Configure and cache the GuoJi Quantum cloud account credentials.

The api_key is persisted to ~/.gjq_client/gjq_client_account.json for reuse.

SECURITY: the api_key is passed as a tool argument, so it can end up in the LLM context and in client/transport logs. Prefer setting the GJQ_API_KEY environment variable; use this tool only in a trusted local setup.

Get the currently configured account info (api_key masked).

List all available quantum backends (devices/simulators).

Get the static configuration of a backend (basis gates, n_qubits, etc.).

Get calibration properties of a backend (T1/T2, gate errors). May be null.

Return the name of the least busy available backend.

Submit a sampling task. Provide the circuit as an OpenQASM 2.0 string (OpenQASM 3 also works if the optional qiskit_qasm3_import is installed).

Returns a task_id; poll get_task_status_tool then get_task_result_tool. SAS-CPU simulator requires amplitude_index.

Submit an expectation-estimation task.

observable is a list like [["ZZ", 1.0], ["XX", 0.5]] (Pauli string + coeff). Returns a task_id; fetch results with get_task_result_tool(task_id, observable).

Get task status: INITIALIZING / QUEUED / RUNNING / DONE / ERROR / CANCELLED.

Get the result of a task.

While the task is still running the result is empty and pending is true; check task_status to see the current state. Pass observable (same format as estimate_tool) to compute expectation values.

Get the execution log of a task.

Get task details (backend, shots, submit time).

List the current user's tasks.