QIR Support in the MQT

The Quantum Intermediate Representation (QIR) is a standardized intermediate representation for quantum programs based on the LLVM intermediate representation (LLVM IR).

The QIR Runtime in MQT Core

MQT Core provides a runtime for QIR that is based on its decision diagram-based quantum simulator. This allows for the execution of QIR programs using MQT Core’s high-performance simulation capabilities.

The runtime can be utilized in two ways:

  1. As a standalone library that can be linked to any QIR program, resulting in a binary executable.

  2. By using the mqt-core-qir-runner command-line tool, which interprets QIR programs directly.

See [38] for more details.

Building the Runner

To build this tool, the CMake option BUILD_MQT_CORE_QIR_RUNNER has to be enabled. It is enabled by default, but depends on BUILD_MQT_CORE_MLIR being set. From the root of the repository, you can build the runner as follows:

cmake -S . -B build -DBUILD_MQT_CORE_QIR_RUNNER=ON -DBUILD_MQT_CORE_MLIR=ON
cmake --build build --target mqt-core-qir-runner

After building, the tool can be found in the build directory under bin/mqt-core-qir-runner.

Executing a QIR Program

The mqt-core-qir-runner can be used to execute a QIR file (typically with a .ll extension).

./build/bin/mqt-core-qir-runner bell.ll

This will simulate the circuit and print the measurement results to the console. The runner supports the QIR Base Profile.

QIR Support in the DDSIM QDMI Device

The QDMI Device accepts jobs in the following program formats: QASM2, QASM3, QIR Base/Adaptive Profile Module (LLVM bitcode), and QIR Base/Adaptive Profile String (LLVM assembly). These QIR formats are only supported when the BUILD_MQT_CORE_QDMI_DDSIM_WITH_QIR CMake option is enabled. It is enabled by default, but depends on BUILD_MQT_CORE_MLIR being set.