Use the bundled example driver and mock device for an implementation smoke test. This path checks sessions, discovery, program submission, and result retrieval locally, without cloud credentials, an HPC allocation, or access to quantum hardware. The mock returns synthetic results; it does not simulate the supplied quantum circuit.

For circuit execution, start with MQT Core's simulator tutorial.

The CMake installation guide explains the selected revision and how to install the interface headers. A driver and its devices must implement the interface version you use; see the upgrade guide.

Build the Local Examples

You need Git, CMake 3.24 or newer, and C11 and C++20 compilers. Configuration fetches GoogleTest and initially needs network access. From a new checkout:

git clone \
  https://github.com/Munich-Quantum-Software-Stack/QDMI.git
cd QDMI
git checkout v1.4.0
 
cmake -S . -B build -DCMAKE_BUILD_TYPE=Release \
  -DBUILD_QDMI_TESTS=ON -DBUILD_QDMI_DOCS=OFF
cmake --build build --config Release --target qdmi_test

The target builds the example driver, example device, and template checks. All use the headers from this checkout; no separate QDMI installation is required.

Verify Discovery, Submission, and Results

Run the existing integration checks:

ctest --test-dir build -C Release --output-on-failure \

-R 'QDMIDriverLoadingTest|ClientVisibleDeviceIdIsStable|QueryDeviceProperties|JobLifecycle|GetHistogram'

CTest sets each test's working directory. The checks write their own local device configuration, load the bundled library, initialize sessions, and exercise the Client Interface. The checkpoint covers:

missing libraries, invalid configuration, duplicate IDs, and retry after a failed driver allocation;
discovering configured devices and querying their stable IDs and properties;
copying an OpenQASM 2 program into a job, submitting it, waiting, and checking the final status;
retrieving histogram keys and values for program index zero, checking their correspondence, and verifying that the counts sum to the requested shots.

Read-only sessions intentionally skip submission and result checks. The read/write cases must pass. To run all checks:

ctest --test-dir build -C Release --output-on-failure

The assertions and API calls are in test/test_qdmi.cpp, with session and configuration setup in test/utils/test_impl.cpp. These tests also run in QDMI's CI.

Follow the Application Workflow

An application talks to the driver through the QDMI Client Interface.

Allocate a QDMI_Session with QDMI_session_alloc, set the driver's supported session parameters, and call QDMI_session_init.
Query QDMI_SESSION_PROPERTY_DEVICES, then inspect each device's QDMI_DEVICE_PROPERTY_ID, capabilities, sites, and operations. The returned handles belong to this session.
Prepare a program in a supported format. Create a QDMI_Job with QDMI_device_create_job, set parameters such as QDMI_JOB_PARAMETER_SHOTSNUM, and call QDMI_job_set_programs. Even a single program is a list of length one. Text payload sizes include exactly one trailing null byte; binary payloads retain their bytes.
Submit with QDMI_job_submit, then use QDMI_job_check or QDMI_job_wait to follow execution. Check the terminal status before interpreting the available results. Read them with QDMI_job_get_results using the input program's index. Variable-size queries first request the required byte size, then fill an appropriately sized buffer.
Free the job with QDMI_job_free, then release the session with QDMI_session_free after its handles are no longer needed. Keep the driver library loaded throughout those lifetimes.

Check every return code. Supported formats, program counts, optional results, and authentication methods depend on the selected implementation. The mock's nonempty token selects read/write access; this is an example policy and needs no real credentials.

Diagnose Configuration and Loading Failures

The example driver reads QDMI_CONF, or qdmi.conf in the current working directory when the variable is unset. Each device line contains:

/path/to/libdevice.so PREFIX deployment.device-id

Use the platform's library suffix (.so, .dylib, or .dll), the implementation's exact symbol prefix, and a unique, nonempty ID. Relative library paths are resolved from the process's working directory. The example allows configuration files under the current working directory or the user's home directory after resolving symlinks. This format and path policy belong to the example driver; other drivers can choose different configuration.

Symptom	Check
Configuration cannot be opened or its path is rejected	Check QDMI_CONF, the working directory, file permissions, and the example's allowed configuration directories.
Device library cannot be loaded	Check its path, platform/architecture, and required shared-library dependencies.
Required symbol cannot be resolved	Check the symbol prefix and that the library implements the selected QDMI version.
Configuration is rejected	Supply exactly three fields per device line and unique IDs.
Session or job access is denied	Check the selected implementation's authentication and access policy. The mock requires a nonempty token for job creation.
A format, program count, query, or result is unsupported	Check capabilities and return codes; select a supported operation rather than assuming every optional feature is present.

Use trusted configuration files and libraries: loading a device library runs native code in the application process. For the ABI check and handle ownership, see the architecture.

Move to a Simulator or External Device

MQT Core's QDMI guides cover its runtime installation, local DDSIM execution, C++ and Python APIs, and SDK adapters. The QDMI execution tutorial walks through device discovery, compilation, submission, and result checks using the bundled DDSIM simulator. Its builtin driver supplies configured devices such as mqt.ddsim.default; manifest discovery and builtin_driver helpers are MQT Core conveniences. Follow its configuration guide for library registration and its Slurm guide for scheduler integration.

For Amazon Braket, IQM, or IBM, use the device project's installation and configuration guides for catalogues, endpoints, credentials, and deployment. Match the runtime and device versions before submitting work. Installing the standalone QDMI headers is not an additional runtime step when using a packaged application stack.