Merge dev into master and delete dev (#1257)

As name says. Once this PR is merged, `dev` will be deleted either
automatically on merge, or manually if not.

---------

Co-authored-by: GitHub Nightly Merge Action <actions@github.com>
Co-authored-by: Mikhail Andrenkov <mikhail@xanadu.ai>
Co-authored-by: David Wierichs <davidwierichs@gmail.com>
Co-authored-by: Korbinian Kottmann <43949391+Qottmann@users.noreply.github.com>
Co-authored-by: Ivana Kurečić <ivana@xanadu.ai>
Co-authored-by: Paul Finlay <50180049+doctorperceptron@users.noreply.github.com>
Co-authored-by: Jack Brown <jack.brown486@gmail.com>
Co-authored-by: bellekaplan <167111433+bellekaplan@users.noreply.github.com>
Co-authored-by: Utkarsh <utkarshazad98@gmail.com>
Co-authored-by: Pietropaolo Frisoni <pietropaolo.frisoni@xanadu.ai>
Co-authored-by: Guillermo Alonso-Linaje <65235481+KetpuntoG@users.noreply.github.com>
Co-authored-by: gmlej <gmlejarza@gmail.com>
Co-authored-by: Jorge J. Martínez de Lejarza <61199780+gmlejarza@users.noreply.github.com>
Co-authored-by: ixfoduap <40441298+ixfoduap@users.noreply.github.com>

Author: 14 people

Makefile

@@ -76,8 +76,8 @@ environment:
 			$$PYTHON_VENV_PATH/bin/python -m pip install --upgrade git+https://github.com/PennyLaneAI/pennylane-cirq.git#egg=pennylane-cirq;\
 			$$PYTHON_VENV_PATH/bin/python -m pip install --upgrade git+https://github.com/PennyLaneAI/pennylane-qiskit.git#egg=pennylane-qiskit;\
 			$$PYTHON_VENV_PATH/bin/python -m pip install --upgrade git+https://github.com/PennyLaneAI/pennylane-qulacs.git#egg=pennylane-qulacs;\
-			$$PYTHON_VENV_PATH/bin/python -m pip install --extra-index-url https://test.pypi.org/simple/ PennyLane-Lightning --pre --upgrade;\
 			$$PYTHON_VENV_PATH/bin/python -m pip install --extra-index-url https://test.pypi.org/simple/ PennyLane-Catalyst --pre --upgrade;\
+			$$PYTHON_VENV_PATH/bin/python -m pip install --extra-index-url https://test.pypi.org/simple/ PennyLane-Lightning --pre --upgrade;\
 			$$PYTHON_VENV_PATH/bin/python -m pip install --upgrade git+https://github.com/PennyLaneAI/pennylane.git#egg=pennylane;\
 		fi;\
 	fi

_static/demo_thumbnails/large_demo_thumbnails/thumbnail_large_how_to_use_quantum_arithmetic_operators.png

@@ -110,6 +110,9 @@
 
 # Raise PennyLane deprecation warnings as errors
 warnings.filterwarnings("error", category=PennyLaneDeprecationWarning)
+warnings.filterwarnings(
+    "ignore", message="Device will no longer be accessible", category=PennyLaneDeprecationWarning
+)
 
 # Add any paths that contain templates here, relative to this directory.
 templates_path = ["_templates"]

_static/demo_thumbnails/opengraph_demo_thumbnails/OGthumbnail_how_to_use_quantum_arithmetic_operators.png

@@ -55,7 +55,7 @@
 Let's have a go implementing the parameter-shift rule manually in PennyLane.
 """
 import pennylane as qml
-from jax import numpy as np
+from jax import numpy as jnp
 from matplotlib import pyplot as plt
 import jax
 
@@ -69,19 +69,28 @@
 # create a device to execute the circuit on
 dev = qml.device("default.qubit", wires=3)
 
+
+def CNOT_ring(wires):
+    """Apply CNOTs in a ring pattern"""
+    n_wires = len(wires)
+
+    for w in wires:
+        qml.CNOT([w % n_wires, (w + 1) % n_wires])
+
+
 @qml.qnode(dev, diff_method="parameter-shift")
 def circuit(params):
     qml.RX(params[0], wires=0)
     qml.RY(params[1], wires=1)
     qml.RZ(params[2], wires=2)
 
-    qml.broadcast(qml.CNOT, wires=[0, 1, 2], pattern="ring")
+    CNOT_ring(wires=[0, 1, 2])
 
     qml.RX(params[3], wires=0)
     qml.RY(params[4], wires=1)
     qml.RZ(params[5], wires=2)
 
-    qml.broadcast(qml.CNOT, wires=[0, 1, 2], pattern="ring")
+    CNOT_ring(wires=[0, 1, 2])
     return qml.expval(qml.PauliY(0) @ qml.PauliZ(2))
 
 
@@ -109,10 +118,10 @@ def circuit(params):
 
 def parameter_shift_term(qnode, params, i):
     shifted = params.copy()
-    shifted = shifted.at[i].add(np.pi/2)
+    shifted = shifted.at[i].add(jnp.pi/2)
     forward = qnode(shifted)  # forward evaluation
 
-    shifted = shifted.at[i].add(-np.pi)
+    shifted = shifted.at[i].add(-jnp.pi)
     backward = qnode(shifted) # backward evaluation
 
     return 0.5 * (forward - backward)
@@ -125,7 +134,7 @@ def parameter_shift_term(qnode, params, i):
 # to loop over the index ``i``:
 
 def parameter_shift(qnode, params):
-    gradients = np.zeros([len(params)])
+    gradients = jnp.zeros([len(params)])
 
     for i in range(len(params)):
         gradients = gradients.at[i].set(parameter_shift_term(qnode, params, i))
@@ -147,7 +156,7 @@ def parameter_shift(qnode, params):
 # Alternatively, we can directly compute quantum gradients of QNodes using
 # PennyLane's built in :mod:`qml.gradients <pennylane.gradients>` module:
 
-print(np.stack(qml.gradients.param_shift(circuit)(params)))
+print(jnp.stack(qml.gradients.param_shift(circuit)(params)))
 
 ##############################################################################
 # If you count the number of quantum evaluations, you will notice that we had to evaluate the circuit
@@ -372,10 +381,10 @@ def circuit(params):
     t = timeit.repeat("grad_qnode_backprop(params)", globals=globals(), number=num, repeat=reps)
     gradient_backprop.append([num_params, min(t) / num])
 
-gradient_shift = np.array(gradient_shift).T
-gradient_backprop = np.array(gradient_backprop).T
-forward_shift = np.array(forward_shift).T
-forward_backprop = np.array(forward_backprop).T
+gradient_shift = jnp.array(gradient_shift).T
+gradient_backprop = jnp.array(gradient_backprop).T
+forward_shift = jnp.array(forward_shift).T
+forward_backprop = jnp.array(forward_backprop).T
 
 ##############################################################################
 # We now import matplotlib, and plot the results.
@@ -419,8 +428,8 @@ def circuit(params):
 # perform a least squares regression to determine the linear best fit/gradient
 # for the normalized time vs. number of parameters
 x = gradient_shift[0]
-m_shift, c_shift = np.polyfit(*gradient_shift, deg=1)
-m_back, c_back = np.polyfit(*gradient_backprop, deg=1)
+m_shift, c_shift = jnp.polyfit(*gradient_shift, deg=1)
+m_back, c_back = jnp.polyfit(*gradient_backprop, deg=1)
 
 ax.plot(x, m_shift * x + c_shift, '--', label=f"{m_shift:.2f}p{c_shift:+.2f}")
 ax.plot(x, m_back * x + c_back, '--', label=f"{m_back:.2f}p{c_back:+.2f}")

_static/demo_thumbnails/regular_demo_thumbnails/thumbnail_how_to_use_quantum_arithmetic_operators.png

@@ -41,6 +41,10 @@
 import matplotlib.pyplot as plt
 import numpy as np
 
+# This filter will suppress deprecation warnings for viewability
+import warnings
+warnings.filterwarnings("ignore", "QubitDevice", qml.PennyLaneDeprecationWarning)
+
 
 def bell_pair():
     qml.Hadamard(0)

_static/demonstration_assets/how_to_use_quantum_arithmetic_operators/in_outplace.png

@@ -42,7 +42,7 @@
 Thus, we can improve the estimates of observables without breaking the differentiable workflow of our variational algorithm.
 We will briefly introduce these functionalities and afterwards go more in depth to explore what happens under the hood.
 
-We start by initializing a noisy device under the :class:`~.pennylane.DepolarizingChannel`:
+We start by initializing a noisy device using a noise model with :class:`~.pennylane.DepolarizingChannel` errors:
 """
 
 import pennylane as qml
@@ -54,13 +54,14 @@
 n_wires = 4
 np.random.seed(1234)
 
-# Describe noise
-noise_gate = qml.DepolarizingChannel
-noise_strength = 0.05
+# Describe noise model
+fcond = qml.noise.wires_in(range(n_wires))
+noise = qml.noise.partial_wires(qml.DepolarizingChannel, 0.05)
+noise_model = qml.NoiseModel({fcond: noise})
 
 # Load devices
 dev_ideal = qml.device("default.mixed", wires=n_wires)
-dev_noisy = qml.transforms.insert(dev_ideal, noise_gate, noise_strength, position="all")
+dev_noisy = qml.add_noise(dev_ideal, noise_model=noise_model)
 
 ##############################################################################
 # We are going to use the transverse field Ising model Hamiltonian :math:`H = - \sum_i X_i X_{i+1} + 0.5 \sum_i Z_i` as our observable:
@@ -85,8 +86,9 @@ def qfunc(w1, w2):
     qml.SimplifiedTwoDesign(w1, w2, wires=range(n_wires))
     return qml.expval(H)
 
-qnode_noisy = qml.QNode(qfunc, dev_noisy)
 qnode_ideal = qml.QNode(qfunc, dev_ideal)
+qnode_noisy = qml.QNode(qfunc, dev_noisy)
+qnode_noisy = qml.transforms.decompose(qnode_noisy, gate_set = ["RY", "CZ"])
 
 ##############################################################################
 # We can then simply transform the noisy QNode :math:`f^{⚡}` with :func:`~.pennylane.transforms.mitigate_with_zne` to generate :math:`\tilde{f}.`

conf.py

@@ -49,31 +49,35 @@
 Mitigating noise in a simple circuit
 ------------------------------------
 
-We first need a noisy device to execute our circuit on. Let's keep things simple for now by loading
-the :mod:`default.mixed <pennylane.devices.default_mixed>` simulator and artificially adding
-:class:`PhaseDamping <pennylane.PhaseDamping>` noise.
+We first need a noisy device to execute our circuit on. Let's keep things simple
+for now by loading the :mod:`default.mixed <pennylane.devices.default_mixed>` simulator
+and artificially adding :class:`PhaseDamping <pennylane.PhaseDamping>` noise using a
+:class:`NoiseModel <pennylane.NoiseModel>`.
 """
 
 import pennylane as qml
 
 n_wires = 4
 
-# Describe noise
-noise_gate = qml.PhaseDamping
-noise_strength = 0.1
+# Describe noise model
+fcond = qml.noise.wires_in(range(n_wires))
+noise = qml.noise.partial_wires(qml.PhaseDamping, 0.1)
+noise_model = qml.NoiseModel({fcond: noise})
 
 # Load devices
 dev_ideal = qml.device("default.mixed", wires=n_wires)
-dev_noisy = qml.transforms.insert(dev_ideal, noise_gate, noise_strength)
+dev_noisy = qml.add_noise(dev_ideal, noise_model=noise_model)
 
 ###############################################################################
-# In the above, we load a noise-free device ``dev_ideal`` and a noisy device ``dev_noisy``, which
-# is constructed from the :func:`qml.transforms.insert <pennylane.transforms.insert>` transform.
-# This transform works by intercepting each circuit executed on the device and adding the
-# :class:`PhaseDamping <pennylane.PhaseDamping>` noise channel directly after every gate in the
-# circuit. To get a better understanding of noise channels like
-# :class:`PhaseDamping <pennylane.PhaseDamping>`, check out the :doc:`tutorial_noisy_circuits`
-# tutorial.
+# In the above, we load a noise-free device ``dev_ideal`` and a noisy device ``dev_noisy``,
+# which is constructed from the :func:`qml.add_noise <pennylane.transforms.add_noise>`
+# transform. This transform works by intercepting each circuit executed on the device and
+# adding the noise to it based on the ``noise_model``. For example, in this case, it will
+# add :class:`PhaseDamping <pennylane.PhaseDamping>` noise channel after every gate in the
+# circuit acting on wires :math:`[0, 1, 2, 3]`. To get a better understanding of noise
+# channels like :class:`PhaseDamping <pennylane.PhaseDamping>` and using noise models,
+# check out the :doc:`tutorial_noisy_circuits` and :doc:`tutorial_how_to_use_noise_models`
+# tutorials, respectively.
 #
 # The next step is to define our circuit. Inspired by the mirror circuits concept introduced by
 # Proctor *et al.* [#proctor2020measuring]_ let's fix a circuit that applies a unitary :math:`U`
@@ -112,6 +116,7 @@ def circuit(w1, w2):
 
 ideal_qnode = qml.QNode(circuit, dev_ideal)
 noisy_qnode = qml.QNode(circuit, dev_noisy)
+noisy_qnode = qml.transforms.decompose(noisy_qnode, gate_set = ["RY", "CZ"])
 
 ##############################################################################
 # First, we'll visualize the circuit:
@@ -490,6 +495,7 @@ def qchem_circuit(phi):
 
     ideal_energy = qml.QNode(qchem_circuit, dev_ideal)
     noisy_energy = qml.QNode(qchem_circuit, dev_noisy)
+    noisy_energy = qml.transforms.decompose(noisy_energy, gate_set=["RX", "RY", "RZ", "CNOT"])
 
     ideal_energies.append(ideal_energy(phi))
     noisy_energies.append(noisy_energy(phi))
@@ -517,6 +523,7 @@ def qchem_circuit(phi):
         qml.DoubleExcitation(phi, wires=range(n_wires)),
     ]
     circuit = qml.tape.QuantumTape(ops)
+    [circuit], _ = qml.transforms.decompose(circuit, gate_set=["RX", "RY", "RZ", "CNOT"])
 
     # Define custom executor that expands Hamiltonian measurement
     # into a linear combination of tensor products of Pauli