get num of qubits from api or use 36 and fix EM sampler

qiskit_ionq/helpers.py

@@ -34,6 +34,9 @@
 import base64
 import platform
 import warnings
+import os
+import requests
+from dotenv import dotenv_values
 
 from qiskit import __version__ as qiskit_terra_version
 from qiskit.circuit import controlledgate as q_cgates
@@ -423,7 +426,7 @@ def qiskit_to_ionq(
     settings = passed_args.get("job_settings") or None
     if settings is not None:
         ionq_json["settings"] = settings
-    error_mitigation = passed_args.get("error_mitigation")
+    error_mitigation = passed_args.get("error_mitigation") or backend.options.error_mitigation
     if error_mitigation and isinstance(error_mitigation, ErrorMitigation):
         ionq_json["error_mitigation"] = error_mitigation.value
     return json.dumps(ionq_json, cls=SafeEncoder)
@@ -474,6 +477,73 @@ def default(self, o):
         return "unknown"
 
 
+
+def resolve_credentials(token: str = None, url: str = None):
+    """Resolve credentials for use in IonQ API calls.
+
+    If the provided ``token`` and ``url`` are both ``None``, then these values
+    are loaded from the ``IONQ_API_TOKEN`` and ``IONQ_API_URL``
+    environment variables, respectively.
+
+    If no url is discovered, then ``https://api.ionq.co/v0.3`` is used.
+
+    Args:
+        token (str): IonQ API access token.
+        url (str, optional): IonQ API url. Defaults to ``None``.
+
+    Returns:
+        dict[str]: A dict with "token" and "url" keys, for use by a client.
+    """
+    env_token = (
+        dotenv_values().get("QISKIT_IONQ_API_TOKEN")  # first check for dotenv values
+        or dotenv_values().get("IONQ_API_KEY")
+        or dotenv_values().get("IONQ_API_TOKEN")
+        or os.getenv("QISKIT_IONQ_API_TOKEN")  # then check for global env values
+        or os.getenv("IONQ_API_KEY")
+        or os.getenv("IONQ_API_TOKEN")
+    )
+    env_url = (
+        dotenv_values().get("QISKIT_IONQ_API_URL")
+        or dotenv_values().get("IONQ_API_URL")
+        or os.getenv("QISKIT_IONQ_API_URL")
+        or os.getenv("IONQ_API_URL")
+    )
+    return {
+        "token": token or env_token,
+        "url": url or env_url or "https://api.ionq.co/v0.3",
+    }
+
+
+
+def get_n_qubits(backend: str) -> int:
+    """Get the number of qubits for a given backend.
+
+    Args:
+        backend (str): The name of the backend.
+
+    Returns:
+        int: The number of qubits for the backend.
+    """
+    url, token = resolve_credentials().values()
+    try:
+        return requests.get(
+            url=f"{url}/characterizations/backends/{backend}/current",
+            headers={"Authorization": f"apiKey {token}"},
+            timeout=5,
+        ).json()["qubits"]
+    except Exception:  # pylint: disable=broad-except
+        if backend == "ionq_qpu.harmony":
+            return 11
+        elif backend == "ionq_qpu.aria-1":
+            return 25
+        elif backend == "ionq_qpu.aria-2":
+            return 25
+        elif backend == "ionq_qpu.forte-1":
+            return 36
+        else:
+            return 36
+
+
 __all__ = [
     "qiskit_to_ionq",
     "qiskit_circ_to_ionq_circ",

qiskit_ionq/ionq_backend.py

@@ -31,12 +31,12 @@
 import warnings
 
 from qiskit.providers import BackendV1 as Backend
-from qiskit.providers.models import BackendConfiguration
+from qiskit.providers.models.backendconfiguration import BackendConfiguration
 from qiskit.providers.models.backendstatus import BackendStatus
 from qiskit.providers import Options
 
 from . import exceptions, ionq_client, ionq_job, ionq_equivalence_library
-from .helpers import GATESET_MAP
+from .helpers import GATESET_MAP, get_n_qubits
 
 
 class Calibration:
@@ -407,7 +407,7 @@ def __init__(self, provider, name="simulator", gateset="qis"):
                 "basis_gates": GATESET_MAP[gateset],
                 "memory": False,
                 # Varied based on noise model, but enforced server-side.
-                "n_qubits": 35,
+                "n_qubits": get_n_qubits(name),
                 "conditional": False,
                 "max_shots": 1,
                 "max_experiments": 1,
@@ -482,7 +482,7 @@ def __init__(self, provider, name="ionq_qpu", gateset="qis"):
                 # This is a generic backend for all IonQ hardware, the server will do more specific
                 # qubit count checks. In the future, dynamic backend configuration from the server
                 # will be used in place of these hard-coded caps.
-                "n_qubits": 35,
+                "n_qubits": get_n_qubits(name),
                 "conditional": False,
                 "max_shots": 10000,
                 "max_experiments": 1,

qiskit_ionq/ionq_provider.py

@@ -27,52 +27,16 @@
 """Provider for interacting with IonQ backends"""
 
 import logging
-import os
-from dotenv import dotenv_values
 
 from qiskit.providers.exceptions import QiskitBackendNotFoundError
 from qiskit.providers.providerutils import filter_backends
+from .helpers import resolve_credentials
 
 from . import ionq_backend
 
 logger = logging.getLogger(__name__)
 
 
-def resolve_credentials(token: str = None, url: str = None):
-    """Resolve credentials for use in IonQ Client API calls.
-
-    If the provided ``token`` and ``url`` are both ``None``, then these values
-    are loaded from the ``IONQ_API_TOKEN`` and ``IONQ_API_URL``
-    environment variables, respectively.
-
-    If no url is discovered, then ``https://api.ionq.co/v0.3`` is used.
-
-    Args:
-        token (str): IonQ API access token.
-        url (str, optional): IonQ API url. Defaults to ``None``.
-
-    Returns:
-        dict[str]: A dict with "token" and "url" keys, for use by a client.
-    """
-    env_token = (
-        dotenv_values().get("QISKIT_IONQ_API_TOKEN")  # first check for dotenv values
-        or dotenv_values().get("IONQ_API_KEY")
-        or dotenv_values().get("IONQ_API_TOKEN")
-        or os.getenv("QISKIT_IONQ_API_TOKEN")  # then check for global env values
-        or os.getenv("IONQ_API_KEY")
-        or os.getenv("IONQ_API_TOKEN")
-    )
-    env_url = (
-        dotenv_values().get("QISKIT_IONQ_API_URL")
-        or dotenv_values().get("IONQ_API_URL")
-        or os.getenv("QISKIT_IONQ_API_URL")
-        or os.getenv("IONQ_API_URL")
-    )
-    return {
-        "token": token or env_token,
-        "url": url or env_url or "https://api.ionq.co/v0.3",
-    }
-
 
 class IonQProvider:
     """Provider for interacting with IonQ backends

qiskit_ionq/version.py

@@ -34,7 +34,7 @@
 pkg_parent = pathlib.Path(__file__).parent.parent.absolute()
 
 # major, minor, patch
-VERSION_INFO = ".".join(map(str, (0, 5, 4)))
+VERSION_INFO = ".".join(map(str, (0, 5, 5)))
 
 
 def _minimal_ext_cmd(cmd: List[str]) -> bytes:

test/conftest.py

@@ -27,7 +27,7 @@
 """global pytest fixtures"""
 import pytest
 import requests_mock as _requests_mock
-from qiskit.providers import models as q_models
+from qiskit.providers.models.backendconfiguration import BackendConfiguration
 from requests_mock import adapter as rm_adapter
 
 from qiskit_ionq import ionq_backend, ionq_job, ionq_provider
@@ -43,7 +43,7 @@ def gateset(self):
     def __init__(
         self, provider, name="ionq_mock_backend"
     ):  # pylint: disable=redefined-outer-name
-        config = q_models.BackendConfiguration.from_dict(
+        config = BackendConfiguration.from_dict(
             {
                 "backend_name": name,
                 "backend_version": "0.0.1",

test/ionq_backend/test_base_backend.py

@@ -227,8 +227,7 @@ def test_warn_null_mappings(mock_backend, requests_mock):
 
     with pytest.warns(UserWarning) as warninfo:
         mock_backend.run(qc)
-    assert len(warninfo) == 1
-    assert str(warninfo[-1].message) == "Circuit is not measuring any qubits"
+    assert "Circuit is not measuring any qubits" in {str(w.message) for w in warninfo}
 
 
 def test_multiexp_job(mock_backend, requests_mock):