Prepare 2.1.0 release (#14565)

* Version update and first pass at the release notes

* Update releasenotes/notes/2.1/Added-random-circuit-from-graph-95c22eeabdea89d0.yaml

Co-authored-by: Rebecca Dimock <[email protected]>

* Apply comments from Becky's review

* Fix broken links and other formatting issues

* Apply fixes after proofreading

* Update feature notes

This commit goes through the new feature release notes and updates and
expands on them for clarity.

* Update other notes

* Update deprecation notes

* Update upgrade notes

* Update C API target note

* Add prelude

* Refine circuit library release note

Remove the mention of a migration guide

* Address review comments

* Remove duplicate sphinx directives

* Reword PauliLindbladMap note

* Fixup PauliLindbladMap wording

* Update releasenotes/notes/2.1/prepare-2.1.0-409d24ecbe277062.yaml

Co-authored-by: Matthew Treinish <[email protected]>

* Remove duplicate release notes from 2.0.x

* Resolve Pauli cross-reference in a release note

* Update fix notes

---------

Co-authored-by: Rebecca Dimock <[email protected]>
Co-authored-by: Matthew Treinish <[email protected]>
Co-authored-by: Jake Lishman <[email protected]>

Author: 4 people

Cargo.lock

@@ -3,7 +3,7 @@ members = ["crates/*"]
 resolver = "2"
 
 [workspace.package]
-version = "2.1.0-rc1"
+version = "2.1.0"
 edition = "2021"
 rust-version = "1.79"  # Keep in sync with README.md, rust-toolchain.toml, and tools/install_rust_msrv.sh
 license = "Apache-2.0"

Cargo.toml

@@ -1,3 +1,5 @@
+.. _C_API:
+
 ===========================
 Qiskit C API (``qiskit.h``)
 ===========================

docs/cdoc/index.rst

@@ -32,7 +32,7 @@
 # The short X.Y version
 version = "2.1"
 # The full version, including alpha/beta/rc tags
-release = "2.1.0rc1"
+release = "2.1.0"
 
 language = "en"
 

docs/conf.py

@@ -10,4 +10,4 @@ Qiskit |version| release notes
     `:earliest-version:` should be set to the rc1 release for the current minor release series. For example, the stable/1.1 branch should set it to 1.1.0rc1. If on `main`, set to the prior minor version's rc1, like `1.0.0rc1`.
 
 .. release-notes::
-   :earliest-version: 1.1.0rc1
+   :earliest-version: 2.1.0rc1

docs/release_notes.rst

@@ -1 +1 @@
-2.1.0rc1
+2.1.0

qiskit/VERSION.txt

@@ -377,7 +377,7 @@ class PiecewiseChebyshevGate(Gate):
             from qiskit import QuantumCircuit
             from qiskit.circuit.library.arithmetic import PiecewiseChebyshevGate
 
-            f_x, num_state_qubits, degree, breakpoints = lambda x: np.arcsin(1 / x), 2, 2, [2, 4]
+            f_x, num_state_qubits, degree, breakpoints = lambda x: np.sin(1 / x), 2, 2, [2, 4]
             pw_approximation = PiecewiseChebyshevGate(f_x, num_state_qubits, degree, breakpoints)
 
             qc = QuantumCircuit(pw_approximation.num_qubits)

qiskit/circuit/library/arithmetic/piecewise_chebyshev.py

@@ -91,6 +91,7 @@
    Split2QUnitaries
    RemoveIdentityEquivalent
    ContractIdleWiresInControlFlow
+   OptimizeCliffordT
 
 Scheduling
 =============

qiskit/transpiler/passes/__init__.py

@@ -361,6 +361,10 @@ def run(self, high_level_object, coupling_map=None, target=None, qubits=None, **
    :no-inherited-members:
    :no-special-members:
 
+.. automodule:: qiskit.transpiler.passes.synthesis.clifford_unitary_synth_plugin
+   :no-inherited-members:
+   :no-special-members:
+
 
 High Level Synthesis
 --------------------

qiskit/transpiler/passes/synthesis/plugin.py

@@ -1,36 +1,35 @@
 ---
 features_circuits:
   - |
-    Added a function :func:`~qiskit.circuit.random.utils.random_circuit_from_graph` that generates a random circuit that 
-    induces the same interaction graph as the interaction graph specified by `interaction_graph`.
+    Added a function :func:`~qiskit.circuit.random.random_circuit_from_graph` that generates a random circuit that
+    induces the same interaction graph as the one specified by `interaction_graph`.
 
-    The probability of randomly drawing an edge from the interaction graph as a two-qubit gate can be set by the 
-    user in the weight attribute of an edge in the input interaction graph. If the user does not set the probability, 
-    each edge is drawn uniformly, i.e. each two-qubit gate represented by an edge in the interaction graph has the 
-    same probability of getting added to the random circuit. If only a subset of edge probabilities are set, 
-    `ValueError` will be raised.
+    The probability of randomly drawing an edge from the interaction graph as a two-qubit gate can be set by the
+    user in an edge's weight attribute in the input interaction graph. If the user does not set the probability,
+    each edge is drawn uniformly.  That is, each two-qubit gate represented by an edge in the interaction graph has the
+    same probability of getting added to the random circuit. If only a subset of edge probabilities are set,
+    ``ValueError`` will be raised.
 
-    This is an example where 'cp_map' is a list of edges with some arbitrary weights.
+    In this example, ``cp_map`` is a list of edges with arbitrary weights.
 
     .. plot::
       :include-source:
-        
+
         from qiskit.circuit.random.utils import random_circuit_from_graph
         import rustworkx as rx
         pydi_graph = rx.PyDiGraph()
         n_q = 5
         cp_map = [(0, 1, 0.18), (1, 2, 0.15), (2, 3, 0.15), (3, 4, 0.22)]
-        pydi_graph.add_nodes_from(range(n_q))
-        pydi_graph.add_edges_from(cp_map)
+        pydi_graph.extend_from_weighted_edge_list(cp_map)
         # cp_map can be passed in directly as interaction_graph
         qc = random_circuit_from_graph(interaction_graph = pydi_graph,
-          min_2q_gate_per_edge = 1, 
-          max_operands = 2, 
-          measure = True, 
-          conditional = True, 
-          reset = True, 
-          seed = 0, 
-          insert_1q_oper = True, 
+          min_2q_gate_per_edge = 1,
+          max_operands = 2,
+          measure = True,
+          conditional = True,
+          reset = True,
+          seed = 0,
+          insert_1q_oper = True,
           prob_conditional = 0.21,
           prob_reset = 0.1)
         qc.draw(output='mpl')

releasenotes/notes/2.1/Added-random-circuit-from-graph-95c22eeabdea89d0.yaml

@@ -2,14 +2,13 @@
 features_transpiler:
   - |
     The function :func:`.generate_preset_pass_manager` now generates a special
-    pass manager when the basis set consists of Clifford+T gates only.
-    Formally, a Clifford+T basis set must contain either a :class:`.TGate` or
-    :class:`.TdgGate` (or both), and only Clifford gates in addition.
-    The full list of supported Clifford gates can be obtained using
-    :func:`.get_clifford_gate_names`.
+    pass manager when the basis set consists only of Clifford+T gates.
+    Formally, a Clifford+T basis set must contain only Clifford gates, along
+    with either :class:`.TGate`, :class:`.TdgGate`, or both. The full list of supported
+    Clifford gates can be obtained by using :func:`.get_clifford_gate_names`.
 
     For example::
-  
+
       from qiskit.circuit import QuantumCircuit
       from qiskit.transpiler.preset_passmanagers import generate_preset_pass_manager
       from qiskit.quantum_info import get_clifford_gate_names
@@ -22,25 +21,32 @@ features_transpiler:
       qct = pm.run(qc)
       print(qct.count_ops())
 
-    Previously, the generated pass manager was not able to handle the example above,
-    as it was not able to decompose single-qubit rotation gates of type
-    :class:`.UGate` into Clifford+T gates. Instead, the new pass manager uses the
-    the Solovay-Kitaev decomposition to approximate single-qubit rotation gates
+    Would result with:
+
+    .. code-block:: text
+
+      OrderedDict([('h', 10210), ('t', 4508), ('tdg', 4503), ('sdg', 943), ('s', 941)])
+
+
+    Previously, the generated pass manager could not handle the example above
+    because it couldn't decompose single-qubit :class:`.UGate` rotation gates into
+    Clifford+T gates. However, the new pass manager uses the
+    Solovay-Kitaev decomposition to approximate single-qubit rotation gates
     using ``H``, ``T`` and ``Tdg`` gates, and calls the :class:`~.BasisTranslator`
     transpiler pass to further translate the gates into the target basis set.
     The new pass manager also has other changes as to enable a more efficient
     translation into Clifford+T gates.
 
     It is important to note that the specified Clifford+T basis gate set should be
-    universal, or else transpilation might not succeed. While the gate set 
-    ``["h", "t", "tdg"]``or even ``["h", "t"]`` is sufficient for universality,
+    universal, or else transpilation might not succeed. While the gate set
+    ``["h", "t", "tdg"]`` or even ``["h", "t"]`` is sufficient for universality,
     it is recommended to add more Clifford gates to the set if possible, as
-    otherwise the translation might be less efficient. For example, not including
-    S-gate might trigger decomposing S-gates into pairs of T-gates (that is,
-    decomposing Clifford gates into non-Clifford gates, which might not be the
+    otherwise the translation might be less efficient. For example, if S-gate is not included,
+    S-gates might be decomposed into pairs of T-gates (that is,
+    Clifford gates might be decomposed into non-Clifford gates, which might not be the
     desired behavior).
 
-    Here is an additional slightly larger example::
+    Following is a slightly larger example::
 
       from qiskit.circuit import QuantumCircuit
       from qiskit.circuit.library import QFTGate
@@ -57,3 +63,9 @@ features_transpiler:
 
       qct = pm.run(qc)
       print(qct.count_ops())
+
+    Would result with:
+
+    .. code-block:: text
+
+      OrderedDict([('h', 96510), ('tdg', 42396), ('t', 42389), ('s', 8240), ('sdg', 8235), ('cx', 12)])

releasenotes/notes/2.1/add-clifford-t-transpiler-pipeline-e640b5ba64eab13a.yaml

@@ -1,24 +1,26 @@
 ---
 features_synthesis:
   - |
-    Added new synthesis algorithm for :class:`.HalfAdderGate` that requires no ancillary qubits
+    Added a new synthesis algorithm for :class:`.HalfAdderGate` that requires no ancillary qubits
     and has better CX count compared to :func:`.adder_qft_d00`:
 
     * :func:`.adder_ripple_r25`
 
 features_transpiler:
   - |
-    Added new high-level-synthesis plugin for synthesizing a :class:`.HalfAdderGate`:
-
-    * :class:`.HalfAdderSynthesisR25`, based on :func:`.adder_ripple_rv_25`.
+    Added a new high-level-synthesis plugin :class:`.HalfAdderSynthesisR25` for synthesizing a
+    :class:`.HalfAdderGate`. The new plugin is based on :func:`.adder_ripple_r25`.
 
     The :class:`.HalfAdderSynthesisDefault` has also been updated to follow the following sequence
-    of half adder synthesizers: ``"HalfAdder.ripple_r25"`` when the number of qubits is 
-    :math:`\leq 3`, ``"HalfAdder.ripple_c04"`` when 1 ancillary qubit is available, 
+    of half adder synthesizers: ``"HalfAdder.ripple_r25"`` when there are
+    :math:`\leq 3` qubits, ``"HalfAdder.ripple_c04"`` when one ancillary qubit is available, and
     ``"HalfAdder.ripple_r25"`` in all remaining cases.
 
 upgrade_circuits:
   - |
-    The circuit definition of :class:`.HalfAdderGate` has been upgraded to use
-    :func:`.adder_ripple_r25`. To obtain the old behaviour, use the definition of
-    :func:`.adder_qft_d00` instead.
+    The :attr:`~.HalfAdderGate.definition` attribute of the :class:`.HalfAdderGate`
+    has been changed to internally use :func:`.adder_ripple_r25` to generate the definition
+    of the gate for a more efficient circuit with no ancillary qubits. If the old definition
+    is desired for some reason you can directly use the :func:`.adder_qft_d00` function instead which
+    will generate a circuit equivalent to what :attr:`~.HalfAdderGate.definition` would return
+    in previous releases.

releasenotes/notes/2.1/add-new-half-adder-6532be58252b2a86.yaml

@@ -8,6 +8,8 @@ features_transpiler:
     * :class:`.MCXSynthesis2CleanKG24`, based on :func:`.synth_mcx_2_clean_kg24`.
     * :class:`.MCXSynthesis2DirtyKG24`, based on :func:`.synth_mcx_2_dirty_kg24`.
 
-    The :class:`.MCXSynthesisDefault` has also been updated to follow the following sequence of
-    MCX synthesizers: "mcx.2_clean_kg24", "mcx.1_clean_kg24", "mcx.n_clean_m15", "mcx.n_dirty_i15",
-    "mcx.2_dirty_kg24", "mcx.1_dirty_kg24" "mcx.1_clean_b95", "mcx.noaux_v24".
+    The :class:`.MCXSynthesisDefault` class has also been updated to run the following
+    sequence of MCX synthesize methods until the first one succeeds:
+    : ``"mcx.2_clean_kg24"``, ``"mcx.1_clean_kg24"``, ``"mcx.n_clean_m15"``, ``"mcx.n_dirty_i15"`,
+    ``"mcx.2_dirty_kg24"``, ``"mcx.1_dirty_kg24"``, ``"mcx.1_clean_b95"``, ``"mcx.noaux_v24"``. The methods
+    are ordered in a way that the better-quality ones are applied first.

releasenotes/notes/2.1/add-new-mcx-plugins-2177db9195e2b680.yaml

@@ -1,4 +1,4 @@
 features_circuits:
   - |
-    Added :meth:`.QuantumCircuit.has_control_flow` to check if a circuit
-    contains any control flow operations.
+    Added a new :class:`.QuantumCircuit` method: :meth:`.QuantumCircuit.has_control_flow_op` to
+    check if a :class:`.QuantumCircuit` object contains any control flow operations.

releasenotes/notes/2.1/add_has_control_flow-8b4f4e8170a52235.yaml

@@ -1,15 +1,15 @@
 ---
 features_circuits:
   - |
-    A new module :mod:`qiskit.circuit.annotation` and principle object :class:`.Annotation` have
-    been added.
+    A new module :mod:`qiskit.circuit.annotation` and principle object :class:`.Annotation`
+    have been added.
 
-    Annotations are a way of tagging instructions (currently only :class:`.BoxOp`, in the initial
-    implementation) with local, user-custom data.  This data is intended to be consumed by custom
+    Annotations are a way of tagging instructions (currently only :class:`.BoxOp`)
+    with local, user-custom data.  This data is intended to be consumed by custom
     transpiler passes.  Annotations provide a way to attach data to specific instructions, rather
     than using the global-context object :class:`.PropertySet` during compilation.
 
-    All :class:`.Annotation` objects have a :attr:`~.Annotation.namespace`. This string key is used
+    All :class:`.Annotation` objects have a ``namespace`` field. This string key is used
     for lookups, so consumers can tell if they handle a particular annotation or not.  There are
     currently no methods for querying any abstract semantics of an :class:`.Annotation` subclass,
     but these are expected to expand in the future.
@@ -37,7 +37,7 @@ features_circuits:
 
 features_qpy:
   - |
-    QPY version 15 is released, including support for the new :class:`.Annotation` objects, with
+    Added a new QPY format version 15 which includes support for the new :class:`.Annotation` objects, with
     support from external serializers and deserializers.  The format allows such serializers to be
     stateful, and safe places in the binary format are allocated for the custom state objects and
     custom annotation representations.
@@ -47,6 +47,11 @@ features_qpy:
     handle :class:`.Annotation` subclasses.  These must be supplied by the user, similar to
     ``metadata_serializer``, as in general, Qiskit cannot know about all possible externally-defined
     :class:`.Annotation` objects.
+upgrade_qpy:
+  - |
+    The default QPY version emitted by :func:`.qpy.dump` has been changed to the latest QPY version 15.
+    If you need to generate an older format version for some reason you can use the ``version`` keyword
+    argument on :func:`.qpy.dump` to specify an older version to generate.
 
 features_qasm:
   - |