Merge branch 'master' into dependabot/pip/urllib3-1.26.18

CHANGELOG.md

@@ -2,8 +2,24 @@
 
 ### New features since last release
 
+* Application of debiasing and sharpening for error mitigation is made available, with parameters set on device initialization. Error mitigation strategies that 
+  need to be set at runtime are defined in the `error_mitigation` dictionary (currently a single strategy, `debias`, is available). Whether or not to
+  apply sharpening to the returned results is set via the parameter `sharpen`. A device using debiasing and sharpening to mitigate errors can be initialized as:
+
+  ```python
+  import pennylane as qml
+
+  dev = qml.device("ionq.qpu", wires=2, error_mitigation={"debias": True}, sharpen=True)
+  ```
+
+  For more details, see the [IonQ Guide on sharpening and debiasing](https://ionq.com/resources/debiasing-and-sharpening), or refer to the publication <https://arxiv.org/pdf/2301.07233.pdf>
+  [(#75)](https://github.com/PennyLaneAI/PennyLane-IonQ/pull/75)
+
 ### Improvements 🛠
 
+* The IonQ API version accessed via the plugin is updated from 0.1 to 0.3
+  [(#75)](https://github.com/PennyLaneAI/PennyLane-IonQ/pull/75)
+
 * Use new `backend` field to specify `qpu`.
   [(#81)](https://github.com/PennyLaneAI/PennyLane-IonQ/pull/81)
 
@@ -20,6 +36,7 @@
 This release contains contributions from (in alphabetical order):
 
 Spencer Churchill
+Lillian Frederiksen
 
 ---
 # Release 0.32.0

doc/devices.rst

@@ -4,18 +4,17 @@ IonQ Devices
 The PennyLane-IonQ plugin provides the ability for PennyLane to access
 devices available via IonQ's online API.
 
-Currently, access is available to two remote devices: an ideal and
-a noisy trapped-ion simulator.
+Currently, access is available to two remote devices: one to access an ideal
+trapped-ion simulator and another to access to IonQ's trapped-ion QPUs.
 
 .. raw::html
     <section id="simulator">
 
 Ideal trapped-ion simulator
 ------------------------
 
-This device provides an ideal noiseless trapped-ion simulation.
-Once the plugin has been installed, you can use this device
-directly in PennyLane by specifying ``"ionq.simulator"``:
+The :class:`~.pennylane_ionq.SimulatorDevice` provides an ideal noiseless trapped-ion simulation.
+Once the plugin has been installed, you can use this device directly in PennyLane by specifying ``"ionq.simulator"``:
 
 .. code-block:: python
 
@@ -38,9 +37,8 @@ directly in PennyLane by specifying ``"ionq.simulator"``:
 Trapped-Ion QPU
 ---------------
 
-This device provides access to IonQ's trapped-ion QPUs.
-Once the plugin has been installed, you can use this device
-directly in PennyLane by specifying ``"ionq.qpu"`` with a
+The :class:`~.pennylane_ionq.QPUDevice` provides access to IonQ's trapped-ion QPUs. Once the plugin has been
+installed, you can use this device directly in PennyLane by specifying ``"ionq.qpu"`` with a
 ``"backend"`` from `available backends <https://docs.ionq.com/#tag/jobs>`_:
 
 .. code-block:: python

pennylane_ionq/api_client.py

@@ -112,12 +112,16 @@ class APIClient:
         api_key (str): IonQ cloud platform API key
     """
 
-    USER_AGENT = "pennylane-ionq-api-client/0.1"
-    HOSTNAME = "api.ionq.co/v0.1"
+    USER_AGENT = "pennylane-ionq-api-client/0.3"
+    HOSTNAME = "api.ionq.co/v0.3"
     BASE_URL = "https://{}".format(HOSTNAME)
 
     def __init__(self, **kwargs):
-        self.AUTHENTICATION_TOKEN = os.getenv("IONQ_API_KEY") or kwargs.get("api_key", None)
+        self.AUTHENTICATION_TOKEN = (
+            kwargs.get("api_key", None)
+            or os.getenv("PENNYLANE_IONQ_API_KEY")
+            or os.getenv("IONQ_API_KEY")
+        )
         self.DEBUG = False
 
         if "IONQ_DEBUG" in os.environ:
@@ -196,17 +200,18 @@ def request(self, method, **params):
 
         return response
 
-    def get(self, path):
+    def get(self, path, params=None):
         """
         Sends a GET request to the provided path. Returns a response object.
 
         Args:
             path (str): path to send the GET request to
+            params (dict): parameters to include in the request
 
         Returns:
             requests.Response: A response object, or None if no response could be fetched
         """
-        return self.request(requests.get, url=self.join_path(path))
+        return self.request(requests.get, url=self.join_path(path), params=params)
 
     def post(self, path, payload):
         """
@@ -249,7 +254,7 @@ def join_path(self, path):
         """
         return join_path(self.resource.PATH, path)
 
-    def get(self, resource_id=None):
+    def get(self, resource_id=None, params=None):
         """
         Attempts to retrieve a particular record by sending a GET
         request to the appropriate endpoint. If successful, the resource
@@ -262,9 +267,9 @@ def get(self, resource_id=None):
             raise MethodNotSupportedException("GET method on this resource is not supported")
 
         if resource_id is not None:
-            response = self.client.get(self.join_path(str(resource_id)))
+            response = self.client.get(self.join_path(str(resource_id)), params=params)
         else:
-            response = self.client.get(self.resource.PATH)
+            response = self.client.get(self.resource.PATH, params=params)
         self.handle_response(response)
 
     def create(self, **params):

pennylane_ionq/device.py

@@ -14,7 +14,7 @@
 """
 This module contains the device class for constructing IonQ devices for PennyLane.
 """
-import os, warnings
+import warnings
 from time import sleep
 
 import numpy as np
@@ -63,16 +63,27 @@ class IonQDevice(QubitDevice):
     r"""IonQ device for PennyLane.
 
     Args:
-        target (str): the target device, either ``"simulator"`` or ``"qpu"``
         wires (int or Iterable[Number, str]]): Number of wires to initialize the device with,
             or iterable that contains unique labels for the subsystems as numbers (i.e., ``[-1, 0, 2]``)
             or strings (``['ancilla', 'q1', 'q2']``).
-        gateset (str): the target gateset, either ``"qis"`` or ``"native"``.
+
+    Kwargs:
+        target (str): the target device, either ``"simulator"`` or ``"qpu"``. Defaults to ``simulator``.
+        gateset (str): the target gateset, either ``"qis"`` or ``"native"``. Defaults to ``qis``.
         shots (int, list[int]): Number of circuit evaluations/random samples used to estimate
-            expectation values of observables.
+            expectation values of observables. Defaults to 1024.
             If a list of integers is passed, the circuit evaluations are batched over the list of shots.
         api_key (str): The IonQ API key. If not provided, the environment
             variable ``IONQ_API_KEY`` is used.
+        error_mitigation (dict): settings for error mitigation when creating a job. Defaults to None.
+            Not available on all backends. Set by default on some hardware systems. See
+            `IonQ API Job Creation <https://docs.ionq.com/#tag/jobs/operation/createJob>`_  and
+            `IonQ Debiasing and Sharpening <https://ionq.com/resources/debiasing-and-sharpening>`_ for details.
+            Valid keys include: ``debias`` (bool).
+        sharpen (bool): whether to use sharpening when accessing the results of an executed job. Defaults to None
+            (no value passed at job retrieval). Will generally return more accurate results if your expected output
+            distribution has peaks. See `IonQ Debiasing and Sharpening
+            <https://ionq.com/resources/debiasing-and-sharpening>`_ for details.
     """
     # pylint: disable=too-many-instance-attributes
     name = "IonQ PennyLane plugin"
@@ -91,14 +102,26 @@ class IonQDevice(QubitDevice):
     # and therefore does not support the Hermitian observable.
     observables = {"PauliX", "PauliY", "PauliZ", "Hadamard", "Identity"}
 
-    def __init__(self, wires, *, target="simulator", gateset="qis", shots=1024, api_key=None):
+    def __init__(
+        self,
+        wires,
+        *,
+        target="simulator",
+        gateset="qis",
+        shots=1024,
+        api_key=None,
+        error_mitigation=None,
+        sharpen=False,
+    ):
         if shots is None:
             raise ValueError("The ionq device does not support analytic expectation values.")
 
         super().__init__(wires=wires, shots=shots)
         self.target = target
         self.api_key = api_key
         self.gateset = gateset
+        self.error_mitigation = error_mitigation
+        self.sharpen = sharpen
         self._operation_map = _GATESET_OPS[gateset]
         self.reset()
 
@@ -107,16 +130,25 @@ def reset(self):
         self._prob_array = None
         self.histogram = None
         self.circuit = {
+            "format": "ionq.circuit.v0",
             "qubits": self.num_wires,
             "circuit": [],
             "gateset": self.gateset,
         }
         self.job = {
-            "lang": "json",
-            "body": self.circuit,
+            "input": self.circuit,
             "target": self.target,
             "shots": self.shots,
         }
+        if self.error_mitigation is not None:
+            self.job["error_mitigation"] = self.error_mitigation
+        if self.job["target"] == "qpu":
+            self.job["target"] = "qpu.harmony"
+            warnings.warn(
+                "The ionq_qpu backend is deprecated. Defaulting to ionq_qpu.harmony.",
+                UserWarning,
+                stacklevel=2,
+            )
 
     @property
     def operations(self):
@@ -190,7 +222,9 @@ def _submit_job(self):
             if job.is_failed:
                 raise JobExecutionError("Job failed")
 
-        job.manager.get(job.id.value)
+        params = {} if self.sharpen is None else {"sharpen": self.sharpen}
+
+        job.manager.get(resource_id=job.id.value, params=params)
 
         # The returned job histogram is of the form
         # dict[str, float], and maps the computational basis
@@ -242,19 +276,26 @@ class SimulatorDevice(IonQDevice):
         wires (int or Iterable[Number, str]]): Number of wires to initialize the device with,
             or iterable that contains unique labels for the subsystems as numbers (i.e., ``[-1, 0, 2]``)
             or strings (``['ancilla', 'q1', 'q2']``).
-        gateset (str): the target gateset, either ``"qis"`` or ``"native"``.
-        shots (int, list[int]): Number of circuit evaluations/random samples used to estimate
+        gateset (str): the target gateset, either ``"qis"`` or ``"native"``. Defaults to ``qis``.
+        shots (int, list[int], None): Number of circuit evaluations/random samples used to estimate
             expectation values of observables. If ``None``, the device calculates probability, expectation values,
             and variances analytically. If an integer, it specifies the number of samples to estimate these quantities.
             If a list of integers is passed, the circuit evaluations are batched over the list of shots.
+            Defaults to 1024.
         api_key (str): The IonQ API key. If not provided, the environment
             variable ``IONQ_API_KEY`` is used.
     """
     name = "IonQ Simulator PennyLane plugin"
     short_name = "ionq.simulator"
 
-    def __init__(self, wires, *, target="simulator", gateset="qis", shots=1024, api_key=None):
-        super().__init__(wires=wires, target=target, gateset=gateset, shots=shots, api_key=api_key)
+    def __init__(self, wires, *, gateset="qis", shots=1024, api_key=None):
+        super().__init__(
+            wires=wires,
+            target="simulator",
+            gateset=gateset,
+            shots=shots,
+            api_key=api_key,
+        )
 
     def generate_samples(self):
         """Generates samples by random sampling with the probabilities returned by the simulator."""
@@ -270,14 +311,23 @@ class QPUDevice(IonQDevice):
         wires (int or Iterable[Number, str]]): Number of wires to initialize the device with,
             or iterable that contains unique labels for the subsystems as numbers (i.e., ``[-1, 0, 2]``)
             or strings (``['ancilla', 'q1', 'q2']``).
-        gateset (str): the target gateset, either ``"qis"`` or ``"native"``.
+        gateset (str): the target gateset, either ``"qis"`` or ``"native"``. Defaults to ``qis``.
         backend (str): Optional specifier for an IonQ backend. Can be ``"harmony"``, ``"aria-1"``, etc.
+            Default to ``harmony``.
         shots (int, list[int]): Number of circuit evaluations/random samples used to estimate
-            expectation values of observables. If ``None``, the device calculates probability, expectation values,
-            and variances analytically. If an integer, it specifies the number of samples to estimate these quantities.
-            If a list of integers is passed, the circuit evaluations are batched over the list of shots.
+            expectation values of observables. Defaults to 1024. If a list of integers is passed, the
+            circuit evaluations are batched over the list of shots.
         api_key (str): The IonQ API key. If not provided, the environment
             variable ``IONQ_API_KEY`` is used.
+        error_mitigation (dict): settings for error mitigation when creating a job. Defaults to None.
+            Not available on all backends. Set by default on some hardware systems. See
+            `IonQ API Job Creation <https://docs.ionq.com/#tag/jobs/operation/createJob>`_  and
+            `IonQ Debiasing and Sharpening <https://ionq.com/resources/debiasing-and-sharpening>`_ for details.
+            Valid keys include: ``debias`` (bool).
+        sharpen (bool): whether to use sharpening when accessing the results of an executed job.
+            Defaults to None (no value passed at job retrieval). Will generally return more accurate results if
+            your expected output distribution has peaks. See `IonQ Debiasing and Sharpening
+            <https://ionq.com/resources/debiasing-and-sharpening>`_ for details.
     """
     name = "IonQ QPU PennyLane plugin"
     short_name = "ionq.qpu"
@@ -286,12 +336,14 @@ def __init__(
         self,
         wires,
         *,
-        target="qpu",
-        backend=None,
         gateset="qis",
         shots=1024,
+        backend="harmony",
+        error_mitigation=None,
+        sharpen=None,
         api_key=None,
     ):
+        target = "qpu"
         self.backend = backend
         if self.backend is not None:
             target += "." + self.backend
@@ -301,6 +353,8 @@ def __init__(
             gateset=gateset,
             shots=shots,
             api_key=api_key,
+            error_mitigation=error_mitigation,
+            sharpen=sharpen,
         )
 
     def generate_samples(self):

tests/conftest.py

@@ -36,9 +36,7 @@
 U2 = np.array([[0, 1, 1, 1], [1, 0, 1, -1], [1, -1, 0, 1], [1, 1, -1, 0]]) / np.sqrt(3)
 
 # single qubit Hermitian observable
-A = np.array(
-    [[1.02789352, 1.61296440 - 0.3498192j], [1.61296440 + 0.3498192j, 1.23920938 + 0j]]
-)
+A = np.array([[1.02789352, 1.61296440 - 0.3498192j], [1.61296440 + 0.3498192j, 1.23920938 + 0j]])
 
 
 # ==========================================================