Some doc formatting and link, mostly on quantumcircuit.py file

qiskit/algorithms/optimizers/qnspsa.py

@@ -277,7 +277,7 @@ def get_fidelity(
             F(\theta, \phi) = \big|\langle 0 | U^\dagger(\theta) U(\phi) |0\rangle  \big|^2.
 
         The output of this function can be used as input for the ``fidelity`` to the
-        :class:~`qiskit.algorithms.optimizers.QNSPSA` optimizer.
+        :class:`~.QNSPSA` optimizer.
 
         Args:
             circuit: The circuit preparing the parameterized ansatz.

qiskit/circuit/controlflow/for_loop.py

@@ -142,7 +142,7 @@ class ForLoopContext:
         from qiskit import QuantumCircuit
         qc = QuantumCircuit(2, 1)
 
-        with qc.for_loop(None, range(5)) as i:
+        with qc.for_loop(range(5)) as i:
             qc.rx(i * math.pi/4, 0)
             qc.cx(0, 1)
             qc.measure(0, 0)

qiskit/circuit/instruction.py

@@ -421,8 +421,8 @@ def copy(self, name=None):
             if None then the name stays the same.
 
         Returns:
-          qiskit.circuit.Instruction: a copy of the current instruction, with the name
-            updated if it was provided
+          qiskit.circuit.Instruction: a copy of the current instruction, with the name updated if it
+          was provided
         """
         cpy = self.__deepcopy__()
 

qiskit/circuit/quantumcircuit.py

@@ -130,11 +130,11 @@ class QuantumCircuit:
     A circuit is a list of instructions bound to some registers.
 
     Args:
-        regs (list(:class:`Register`) or list(``int``) or list(list(:class:`Bit`))): The
+        regs (list(:class:`.Register`) or list(``int``) or list(list(:class:`.Bit`))): The
             registers to be included in the circuit.
 
-            * If a list of :class:`Register` objects, represents the :class:`QuantumRegister`
-              and/or :class:`ClassicalRegister` objects to include in the circuit.
+            * If a list of :class:`.Register` objects, represents the :class:`.QuantumRegister`
+              and/or :class:`.ClassicalRegister` objects to include in the circuit.
 
               For example:
 
@@ -151,8 +151,8 @@ class QuantumCircuit:
                 * ``QuantumCircuit(4) # A QuantumCircuit with 4 qubits``
                 * ``QuantumCircuit(4, 3) # A QuantumCircuit with 4 qubits and 3 classical bits``
 
-            * If a list of python lists containing :class:`Bit` objects, a collection of
-              :class:`Bit` s to be added to the circuit.
+            * If a list of python lists containing :class:`.Bit` objects, a collection of
+              :class:`.Bit` s to be added to the circuit.
 
 
         name (str): the name of the quantum circuit. If not set, an
@@ -1218,7 +1218,7 @@ def append(
 
         Raises:
             CircuitError: if the operation passed is not an instance of
-                :class:`~.circuit..Instruction`.
+                :class:`~.circuit.Instruction`.
         """
         if isinstance(instruction, CircuitInstruction):
             operation = instruction.operation
@@ -1858,10 +1858,10 @@ def draw(
                 Default is True, except for when ``output`` is set to  ``"text"``.
             wire_order (list): Optional. A list of integers used to reorder the display
                 of the bits. The list must have an entry for every bit with the bits
-                in the range 0 to (num_qubits + num_clbits).
+                in the range 0 to (``num_qubits`` + ``num_clbits``).
 
         Returns:
-            :class:`TextDrawing` or :class:`matplotlib.figure` or :class:`PIL.Image` or
+            :class:`.TextDrawing` or :class:`matplotlib.figure` or :class:`PIL.Image` or
             :class:`str`:
 
             * `TextDrawing` (output='text')
@@ -2803,8 +2803,8 @@ def _rebind_definition(
                         self._rebind_definition(inner.operation, parameter, value)
 
     def barrier(self, *qargs: QubitSpecifier, label=None) -> InstructionSet:
-        """Apply :class:`~qiskit.circuit.Barrier`. If qargs is empty, applies to all qubits in the
-        circuit.
+        """Apply :class:`~qiskit.circuit.library.Barrier`. If ``qargs`` is empty, applies to all qubits
+        in the circuit.
 
         Args:
             qargs (QubitSpecifier): Specification for one or more qubit arguments.
@@ -2840,14 +2840,15 @@ def delay(
         qarg: Optional[QubitSpecifier] = None,
         unit: str = "dt",
     ) -> InstructionSet:
-        """Apply :class:`~qiskit.circuit.Delay`. If qarg is None, applies to all qubits.
+        """Apply :class:`~.~qiskit.circuit.library.Delay`. If qarg is ``None``, applies to all qubits.
         When applying to multiple qubits, delays with the same duration will be created.
 
         Args:
             duration (int or float or ParameterExpression): duration of the delay.
             qarg (Object): qubit argument to apply this delay.
-            unit (str): unit of the duration. Supported units: 's', 'ms', 'us', 'ns', 'ps', 'dt'.
-                Default is ``dt``, i.e. integer time unit depending on the target backend.
+            unit (str): unit of the duration. Supported units: ``'s'``, ``'ms'``, ``'us'``,
+            ``'ns'``, ``'ps'``, and ``'dt'``. Default is ``'dt'``, i.e. integer time unit
+            depending on the target backend.
 
         Returns:
             qiskit.circuit.InstructionSet: handle to the added instructions.
@@ -2953,7 +2954,7 @@ def id(self, qubit: QubitSpecifier) -> InstructionSet:  # pylint: disable=invali
         return self.i(qubit)
 
     def ms(self, theta: ParameterValueType, qubits: Sequence[QubitSpecifier]) -> InstructionSet:
-        """Apply :class:`~qiskit.circuit.library.generalized_gates.gms.MSGate`.
+        """Apply :class:`~qiskit.circuit.library.MSGate`.
 
         For the full matrix form of this gate, see the underlying gate documentation.
 
@@ -3074,9 +3075,9 @@ def rv(
         rotation in radians.
 
         Args:
-            vx: x-compenent of the rotation axis.
-            vy: y-compenent of the rotation axis.
-            vz: z-compenent of the rotation axis.
+            vx: x-component of the rotation axis.
+            vy: y-component of the rotation axis.
+            vz: z-component of the rotation axis.
             qubit: The qubit(s) to apply the gate to.
 
         Returns:
@@ -3507,8 +3508,8 @@ def cswap(
             target_qubit2: The qubit(s) targeted by the gate.
             label: The string label of the gate in the circuit.
             ctrl_state:
-                The control state in decimal, or as a bitstring (e.g. '1').  Defaults to controlling
-                on the '1' state.
+                The control state in decimal, or as a bitstring (e.g. ``'1'``).  Defaults to controlling
+                on the ``'1'`` state.
 
         Returns:
             A handle to the instructions created.
@@ -3849,10 +3850,10 @@ def mcx(
         The multi-cX gate can be implemented using different techniques, which use different numbers
         of ancilla qubits and have varying circuit depth. These modes are:
 
-        - 'noancilla': Requires 0 ancilla qubits.
-        - 'recursion': Requires 1 ancilla qubit if more than 4 controls are used, otherwise 0.
-        - 'v-chain': Requires 2 less ancillas than the number of control qubits.
-        - 'v-chain-dirty': Same as for the clean ancillas (but the circuit will be longer).
+        - ``'noancilla'``: Requires 0 ancilla qubits.
+        - ``'recursion'``: Requires 1 ancilla qubit if more than 4 controls are used, otherwise 0.
+        - ``'v-chain'``: Requires 2 less ancillas than the number of control qubits.
+        - ``'v-chain-dirty'``: Same as for the clean ancillas (but the circuit will be longer).
 
         For the full matrix form of this gate, see the underlying gate documentation.
 
@@ -3927,10 +3928,10 @@ def mct(
         The multi-cX gate can be implemented using different techniques, which use different numbers
         of ancilla qubits and have varying circuit depth. These modes are:
 
-        - 'noancilla': Requires 0 ancilla qubits.
-        - 'recursion': Requires 1 ancilla qubit if more than 4 controls are used, otherwise 0.
-        - 'v-chain': Requires 2 less ancillas than the number of control qubits.
-        - 'v-chain-dirty': Same as for the clean ancillas (but the circuit will be longer).
+        - ``'noancilla'``: Requires 0 ancilla qubits.
+        - ``'recursion'``: Requires 1 ancilla qubit if more than 4 controls are used, otherwise 0.
+        - ``'v-chain'``: Requires 2 less ancillas than the number of control qubits.
+        - ``'v-chain-dirty'``: Same as for the clean ancillas (but the circuit will be longer).
 
         For the full matrix form of this gate, see the underlying gate documentation.
 
@@ -4305,10 +4306,10 @@ def for_loop(
 
         There are two forms for calling this function.  If called with all its arguments (with the
         possible exception of ``label``), it will create a
-        :obj:`~qiskit.circuit.controlflow.ForLoopOp` with the given ``body``.  If ``body`` (and
+        :class:`~.ForLoopOp` with the given ``body``.  If ``body`` (and
         ``qubits`` and ``clbits``) are *not* passed, then this acts as a context manager, which,
         when entered, provides a loop variable (unless one is given, in which case it will be
-        reused) and will automatically build a :obj:`~qiskit.circuit.controlflow.ForLoopOp` when the
+        reused) and will automatically build a :class:`~.ForLoopOp` when the
         scope finishes.  In this form, you do not need to keep track of the qubits or clbits you are
         using, because the scope will handle it for you.
 
@@ -4490,7 +4491,7 @@ def if_else(
         clbits: Sequence[ClbitSpecifier],
         label: Optional[str] = None,
     ) -> InstructionSet:
-        """Apply :class:`~qiskit.circuit.controlflow.IfElseOp`.
+        """Apply :class:`~.IfElseOp`.
 
         .. note::
 
@@ -4535,7 +4536,7 @@ def if_else(
         return self.append(IfElseOp(condition, true_body, false_body, label), qubits, clbits)
 
     def break_loop(self) -> InstructionSet:
-        """Apply :class:`~qiskit.circuit.controlflow.BreakLoopOp`.
+        """Apply :class:`~.BreakLoopOp`.
 
         .. warning::
 
@@ -4565,7 +4566,7 @@ def break_loop(self) -> InstructionSet:
         return self.append(BreakLoopOp(self.num_qubits, self.num_clbits), self.qubits, self.clbits)
 
     def continue_loop(self) -> InstructionSet:
-        """Apply :class:`~qiskit.circuit.controlflow.ContinueLoopOp`.
+        """Apply :class:`~.ContinueLoopOp`.
 
         .. warning::