This document describes breaking changes and how to upgrade. For a complete list of changes including minor and patch releases, please refer to the changelog.
This release introduces a Qiskit BackendV2-compatible interface to QDMI devices.
The mqt.core.plugins.qiskit module has been extended with QDMIProvider, QDMIBackend, and QDMIJob classes that allow running Qiskit circuits on QDMI-compliant devices.
Users can now execute Qiskit circuits directly on QDMI devices:
from mqt.core.plugins.qiskit import QDMIProvider
provider = QDMIProvider()
backend = provider.get_backend("MQT Core DDSIM QDMI Device")
job = backend.run(circuit, shots=1024)
result = job.result()The backend automatically converts circuits to QASM, introspects device capabilities, validates circuits, and formats results.
The existing FoMaC interface (mqt.core.fomac) remains fully supported for direct, low-level access to QDMI devices.
Install with Qiskit support: pip install "mqt-core[qiskit]"
See the Qiskit Backend documentation for details.
Since we enabled ty for type checking, it revealed that some of the dunder methods of QuantumComputation and CompoundOperation had incorrect argument names, which would prevent these classes from properly implementing the MutableSequence protocol.
This release fixes these issues by renaming the arguments of the following methods:
QuantumComputation.__getitem__QuantumComputation.__setitem__QuantumComputation.__delitem__QuantumComputation.insertQuantumComputation.appendCompoundOperation.__getitem__CompoundOperation.__setitem__CompoundOperation.__delitem__CompoundOperation.insertCompoundOperation.append
All index arguments are now named index instead of idx (or i or slice) and all values are now named value instead of val (or op or ops).
This release moves the DD Package evaluation functionality from within the mqt.core package to a dedicated script in the eval directory.
In the process, the mqt-core-dd-compare entry point as well as the evaluation extra have been removed.
The eval/dd_evaluation.py script acts as a drop-in replacement for the previous CLI entry point.
Since the eval directory is not part of the Python package, this functionality is only available via source installations or by cloning the repository.
Free-threading Python was introduced as an experimental feature in Python 3.13. It became stable in Python 3.14. To conserve space on PyPI and to reduce the CD build times, we have removed all wheels for Python 3.13t from our CI. We continue to provide wheels for the regular Python versions 3.10 to 3.14, as well as 3.14t.
The shared library ABI version (SOVERSION) is increased from 3.2 to 3.3.
Thus, consuming libraries need to update their wheel repair configuration for cibuildwheel to ensure the mqt-core libraries are properly skipped in the wheel repair step.
This release introduces an IfElseOperation to the C++ library and the Python package to support Qiskit's IfElseOp.
The new operation replaces the ClassicControlledOperation.
An IfElseOperation can be added to a QuantumComputation using if_else().
qc.if_else(
then_operation=StandardOperation(target=0, op_type=OpType.x),
else_operation=StandardOperation(target=0, op_type=OpType.y),
control_bit=0,
)If no else operation is needed, the if_() method can be used.
qc.if_(op_type=OpType.x, target=0, control_bit=0)Starting with this release, MQT Core no longer supports Python 3.9. This is in line with the scheduled end of life of the version. As a result, MQT Core is no longer tested under Python 3.9 and no longer ships Python 3.9 wheels.
The shared library ABI version (SOVERSION) is increased from 3.1 to 3.2.
Thus, consuming libraries need to update their wheel repair configuration for cibuildwheel to ensure the mqt-core libraries are properly skipped in the wheel repair step.
With this release, the minimum required C++ version has been raised from C++17 to C++20. The default compilers of our test systems support all relevant features of the standard. Some frameworks we plan to integrate with even require C++20 by now.
The dd.BasisStates, ir.operations.ComparisonKind, ir.operations.Control.Type, and ir.operations.OpType enums are now exposed via pybind11's new py::native_enum, which makes them compatible with Python's enum.Enum class (PEP 435).
As a result, the enums can no longer be initialized using a string.
Instead of OpType("x"), use OpType.x.
The shared library ABI version (SOVERSION) is increased from 3.0 to 3.1.
Thus, consuming libraries need to update their wheel repair configuration for cibuildwheel to ensure the mqt-core libraries are properly skipped in the wheel repair step.
Even though this is not a breaking change, it is worth mentioning to developers of MQT Core that all Python code (except tests) has been moved to the top-level python directory.
Furthermore, the C++ code for the Python bindings has been moved to the top-level bindings directory.
The makeZeroState, makeBasisState, makeGHZState, makeWState, and makeStateFromVector methods have been refactored to functions taking the DD package as an argument. These functions reside in the StateGeneration header. Any existing code that uses these methods must replace the respective calls with their function counterpart.
This major release introduces several breaking changes, including the removal of deprecated features and the introduction of new APIs. In preparation for this release, most direct dependents of MQT Core have been updated to use the new APIs. The following sections describe the most important changes and how to adapt your code accordingly. We intend to provide a more comprehensive migration guide for future releases.
The OpenQASM parser has been encapsulated in its own library, which is now a dedicated target in the CMake build system.
Any use of qc::QuantumComputation::import... needs to be replaced with the respective qasm3::Importer::load... function.
Several parsers have been removed, including the .real, .qc, .tfc, and GRCS parsers.
The .real parser lives on as part of the MQT SyReC project. All others have been removed without replacement.
The Teleportation gate has been removed from the IR. This was a placeholder gate and was only used in a single method (in MQT QMAP), which is bound to be removed as part of MQT QMAP v3.0.0.
MQT QCEC, MQT QMAP, and MQT DDSIM have been updated to use the new API, which will be released in MQT QCEC v3.0.0, MQT QMAP v3.0.0 and MQT DDSIM v2.0.0.
The DD package has undergone some initial refactoring to streamline the implementation and prepare it for future extensions.
The Config template has been removed in favor of a constructor that takes the configuration as a parameter.
Any existing code using dd::Package<...> needs to be updated to use dd::Package or dd::Package(numQubits, ...) instead.
The MemoryManager and adjacent classes have been refactored to remove the template parameters.
This should not have user-visible effects, but it is a breaking change nonetheless.
Depending libraries may now also use the mqt-core Python package to interact with the DD package.
MQT QCEC and MQT DDSIM have been updated to use the new API, which will be released in MQT QCEC v3.0.0 and MQT DDSIM v2.0.0.
The NAComputation class hierarchy has been refactored to use an MLIR-inspired design. This will act as a foundation for future extensions and improvements.
MQT QMAP has been updated to use the new API, which will be released in MQT QMAP v3.0.0.
MQT Core has moved to the munich-quantum-toolkit GitHub organization under https://github.com/munich-quantum-toolkit/core. While most links should be automatically redirected, please update any links in your code to point to the new location. All links in the documentation have been updated accordingly.
MQT Core now ships all its C++ libraries as shared libraries with the mqt-core Python package.
Depending packages can now solely rely on the Python package for obtaining the C++ libraries.
This is demonstrated in MQT QCEC v3.0.0, MQT QMAP v3.0.0 and MQT DDSIM v2.0.0, which will be released in the near future.
MQT Core now requires CMake 3.24 or higher.
Most modern operating systems should have this version available in their package manager.
Alternatively, CMake can be conveniently installed from PyPI using the cmake package.
It also requires the uv library version 0.5.20 or higher.