Prepare 0.12.0 release

releasenotes/notes/0.12/add-NoiseModel-from_backendproperties-1a3d6d976133a661.yaml

@@ -0,0 +1,10 @@
+---
+features:
+  - |
+    Added a new class method :meth:`~.NoiseModel.from_backend_properties` to
+    the :class:`NoiseModel`. This enables constructing a new :class:`~.NoiseModel`
+    from a :class:`~qiskit.providers.BackendProperties` object. Similar functionality used
+    to be present in the :meth:`.NoiseModel.from_backend` constructor,
+    however it was removed since a :class:`~qiskit.providers.BackendProperties` object alone
+    doesn't contain sufficient information to create a :class:`~.NoiseModel`
+    object.

releasenotes/notes/0.12/add-aer-density-matrix-e2439120b24c91c9.yaml

@@ -0,0 +1,7 @@
+---
+features:
+  - |
+    Added a new class, :class:`~.AerDensityMatrix`, to the :mod:`qiskit_aer.quantum_info`
+    module. This class is used to provide the same interface to the
+    upstream :class:`~qiskit.quantum_info.DensityMatrix` class in Qiskit but backed by
+    Qiskit Aer's simulation.

releasenotes/notes/0.12/add-grouping-fcc4fad69ccdac26.yaml

@@ -0,0 +1,18 @@
+---
+features:
+  - |
+    Added a new keyword argument, ``abelian_grouping``, to
+    the :class:`~.Estimator`. This argument is used to control whether the
+    :class:`~.Estimator` will group the input observables into qubit-wise
+    commutable observables which reduces the number of circuit executions
+    required to compute the expectation value and improves the runtime
+    performance of the :class:`~.Estimator`. By default this is set to
+    ``True``.
+upgrade:
+  - |
+    The default behavior of the :class:`~.Estimator` primitive will now
+    group the input observable into qubit-wise commutable observables.
+    The grouping reduces the number of circuits to be executed and improves
+    the performance. If you desire the previous behavior you can initialize
+    your :class:`~.Estimator` instance with the keyword argument
+    ``abelian_grouping=False``.

releasenotes/notes/0.12/fix-ndarray-contiguity-e903d0fda4744100.yaml

@@ -0,0 +1,9 @@
+---
+fixes:
+  - |
+    Fixed an issue when creating a new :class:`~.AerStatevector` instance
+    from a ``numpy.ndarray`` that had non-contiguous memory. Previously,
+    this would result in unexpected behavior (and a potential error) as
+    the :class:`~.AerStatevector` assumed the input array was contiguous. This
+    has been fixed so that memory layout is checked and the ``numpy.ndarray``
+    will be copied internally as a contiguous array before using it.

releasenotes/notes/0.12/fix-split-cregs-5b5494a92c4903e7.yaml

@@ -0,0 +1,7 @@
+---
+fixes:
+  - |
+    Fixed an issue with the :class:`.Sampler` class where it would previously
+    fail if the input :class:`~.QuantumCircuit` contained multiple
+    multiple classical registers.
+    Fixed `#1679 <https://github.com/Qiskit/qiskit-aer/issues/1679>`__

releasenotes/notes/0.12/mps_fix_apply_measure-84c29a728ae0e717.yaml

@@ -0,0 +1,14 @@
+---
+
+fixes:
+  - |
+    Fixed an issue in the matrix product state simulation method (i.e.
+    setting the keyword argument ``method="matrix_product_state"`` when
+    initializing an :class:`~.AerSimulator` object) where the simulator
+    would incorrectly sort the qubits prior to performing measurment
+    potentially resulting in an infinite loop. This has been fixed so
+    the measurement of the qubits occurs in the order of the current MPS
+    structure and then sorting afterwards as a post-processing step. This also
+    will likely improve the performance of the simulation method and enable
+    more accurate representation of entangled states.
+    Fixed `#1694 <https://github.com/Qiskit/qiskit-aer/issues/1694>`__

releasenotes/notes/0.12/optimized_stabilizer-f696742e7f881d0d.yaml

@@ -0,0 +1,9 @@
+---
+Features:
+  - |
+    The performance of the ``stabilizer`` simulation method (i.e. when setting 
+    the keyword argument ``method="stabilizer"`` when initializing an
+    :class:`~.AerSimulator` instance) has been improved. This
+    was accomplished by changing the internal data order to align data access
+    for improved CPU cache locality and improving the efficiency of integer
+    bit operations.

releasenotes/notes/0.12/own_assembler-0c76e67a054bd12c.yaml

@@ -0,0 +1,48 @@
+---
+features:
+  - |
+    The overhead for running simulations with :meth:`~.AerSimulator.run`
+    (for all simulator backend classess) has been greatly reduced. This was
+    accomplished by no longer internally serializing
+    :class:`~qiskit.circuit.QuantumCircuit` objects into
+    :class:`~qiskit.qobj.QasmQobj` and instead the
+    :class:`~qiskit.circuit.QuantumCircuit` object directly to
+    an internal C++  circuit structure used for simulation. This improvement
+    is most noticeable for simulations of circuts with a small number of qubits
+    or parameterized circuits using the ``parameter_binds`` keyword argument
+    of :meth:`~.AerSimulator.run`.
+    Note that pulse simualation (via the now deprecated :class:`~.PulseSimulator`)
+    and DASK-based simulation still use the internal serialization and will
+    not see this performance improvement.
+  - |
+    Added a new method to the :class:`~.AerJob`, :meth:`~.AerJob.circuits`, which
+    returns  a list of :class:`~qiskit.circuit.QuantumCircuit` objects. This method returns
+    ``None`` if Qobj is used for simulation.
+deprecations:
+  - |
+    The :meth:`~.AerJob.qobj` method of the :class:`AerJob` class is
+    now deprecated and will be removed in a future release. The use of
+    the qobj format as input to :meth:`~.AerSimulator.run` has been
+    deprecated since qiskit-aer 0.9.0 and in most cases this method
+    would return ``None`` now anyway. If you'd like to get the input
+    to the ``run()`` method now you can use the :meth:`~.AerJob.circuits`
+    method instead, which will return the :class:`~.QuantumCircuit`
+    objects that were simulated in the job.
+upgrade:
+  - |
+    The behavior of :meth:`~.AerSimulator.run` method has changed when invalid
+    or otherwise unsimulatable :class:`~.QuantumCircuit` objects are passed as
+    an input. Previously, in these cases the :meth:`~.AerSimulator.run` method
+    would return an :class:`~.AerJob` whose :meth:`~.AerJob.result` method would
+    return a :class:`~.Result` with the ``ERROR`` or ``PARTIAL COMPLETED``
+    (depending on whether all the circuit inputs or only some were invalid or not).
+    Starting in this release instead of returning a result object with these statuses
+    an exception will be raised instead. This change was necessary because
+    of the performance improvements by no longer internally serializing the
+    :class:`~.QuantumCircuit` objects to a Qobj before passing it to C++, instead
+    the direct conversion from :class:`~.QuantumCircuit` now errors directly when
+    trying to simulate a circuit Qiskit Aer is unable to execute. If you desire the
+    previous behavior you can build Qiskit Aer in standalone mode and manually
+    serialize your :class:`~.QuantumCircuit` objects to a JSON representation of
+    the :class:`~.QasmQobj` which you then pass to the standalone Aer binary
+    which will retain the previous behavior.

releasenotes/notes/0.12/prepare-0.12-0da477fc0492ca5d.yaml

@@ -0,0 +1,13 @@
+---
+prelude: >
+  The Qiskit Aer 0.12.0 release highlights are:
+
+    * Added a new GPU tensor network simulator based on
+      `cuTensorNet <https://docs.nvidia.com/cuda/cuquantum/cutensornet/index.html>`__
+    * Added a new :class:`~.AerDensityMatrix` class to the :mod:`qiskit_aer.quantum_info` module
+    * Greatly improving the runtime performance of the :class:`~.AerSimulator` and the legacy
+      :class:`~.QasmSimulator`, :class:`~.StatevectorSimulator`, and :class:`~.UnitarySimulator`
+      classes by directly converting the input :class:`~.QuantumCircuit` objects to an internal
+      C++ representation instead of first serializing the circuit to a :class:`~.QasmQobj`. This
+      improvement will be most noticeable for circuits with a small number of qubits or parameterized
+      circuits using the ``parameter_binds`` keyword argument.

releasenotes/notes/0.12/remove-qobj-684e68e99b212973.yaml

@@ -0,0 +1,8 @@
+---
+upgrade:
+  - |
+    The previously deprecated ``qobj`` argument name of the
+    :class:`~.AerSimulator` and :class:`~.PulseSimulator` classes'
+    :meth:`~.AerSimulator.run` method has now been removed. This argument
+    name was deprecated as part of the Qiskit Aer 0.8.0 release and has
+    been by the ``circuits`` and ``schedules`` argument name respectively.

releasenotes/notes/remove-setup_requires-751a406e2782885e.yaml → releasenotes/notes/0.12/remove-setup_requires-751a406e2782885e.yaml

@@ -3,7 +3,7 @@ upgrade:
   - |
     Aer's ``setup.py`` has been updated to no longer attempt to make calls to ``pip`` to
     install build requirements, both manually and via the ``setup_requires`` option in
-    ``setuptools.setup``.  The preferred way to build Aer is to use a PEP 517-compatible
+    ``setuptools.setup``.  The preferred way to build Aer is to use a `PEP 517 <https://peps.python.org/pep-0517/>`__-compatible
     builder such as:
 
     .. code-block:: text

releasenotes/notes/0.12/tensor_network_gpu-e8eb3e40be3c35f7.yaml

@@ -0,0 +1,24 @@
+---
+features:
+  - |
+    Added a new simulation method based on NVIDIA's `cuTensorNet <https://docs.nvidia.com/cuda/cuquantum/cutensornet/index.html>`__
+    APIs of cuQuantum SDK. This provides a GPU accelerated general tensor
+    network simulator that can simulate any quantum circuit, by internally
+    translating the circuit into a tensor network to perform the simulation.
+    To use this simulation method, set ``method="tensor_network"`` and
+    ``device="GPU"`` when initializing an :class:`~.AerSimulator` object.
+    For example::
+
+        from qiskit_aer import AerSimulator
+
+        tensor_net_sim = AerSimulator(method="tensor_network", device="GPU")
+
+    This method supports both statevector and density matrix simulations.
+    Noise simulation can also be done with a density matrix single shot
+    simulation if there are not any :class:`~.SaveStatevector` operations
+    in the circuit.
+
+    This new simulation method also supports parallelization with multiple GPUs and
+    MPI processes by using tensor network slicing technique. However, this type of
+    simulation will likely take a very long time if the input circuits are
+    complicated.

releasenotes/notes/0.12/use_conan_1.x-f12570e2cfc8bb26.yaml

@@ -0,0 +1,9 @@
+---
+issues:
+  - |
+    This release of Qiskit Aer is not compatible with the Conan 2.X release
+    series. If you are building Qiskit Aer from source manually ensure that
+    you are using a Conan 1.x release. Compatibility with newer versions
+    of Conan will be fixed in a future release. You can refer to
+    issue `#1730 <https://github.com/Qiskit/qiskit-aer/issues/1730>`__ for
+    more details.

releasenotes/notes/0.12/use_specified_bla_vendor-ca0322e993378048.yaml

@@ -0,0 +1,8 @@
+---
+features:
+  - |
+    The ``BLA_VENDOR`` environment variable can now be specified to use a
+    different BLAS library when building Qiskit Aer from source. By default
+    if this is not specified OpenBLAS will be used by default. If
+    the BLAS library specified in `BLA_VENDOR`` can not be found then the
+    Cmake build process will stop.