Small fixes docs (#11459)

* Remove duplicated skip_unentangled_qubits parameter from docstring

* Add missing backslashes in several docstrings

* Add type hints to fix docstring for LinearFunction

* Add :math: to ZZFeatureMap docstring equations

qiskit/circuit/library/data_preparation/zz_feature_map.py

@@ -18,7 +18,7 @@
 
 
 class ZZFeatureMap(PauliFeatureMap):
-    """Second-order Pauli-Z evolution circuit.
+    r"""Second-order Pauli-Z evolution circuit.
 
     For 3 qubits and 1 repetition and linear entanglement the circuit is represented by:
 
@@ -32,8 +32,8 @@ class ZZFeatureMap(PauliFeatureMap):
         ┤ H ├┤ U1(2.0*φ(x[2])) ├──────────────────────────────────┤ X ├┤ U1(2.0*φ(x[1],x[2])) ├┤ X ├
         └───┘└─────────────────┘                                  └───┘└──────────────────────┘└───┘
 
-    where ``φ`` is a classical non-linear function, which defaults to ``φ(x) = x`` if and
-    ``φ(x,y) = (pi - x)(pi - y)``.
+    where :math:`\varphi` is a classical non-linear function, which defaults to :math:`\varphi(x) = x`
+    if and :math:`\varphi(x,y) = (\pi - x)(\pi - y)`.
 
     Examples:
 

qiskit/circuit/library/generalized_gates/linear_function.py

@@ -19,6 +19,9 @@
 from qiskit.synthesis.linear import check_invertible_binary_matrix
 from qiskit.circuit.library.generalized_gates.permutation import PermutationGate
 
+# pylint: disable=cyclic-import
+from qiskit.quantum_info import Clifford
+
 
 class LinearFunction(Gate):
     r"""A linear reversible circuit on n qubits.
@@ -62,16 +65,23 @@ class LinearFunction(Gate):
     `Online at umich.edu. <https://web.eecs.umich.edu/~imarkov/pubs/jour/qic08-cnot.pdf>`_
     """
 
-    def __init__(self, linear, validate_input=False):
+    def __init__(
+        self,
+        linear: list[list]
+        | np.ndarray[bool]
+        | QuantumCircuit
+        | LinearFunction
+        | PermutationGate
+        | Clifford,
+        validate_input: bool = False,
+    ) -> None:
         """Create a new linear function.
 
         Args:
-            linear (list[list] or ndarray[bool] or QuantumCircuit or LinearFunction
-                or PermutationGate or Clifford): data from which a linear function
-                can be constructed. It can be either a nxn matrix (describing the
-                linear transformation), a permutation (which is a special case of
-                a linear function), another linear function, a clifford (when it
-                corresponds to a linear function), or a quantum circuit composed of
+            linear: data from which a linear function can be constructed. It can be either a
+                nxn matrix (describing the linear transformation), a permutation (which is a
+                special case of a linear function), another linear function, a clifford (when
+                it corresponds to a linear function), or a quantum circuit composed of
                 linear gates (CX and SWAP) and other objects described above, including
                 nested subcircuits.
 
@@ -86,9 +96,6 @@ def __init__(self, linear, validate_input=False):
                 not correspond to a linear function).
         """
 
-        # pylint: disable=cyclic-import
-        from qiskit.quantum_info import Clifford
-
         original_circuit = None
 
         if isinstance(linear, (list, np.ndarray)):

qiskit/circuit/library/n_local/excitation_preserving.py

@@ -116,9 +116,6 @@ def __init__(
                 See the Examples section of :class:`~qiskit.circuit.library.TwoLocal` for more
                 detail.
             initial_state: A `QuantumCircuit` object to prepend to the circuit.
-            skip_unentangled_qubits: If True, the single qubit gates are only applied to qubits
-                that are entangled with another qubit. If False, the single qubit gates are applied
-                to each qubit in the Ansatz. Defaults to False.
             skip_unentangled_qubits: If True, the single qubit gates are only applied to qubits
                 that are entangled with another qubit. If False, the single qubit gates are applied
                 to each qubit in the Ansatz. Defaults to False.

qiskit/circuit/library/n_local/real_amplitudes.py

@@ -144,9 +144,6 @@ def __init__(
                 See the Examples section of :class:`~qiskit.circuit.library.TwoLocal` for more
                 detail.
             initial_state: A `QuantumCircuit` object to prepend to the circuit.
-            skip_unentangled_qubits: If True, the single qubit gates are only applied to qubits
-                that are entangled with another qubit. If False, the single qubit gates are applied
-                to each qubit in the Ansatz. Defaults to False.
             skip_unentangled_qubits: If True, the single qubit gates are only applied to qubits
                 that are entangled with another qubit. If False, the single qubit gates are applied
                 to each qubit in the Ansatz. Defaults to False.

qiskit/circuit/library/phase_estimation.py

@@ -24,7 +24,7 @@ class PhaseEstimation(QuantumCircuit):
 
     In the Quantum Phase Estimation (QPE) algorithm [1, 2, 3], the Phase Estimation circuit is used
     to estimate the phase :math:`\phi` of an eigenvalue :math:`e^{2\pi i\phi}` of a unitary operator
-    :math:`U`, provided with the corresponding eigenstate :math:`|psi\rangle`.
+    :math:`U`, provided with the corresponding eigenstate :math:`|\psi\rangle`.
     That is
 
     .. math::

qiskit/circuit/library/standard_gates/sx.py

@@ -139,7 +139,7 @@ class SXdgGate(SingletonGate):
                         1 & i \\
                         i & 1
                       \end{pmatrix}
-                    = e^{-i pi/4} \sqrt{X}^{\dagger}
+                    = e^{-i \pi/4} \sqrt{X}^{\dagger}
 
     """
 

qiskit/circuit/library/standard_gates/xx_minus_yy.py

@@ -65,8 +65,8 @@ class XXMinusYYGate(Gate):
         In Qiskit's convention, higher qubit indices are more significant
         (little endian convention). In the above example we apply the gate
         on (q_0, q_1) which results in adding the (optional) phase defined
-        by :math:`beta` on q_1. Instead, if we apply it on (q_1, q_0), the
-        phase is added on q_0. If :math:`beta` is set to its default value
+        by :math:`\beta` on q_1. Instead, if we apply it on (q_1, q_0), the
+        phase is added on q_0. If :math:`\beta` is set to its default value
         of :math:`0`, the gate is equivalent in big and little endian.
 
         .. parsed-literal::

qiskit/circuit/library/standard_gates/xx_plus_yy.py

@@ -56,8 +56,8 @@ class XXPlusYYGate(Gate):
         In Qiskit's convention, higher qubit indices are more significant
         (little endian convention). In the above example we apply the gate
         on (q_0, q_1) which results in adding the (optional) phase defined
-        by :math:`beta` on q_0. Instead, if we apply it on (q_1, q_0), the
-        phase is added on q_1. If :math:`beta` is set to its default value
+        by :math:`\beta` on q_0. Instead, if we apply it on (q_1, q_0), the
+        phase is added on q_1. If :math:`\beta` is set to its default value
         of :math:`0`, the gate is equivalent in big and little endian.
 
         .. parsed-literal::