Add mixers to hyper_params_factory (#303)

* add mixers to hyper_params_factory * [pre-commit.ci] auto fixes from pre-commit.com hooks * add missing imports * ..math annotation * use raw strings * Update pyriemann_qiskit/utils/hyper_params_factory.py Co-authored-by: Quentin Barthélemy <q.barthelemy@gmail.com> * Update pyriemann_qiskit/utils/hyper_params_factory.py Co-authored-by: Quentin Barthélemy <q.barthelemy@gmail.com> * Update pyriemann_qiskit/utils/hyper_params_factory.py Co-authored-by: Quentin Barthélemy <q.barthelemy@gmail.com> * Update pyriemann_qiskit/utils/hyper_params_factory.py Co-authored-by: Quentin Barthélemy <q.barthelemy@gmail.com> --------- Co-authored-by: Gregoire Cattan <gregoire.cattan@ibm.com> Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com> Co-authored-by: Quentin Barthélemy <q.barthelemy@gmail.com>
pyRiemann · Sep 6, 2024 · 6aa64d2 · 6aa64d2
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diff --git a/doc/api.rst b/doc/api.rst
@@ -90,6 +90,9 @@ Hyper-parameters generation
     gen_two_local
     get_spsa
     get_spsa_parameters
+    create_mixer_rotational_X_gates
+    create_mixer_rotational_XY_gates
+    create_mixer_rotational_XZ_gates
 
 Preprocessing
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~

diff --git a/examples/toys_dataset/plot_qaoa_cv.py b/examples/toys_dataset/plot_qaoa_cv.py
@@ -18,60 +18,16 @@
 
 from docplex.mp.model import Model
 import matplotlib.pyplot as plt
-from qiskit.circuit import QuantumCircuit, QuantumRegister
+from pyriemann_qiskit.utils.hyper_params_factory import (
+    create_mixer_rotational_X_gates,
+    create_mixer_rotational_XY_gates,
+    create_mixer_rotational_XZ_gates,
+)
 from qiskit.primitives import BackendSampler
 from qiskit_aer import AerSimulator
 from qiskit_algorithms.optimizers import COBYLA, SPSA
 from pyriemann_qiskit.utils.docplex import QAOACVOptimizer
 
-###############################################################################
-# Define mixer operators
-#
-# QAOA is a quantum circuit that is a repetition of
-# a cost an mixer operator.
-#
-# We will use some of the mixer operators defined in [1]_.
-#
-
-
-def create_mixer_rotational_X_gates(angle):
-    def mixer_X(n_qubits):
-        qr = QuantumRegister(n_qubits)
-        mixer = QuantumCircuit(qr)
-
-        for i in range(n_qubits):
-            mixer.rx(angle, qr[i])
-
-    return mixer_X
-
-
-def create_mixer_rotational_XY_gates(angle):
-    def mixer_XY(n_qubits):
-        qr = QuantumRegister(n_qubits)
-        mixer = QuantumCircuit(qr)
-
-        for i in range(n_qubits - 1):
-            mixer.rx(angle, qr[i])
-            mixer.rx(angle, qr[i + 1])
-            mixer.ry(angle, qr[i])
-            mixer.ry(angle, qr[i + 1])
-
-    return mixer_XY
-
-
-def create_mixer_rotational_XZ_gates(angle):
-    def mixer_XZ(n_qubits):
-        qr = QuantumRegister(n_qubits)
-        mixer = QuantumCircuit(qr)
-
-        for i in range(1, n_qubits - 1):
-            mixer.rz(angle, qr[i - 1])
-            mixer.rx(angle, qr[i])
-            mixer.rx(angle + math.pi / 2, qr[i])
-            mixer.rz(angle, qr[i + 1])
-
-    return mixer_XZ
-
 
 ###############################################################################
 # Run QAOA-CV
@@ -121,6 +77,9 @@ def run_qaoa_cv(n_reps, optimizer, create_mixer):
 ###############################################################################
 # Hyper-parameters
 #
+# QAOA is a quantum circuit that is a repetition of
+# a cost an mixer operator.
+#
 # We will now try different combination of optimizer and mixers.
 #
 

diff --git a/pyriemann_qiskit/utils/__init__.py b/pyriemann_qiskit/utils/__init__.py
@@ -7,6 +7,7 @@
     square_bin_mat_var,
     ClassicalOptimizer,
     NaiveQAOAOptimizer,
+    QAOACVOptimizer,
     set_global_optimizer,
     get_global_optimizer,
 )
@@ -36,6 +37,7 @@
     "square_bin_mat_var",
     "ClassicalOptimizer",
     "NaiveQAOAOptimizer",
+    "QAOACVOptimizer",
     "set_global_optimizer",
     "get_global_optimizer",
     "distance",

diff --git a/pyriemann_qiskit/utils/hyper_params_factory.py b/pyriemann_qiskit/utils/hyper_params_factory.py
@@ -1,7 +1,14 @@
-from qiskit.circuit.library import ZZFeatureMap, ZFeatureMap, PauliFeatureMap
-from qiskit_algorithms.optimizers import SPSA
-from qiskit.circuit.library import TwoLocal
 import inspect
+import math
+
+from qiskit.circuit import QuantumCircuit, QuantumRegister
+from qiskit.circuit.library import (
+    ZZFeatureMap,
+    ZFeatureMap,
+    PauliFeatureMap,
+    TwoLocal,
+)
+from qiskit_algorithms.optimizers import SPSA
 
 
 def gen_x_feature_map(reps=2):
@@ -335,3 +342,123 @@ def get_spsa_parameters(spsa):
         signature.parameters["gamma"].default,
         signature.parameters["stability_constant"].default,
     )
+
+
+def create_mixer_rotational_X_gates(angle):
+    r"""Return the default mixing operator with QAOA.
+
+    .. math::
+        H_X = \sum_{i}^{N} X_i
+
+    See [1]_ for details.
+
+    Parameters
+    ----------
+    angle : float
+        The angle of the gates' rotation.
+
+    Returns
+    -------
+    mixer : QuantumCircuit
+        The mixer.
+
+    Notes
+    -----
+    .. versionadded:: 0.4.0
+
+    References
+    ----------
+    .. [1] \
+        https://dice.cyfronet.pl/papers/JPlewa_JSienko_msc_v2.pdf
+    """
+
+    def mixer_X(n_qubits):
+        qr = QuantumRegister(n_qubits)
+        mixer = QuantumCircuit(qr)
+
+        for qr_ in qr:
+            mixer.rx(angle, qr_)
+
+    return mixer_X
+
+
+def create_mixer_rotational_XY_gates(angle):
+    r"""Return the XY mixer.
+
+    .. math::
+        H_{XY} = \sum_{i}^{N-1} \left( X_i X_{i+1} + Y_i Y_{i+1} \right),
+
+    See [1]_ for details.
+
+    Parameters
+    ----------
+    angle : float
+        The angle of the gates' rotation.
+
+    Returns
+    -------
+    mixer : QuantumCircuit
+        The mixer.
+
+    Notes
+    -----
+    .. versionadded:: 0.4.0
+
+    References
+    ----------
+    .. [1] \
+        https://dice.cyfronet.pl/papers/JPlewa_JSienko_msc_v2.pdf
+    """
+
+    def mixer_XY(n_qubits):
+        qr = QuantumRegister(n_qubits)
+        mixer = QuantumCircuit(qr)
+
+        for i in range(n_qubits - 1):
+            mixer.rx(angle, qr[i])
+            mixer.rx(angle, qr[i + 1])
+            mixer.ry(angle, qr[i])
+            mixer.ry(angle, qr[i + 1])
+
+    return mixer_XY
+
+
+def create_mixer_rotational_XZ_gates(angle):
+    r"""Return a mixing operator with XZ gates.
+
+    .. math::
+        H_{\text{mix}} = \sum_{i}^{N-1} \left( Z_{i-1} X_i - X_i Z_{i+1} \right).
+
+    See [1]_ for details.
+
+    Parameters
+    ----------
+    angle : float
+        The angle of the gates' rotation.
+
+    Returns
+    -------
+    mixer : QuantumCircuit
+        The mixer.
+
+    Notes
+    -----
+    .. versionadded:: 0.4.0
+
+    References
+    ----------
+    .. [1] \
+        https://dice.cyfronet.pl/papers/JPlewa_JSienko_msc_v2.pdf
+    """
+
+    def mixer_XZ(n_qubits):
+        qr = QuantumRegister(n_qubits)
+        mixer = QuantumCircuit(qr)
+
+        for i in range(1, n_qubits - 1):
+            mixer.rz(angle, qr[i - 1])
+            mixer.rx(angle, qr[i])
+            mixer.rx(angle + math.pi / 2, qr[i])
+            mixer.rz(angle, qr[i + 1])
+
+    return mixer_XZ