Prepare 0.9 release (#1344)

Co-authored-by: Matthew Treinish <mtreinish@kortar.org>

docs/apidocs/parallel.rst

@@ -1,3 +1,5 @@
+.. _dask:
+
 Running with Threadpool and DASK
 ================================
 

qiskit/providers/aer/library/__init__.py

@@ -61,13 +61,6 @@
 Saving Simulator Data
 =====================
 
-.. note ::
-    Each save instruction has a default label for accessing from the
-    circuit result data, however duplicate labels in results will result
-    in an exception being raised. If you use more than 1 instance of a
-    specific save instruction you must set a custom label for the
-    additional instructions.
-
 Simulator State Save Instruction Classes
 ----------------------------------------
 
@@ -95,6 +88,14 @@
     methods, however all other save state instructions must be applied
     to all qubits in a run circuit.
 
+.. note::
+    The :class:`~qiskit.providers.aer.StatevectorSimulator` (and
+    :class:`~qiskit.providers.aer.UnitarySimulator`) backend automatically
+    append every run circuit with the a :func:`SaveStatevector``
+    (:func:`SaveUnitary``) instruction using the default label. Hence adding
+    any additional save instructions of that type will require specifying a
+    custom label for those instructions.
+
 Simulator Derived Data Save Instruction Classes
 -----------------------------------------------
 
@@ -137,6 +138,13 @@
 The save instructions can also be added to circuits by using the
 following ``QuantumCircuit`` methods which are patched when importing Aer.
 
+.. note ::
+    Each save method has a default label for accessing from the
+    circuit result data, however duplicate labels in results will result
+    in an exception being raised. If you use more than 1 instance of a
+    specific save instruction you must set a custom label for the
+    additional instructions.
+
 .. autosummary::
     :toctree: ../stubs/
 

releasenotes/notes/0.9/0.9-release-0ecba93a5191e7ec.yaml

@@ -0,0 +1,77 @@
+---
+prelude: |
+    The 0.9 release includes new backend options for parallel exeuction
+    of large numbers of circuits on a HPC cluster using a Dask distributed,
+    along with other general performance improvements and bug fixes.
+features:
+  - |
+    Add qiskit library :class:`~qiskit.circuit.library.SXdgGate`
+    and :class:`~qiskit.circuit.library.CUGate` to the supported basis gates for
+    the Aer simulator backends. Note that the :class:`~qiskit.circuit.library.CUGate`
+    gate is only natively
+    supported for the ``statevector`` and ``unitary`` methods. For other simulation
+    methods it must be transpiled to the supported basis gates for that method.
+  - |
+    Adds support for N-qubit Pauli gate (
+    :class:`qiskit.circuit.library.generalized_gates.PauliGate`) to all
+    simulation methods of the
+    :class:`~qiskit.providers.aer.AerSimulator` and
+    :class:`~qiskit.providers.aer.QasmSimulator`.
+deprecations:
+  - |
+    Passing an assembled qobj directly to the
+    :meth:`~qiskit.providers.aer.AerSimulator.run` method of the Aer simulator
+    backends has been deprecated in favor of passing transpiled circuits
+    directly as ``backend.run(circuits, **run_options)``.
+  - |
+    All snapshot instructions in :mod:`qiskit.providers.aer.extensions` have
+    been deprecated. For replacement use the save instructions from the
+    :mod:`qiskit.providers.aer.library` module.
+  - |
+    Adding non-local quantum errors to a
+    :class:`~qiskit.providers.aer.noise.NoiseModel` has been deprecated due to
+    inconsistencies in how this noise is applied to the optimized circuit.
+    Non-local noise should be manually added to a scheduled circuit in Qiskit
+    using a custom transpiler pass before being run on the simulator.
+  - |
+    Use of the ``method`` option of the
+    :class:`~qiskit.providers.aer.StatevectorSimulator`, and 
+    :class:`~qiskit.providers.aer.UnitarySimulator` to run a GPU simulation
+    has been deprecated. To run a GPU simulation on a compatible system
+    use the option ``device='GPU'`` instead.
+upgrade:
+  - |
+    The default basis for the :class:`~qiskit.providers.aer.noise.NoiseModel`
+    class has been changed from ``["id", "u3", "cx"]`` to
+    ``["id", "rz", "sx", "cx"]`` due to the deprecation of the ``u3`` circuit
+    method in qiskit-terra and change of qiskit-ibmq-provider backend basis
+    gates. To use the old basis gates you can initialize a noise model with
+    custom basis gates as ``NoiseModel(basis_gates=["id", "u3", "cx"])``.
+  - |
+    Removed the ``backend_options`` kwarg from the ``run`` methnod of Aer backends
+    that was deprecated in qiskit-aer 0.7. All run options must now be passed as
+    separate kwargs.
+  - |
+    Removed passing ``system_model`` as a positional arg for the ``run`` method of the
+    :class:`~qiskit.providers.aer.PulseSimulator`.
+fixes:
+  - |
+    Fixes bug where the if the required memory is smaller than the system memory the
+    multi-chunk simulation method was enabled and simulation was still started.
+    This case will now throw an insufficient memory exception.
+  - |
+    Fixes issue where setting the ``shots`` option for a backend with
+    ``set_options(shots=k)`` was always running the default number of shots (1024)
+    rather than the specified value.
+  - |
+    Fixes a bug in how the :class:`~qiskit.providers.aer.AerSimulator` handled the
+    option value for ``max_parallel_experiments=1``. Previously this was treated
+    the same as ``max_parallel_experiments=0``.
+  - |
+    Fixes bug in the ``extended_stabilizer`` simulation method where it
+    incorrectly treated qelay gate and multi-qubit Pauli instructions as
+    unsupported.
+  - |
+    Fixes typo in the :class:`~qiskit.providers.aer.AerSimulator` and
+    :class:`~qiskit.providers.aer.QasmSimulator` options for the
+    ``extended_stabilizer_norm_estimation_repetitions`` option.

releasenotes/notes/0.9/custom-executor-3d0048b4dd4fa722.yaml

@@ -0,0 +1,30 @@
+---
+features:
+  - |
+    Adds the ability to set a custom executor and configure job splitting for
+    executing multiple circuits in parallel on a HPC clustor. A custom
+    executor can be set using the ``executor`` option, and job splitting is
+    configured by using the ``max_job_size`` option.
+    
+    For example configuring a backend and executing using
+
+    .. code-block:: python
+
+       backend = AerSimulator(max_job_size=1, executor=custom_executor)
+       job = backend.run(circuits)
+    
+    will split the exection into multiple jobs each containing a single
+    circuit. If job splitting is enabled the ``run`` method will return a
+    :class:`~qiskit.providers.aer.jobs.AerJobSet` object containing all the
+    individual :class:`~qiskit.providers.aer.jobs.AerJob` classes. After all
+    individual jobs finish running the job results are automatically combined
+    into a single Result object that is returned by ``job.result()``.
+
+    Supported executors include those in the Python ``concurrent.futures``
+    `module <https://docs.python.org/3/library/concurrent.futures.html>`__
+    (eg. ``ThreadPoolExecutor``, ``ProcessPoolExecutor``), and
+    `Dask <http://dask.org>`__ distributed  Client executors if the optional
+    dask library is installed. Using a Dask executor allows configuring parallel
+    execution of multiple circuits on HPC clusters. See the 
+    Dask executor :ref:`API Documentation <dask>` for additional details
+    on using Dask executors for HPC simulation.

releasenotes/notes/0.9/mps-e81837c4acd0e0f0.yaml

@@ -0,0 +1,30 @@
+---
+features:
+  - |
+    Adds ability to record logging data for the ``matrix_product_state``
+    simulation method to the experiment result metadata by setting the
+    backend option  ``mps_log_data=True``. The saved data includes the
+    bond dimensions and the discarded value (the sum of the squares of
+    the Schmidt coeffients that were discarded by approximation) after
+    every relevant circuit instruction.
+fixes:
+  - |
+    Fixes bug with applying the ``unitary`` gate in using the ``matrix_product_state``
+    simulation method which did not correctly support permutations in the ordering of
+    the qubits on which the gate is applied.
+  - |
+    Fixes an issue where gate fusion could still be enabled for the
+    ``matrix_product_state`` simulation method even though it is not supported. 
+    Now fusion is always disabled for this method.
+  - |
+    Fixed bug in the ``matrix_product_state`` simulation method in computing the
+    normalization following truncation of the  Schmidt coefficients after
+    performing the SVD.
+other:
+  - |
+    Improves the performance of the measurement sampling algorithm for the
+    ``matrix_product_state`` simulation method.
+    The new default behaviour is to always sample using the
+    improved ``mps_apply_measure`` method. The ``mps_probabilities`` sampling
+    method be still used by setting the custom option value
+    ``mps_sample_measure_algorithm="mps_probabilities"``.