graph_state import GraphState

qiskit/circuit/library/arithmetic/exact_reciprocal.py

@@ -14,7 +14,7 @@
 from math import isclose
 import numpy as np
 from qiskit.circuit import QuantumCircuit, QuantumRegister
-from qiskit.extensions.quantum_initializer import UCRYGate
+from qiskit.circuit.library.generalized_gates import UCRYGate
 
 
 class ExactReciprocal(QuantumCircuit):

qiskit/circuit/library/data_preparation/__init__.py

@@ -42,5 +42,6 @@
 from .z_feature_map import ZFeatureMap
 from .zz_feature_map import ZZFeatureMap
 from .state_preparation import StatePreparation
+from .initializer import Initialize
 
-__all__ = ["PauliFeatureMap", "ZFeatureMap", "ZZFeatureMap", "StatePreparation"]
+__all__ = ["PauliFeatureMap", "ZFeatureMap", "ZZFeatureMap", "StatePreparation", "Initialize"]

qiskit/circuit/library/data_preparation/initializer.py

@@ -0,0 +1,96 @@
+# This code is part of Qiskit.
+#
+# (C) Copyright IBM 2017.
+#
+# 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.
+
+"""
+Initialize qubit registers to desired arbitrary state.
+"""
+
+from __future__ import annotations
+from collections.abc import Sequence
+import typing
+
+from qiskit.circuit.quantumcircuit import QuantumCircuit
+from qiskit.circuit.quantumregister import QuantumRegister
+from qiskit.circuit.instruction import Instruction
+from .state_preparation import StatePreparation
+
+if typing.TYPE_CHECKING:
+    from qiskit.quantum_info.states.statevector import Statevector
+
+_EPS = 1e-10  # global variable used to chop very small numbers to zero
+
+
+class Initialize(Instruction):
+    """Complex amplitude initialization.
+
+    Class that initializes some flexible collection of qubit registers, implemented by calling
+    the :class:`~.library.StatePreparation` class.
+    Note that ``Initialize`` is an :class:`~.circuit.Instruction` and not a :class:`.Gate` since it
+    contains a reset instruction, which is not unitary.
+    """
+
+    def __init__(
+        self,
+        params: Statevector | Sequence[complex] | str | int,
+        num_qubits: int | None = None,
+        normalize: bool = False,
+    ) -> None:
+        r"""
+        Args:
+            params: The state to initialize to, can be either of the following.
+
+                * Statevector or vector of complex amplitudes to initialize to.
+                * Labels of basis states of the Pauli eigenstates Z, X, Y. See
+                  :meth:`.Statevector.from_label`. Notice the order of the labels is reversed with
+                  respect to the qubit index to be applied to. Example label '01' initializes the
+                  qubit zero to :math:`|1\rangle` and the qubit one to :math:`|0\rangle`.
+                * An integer that is used as a bitmap indicating which qubits to initialize to
+                  :math:`|1\rangle`. Example: setting params to 5 would initialize qubit 0 and qubit
+                  2 to :math:`|1\rangle` and qubit 1 to :math:`|0\rangle`.
+
+            num_qubits: This parameter is only used if params is an int. Indicates the total
+                number of qubits in the `initialize` call. Example: `initialize` covers 5 qubits
+                and params is 3. This allows qubits 0 and 1 to be initialized to :math:`|1\rangle`
+                and the remaining 3 qubits to be initialized to :math:`|0\rangle`.
+            normalize: Whether to normalize an input array to a unit vector.
+        """
+        self._stateprep = StatePreparation(params, num_qubits, normalize=normalize)
+
+        super().__init__("initialize", self._stateprep.num_qubits, 0, self._stateprep.params)
+
+    def _define(self):
+        q = QuantumRegister(self.num_qubits, "q")
+        initialize_circuit = QuantumCircuit(q, name="init_def")
+        initialize_circuit.reset(q)
+        initialize_circuit.append(self._stateprep, q)
+        self.definition = initialize_circuit
+
+    def gates_to_uncompute(self) -> QuantumCircuit:
+        """Call to create a circuit with gates that take the desired vector to zero.
+
+        Returns:
+            Circuit to take ``self.params`` vector to :math:`|{00\\ldots0}\\rangle`
+        """
+        return self._stateprep._gates_to_uncompute()
+
+    @property
+    def params(self):
+        """Return initialize params."""
+        return self._stateprep.params
+
+    @params.setter
+    def params(self, parameters: Statevector | Sequence[complex] | str | int) -> None:
+        """Set initialize params."""
+        self._stateprep.params = parameters
+
+    def broadcast_arguments(self, qargs, cargs):
+        return self._stateprep.broadcast_arguments(qargs, cargs)

qiskit/circuit/library/data_preparation/state_preparation.py

@@ -17,15 +17,16 @@
 import numpy as np
 
 from qiskit.exceptions import QiskitError
-from qiskit.circuit import QuantumCircuit, QuantumRegister, Qubit
+from qiskit.circuit.quantumcircuit import QuantumCircuit
+from qiskit.circuit.quantumregister import QuantumRegister, Qubit
 from qiskit.circuit.gate import Gate
 from qiskit.circuit.library.standard_gates.x import CXGate, XGate
 from qiskit.circuit.library.standard_gates.h import HGate
 from qiskit.circuit.library.standard_gates.s import SGate, SdgGate
 from qiskit.circuit.library.standard_gates.ry import RYGate
 from qiskit.circuit.library.standard_gates.rz import RZGate
 from qiskit.circuit.exceptions import CircuitError
-from qiskit.quantum_info import Statevector
+from qiskit.quantum_info.states.statevector import Statevector  # pylint: disable=cyclic-import
 
 _EPS = 1e-10  # global variable used to chop very small numbers to zero