Cirq-Open Quantum Plugin

Beta. This plugin is in beta; its API and defaults may still change. Feedback is welcome in the Quantum Rings community.

A Cirq sampler that submits circuits to the Open Quantum platform. Write circuits with Cirq and run them on real quantum hardware.

How it works

Cirq exports OpenQASM natively (cirq.Circuit.to_qasm()), so this plugin does not depend on the Qiskit plugin. OpenQuantumSampler is a thin cirq.Sampler:

• OpenQuantumClient.from_env (Core SDK) handles authentication and backend discovery.
• Each resolved circuit is serialized to OpenQASM and submitted through the framework-agnostic SchedulerClient.
• Platform counts are reconstructed into cirq.Result objects.

Because it implements run_sweep, the standard cirq.Sampler methods — run, sample, run_sweep, and run_batch — all work.

Installation

# Plugin (and core SDK)
pip install openquantum-sdk-cirq

# or via extras:
pip install "openquantum-sdk[cirq]"

This pulls in cirq-core and openquantum-sdk.

Quick Start

import cirq
from cirq_openquantum import OpenQuantumSampler

sampler = OpenQuantumSampler(
    backend="ionq:forte-1",
    client_id="your_client_id",
    client_secret="your_client_secret",
)

q = cirq.LineQubit.range(2)
circuit = cirq.Circuit([
    cirq.H(q[0]),
    cirq.CNOT(q[0], q[1]),
    cirq.measure(*q, key="m"),
])

result = sampler.run(circuit, repetitions=1024)
print(result.histogram(key="m"))
# Counter({0: ~512, 3: ~512})   # 00 and 11

Circuits must contain at least one cirq.measure(...); the QASM exporter does not add measurements for you.

Authentication

Resolved in this order:

1. Pre-built client — pass client=OpenQuantumClient(...) for full control (saved accounts, custom URLs, keyring).
2. Bearer token — pass token= or set OPENQUANTUM_TOKEN.
3. Client credentials — pass client_id= + client_secret= or set OPENQUANTUM_CLIENT_ID + OPENQUANTUM_CLIENT_SECRET.

from_env() raises AuthenticationError when no credential resolves. The older OPENQUANTUM_*_BASE URL names are not read here; those remain an MCP-only fallback.

Configuration

Shots are set per run via repetitions and injected into configuration_data.

Backend-specific configuration

Some backends require extra fields. The free Quantum Rings simulator (qr:gpu-gb10) requires an engine:

sampler = OpenQuantumSampler(
    backend="qr:gpu-gb10",
    configuration_data={"engine": "amber_quantum_rings"},
)

Bit ordering

The platform returns counts little-endian (the first classical bit is the rightmost character, Qiskit-style), while Cirq is big-endian (the first measured qubit is the most-significant bit). The sampler reverses each bitstring by default (reverse_bits=True) so the mapping is correct, verified live against an asymmetric |10> state. Set reverse_bits=False only for a backend that returns counts big-endian.

License

Apache License 2.0