Qiskit OpenQASM 3 Importer

0.6.0 · active · verified Fri Apr 17

The `qiskit-qasm3-import` library provides functionality to parse OpenQASM 3 strings into Qiskit circuits, enabling interoperability between QASM 3 programs and the Qiskit ecosystem. It is currently at version 0.6.0 and releases new minor versions periodically, typically in conjunction with Qiskit's major releases or to add support for new QASM 3 features.

Common errors

```
ModuleNotFoundError: No module named 'qiskit_qasm3_import'
```
cause The `qiskit-qasm3-import` package is not installed in your Python environment.

fix Install the package using pip: `pip install qiskit-qasm3-import`
```
AttributeError: module 'qiskit_qasm3_import' has no attribute 'parse'
```
cause You are trying to call a function named `parse`, which does not exist. The correct function for parsing a QASM 3 string is `loads`.

fix Change `qiskit_qasm3_import.parse(...)` to `qiskit_qasm3_import.loads(...)`.
```
qiskit.exceptions.QiskitError: 'OpenQASM 3 circuits from this importer require Qiskit Terra >= 0.24.0 and < 1.0.0 for qiskit-qasm3-import < 0.6.0, or Qiskit >= 1.0.0 for qiskit-qasm3-import >= 0.6.0.'
```
cause There is a version mismatch between your installed `qiskit` and `qiskit-qasm3-import` packages. This error specifically points to the required compatibility.

fix If using Qiskit 1.0.0 or later, ensure `qiskit-qasm3-import` is version 0.6.0 or newer: `pip install --upgrade qiskit-qasm3-import`. If using an older Qiskit Terra, ensure `qiskit-qasm3-import` is compatible (typically <0.6.0).

Warnings

breaking Version 0.6.0 of `qiskit-qasm3-import` introduced compatibility with Qiskit 1.0.0. If you are using an older version of `qiskit-qasm3-import` (e.g., <0.6.0) with Qiskit 1.0.0+, you may encounter errors related to API changes or an incompatible `QuantumCircuit` object structure.
Fix: Upgrade to `qiskit-qasm3-import>=0.6.0` when using Qiskit 1.0.0 or later: `pip install --upgrade qiskit-qasm3-import`.
gotcha The `qiskit-qasm3-import` library does not currently support all features defined by the OpenQASM 3 specification. Complex or less common QASM 3 constructs might lead to parsing errors or incomplete circuit representations.
Fix: Refer to the official documentation and GitHub repository for the list of currently supported OpenQASM 3 features. For unsupported features, consider simplifying your QASM 3 code or reporting an issue to the project.
gotcha The `loads` function expects a string as input. Providing a file path or an object that is not a string will result in a `TypeError` or a parsing failure.
Fix: Ensure that the input to `qiskit_qasm3_import.loads()` is a valid string containing the OpenQASM 3 code. To load from a file, read the file content into a string first (e.g., `with open('my_circuit.qasm', 'r') as f: qasm_str = f.read()`).

Install

pip install qiskit-qasm3-import Install latest version

Imports

loads
```
from qiskit_qasm3_import import loads
```

Quickstart

Parse an OpenQASM 3 string into a Qiskit `QuantumCircuit` object using the `loads` function.

from qiskit_qasm3_import import loads

qasm3_str = """
OPENQASM 3.0;
include "qelib1.inc";
qreg q[2];
creg c[2];
h q[0];
cx q[0], q[1];
measure q -> c;
"""

# Parse the QASM 3 string into a Qiskit QuantumCircuit
circuit = loads(qasm3_str)

# Print a summary of the resulting circuit
print(circuit.draw('text', idle_wires=False))

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