# iqm.qdmi.serializers

Serialization of Qiskit circuits into the IQM JSON program format.

MQT Core loads [`qiskit_to_iqm_json()`](#iqm.qdmi.serializers.qiskit_to_iqm_json) through the
`mqt.core.qiskit.program_serializers` entry point, so any QDMI backend over an
IQM device submits IQM JSON without naming this package.

## Module Contents

### qiskit_to_iqm_json(circuit: [QuantumCircuit](https://quantum.cloud.ibm.com/docs/api/qiskit/qiskit.circuit.QuantumCircuit), backend: [QDMIBackend](https://mqt.readthedocs.io/projects/core/en/stable/api/mqt/core/plugins/qiskit/backend/index.html#mqt.core.plugins.qiskit.backend.QDMIBackend)) → [str](https://docs.python.org/3/builtins/stdtypes.html#str)

Serialize a Qiskit [`QuantumCircuit`](https://quantum.cloud.ibm.com/docs/api/qiskit/qiskit.circuit.QuantumCircuit) into IQM JSON.

The IQM JSON format is a device-specific format that encodes quantum operations
as JSON objects with site names, operation names, and arguments. Circuit
metadata is preserved using Python’s JSON encoding (including tuples as
arrays), with string object keys and finite numbers required at every level.
Metadata that cannot be encoded is dropped with a warning; the circuit and
its metadata are not modified.

#### NOTE
The serialization currently supports only operations that are natively
supported by the IQM hardware. Unsupported operations will raise
[`UnsupportedOperationError`](https://mqt.readthedocs.io/projects/core/en/stable/api/mqt/core/plugins/qiskit/exceptions/index.html#mqt.core.plugins.qiskit.exceptions.UnsupportedOperationError).

* **Parameters:**
  * **circuit** – The Qiskit quantum circuit to serialize.
  * **backend** – The backend that runs the circuit. Its device provides the site
    names the format uses as loci. For [`IQMBackend`](../qiskit/index.html.md#iqm.qdmi.qiskit.IQMBackend),
    circuit indices follow the calibrated target’s site order.
* **Returns:**
  JSON string representation of the circuit in IQM format.
* **Raises:**
  * **UnsupportedOperationError** – If the circuit contains operations not supported
    by IQM hardware.
  * **TranslationError** – If the serialization fails.

### Examples

```pycon
>>> from qiskit import QuantumCircuit
>>> import numpy as np
>>> from iqm.qdmi.serializers import qiskit_to_iqm_json
>>> qc = QuantumCircuit(2, 2)
>>> qc.r(np.pi / 2, 0, 0)
>>> qc.cz(0, 1)
>>> qc.measure_all()
>>> json_str = qiskit_to_iqm_json(qc, backend)
```