Rename StatePrep to StatePrepBase and QubitStateVector to `Stat…

…ePrep` (#4450) * Support midcircuit stateprep * Added tests for code cobv * changelog * lint * fix typo * fix doc-string * address code review * Add support for defaultqubit2 * changelog * lint * lint * ci * ci * code review * renamed StatePrep --> InitialState * Support `StatePrep` mid-circuit for `DefaultQubit2` (#4444) * Add support for defaultqubit2 * changelog * lint * ci * code review * renamed QSV --> StatePrep * lint * Fixed test * lint * Fix doc * renamed -- * fixed bug and pylint * changelog fix + datasets fix * Apply suggestions from code review Co-authored-by: Christina Lee <christina@xanadu.ai> * fix tests * fix indent * Update pennylane/_qubit_device.py Co-authored-by: Christina Lee <christina@xanadu.ai> * lijnt --------- Co-authored-by: Christina Lee <christina@xanadu.ai> Co-authored-by: Mudit Pandey <mudit.pandey@xanadu.ai>
PennyLaneAI · Aug 17, 2023 · 7e0e5af · 7e0e5af
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diff --git a/doc/introduction/operations.rst b/doc/introduction/operations.rst
@@ -291,7 +291,7 @@ State preparation
  :nosignatures:
 
  ~pennylane.BasisState
- ~pennylane.QubitStateVector
+ ~pennylane.StatePrep
  ~pennylane.QubitDensityMatrix
 
 :html:`</div>`

diff --git a/doc/releases/changelog-dev.md b/doc/releases/changelog-dev.md
@@ -284,6 +284,10 @@ array([False, False])
 * The gradients module no longer needs shot information passed to it explicitly, as the shots are on the tapes.
  [(#4448)](https://github.com/PennyLaneAI/pennylane/pull/4448)
 
+* `StatePrep` is renamed to `StatePrepBase` and `QubitStateVector` is renamed to `StatePrep`.
+ `qml.operation.StatePrep` and `qml.QubitStateVector` will still be accessible for the time being.
+ [(#4450)](https://github.com/PennyLaneAI/pennylane/pull/4450)
+
 <h3>Deprecations 👋</h3>
 
 * ``qml.qchem.jordan_wigner`` is deprecated, use ``qml.jordan_wigner`` instead.

diff --git a/pennylane/_device.py b/pennylane/_device.py
@@ -40,7 +40,7 @@
  Variance,
 )
 
-from pennylane.operation import Observable, Operation, Tensor, Operator, StatePrep
+from pennylane.operation import Observable, Operation, Tensor, Operator, StatePrepBase
 from pennylane.ops import Hamiltonian, Sum
 from pennylane.tape import QuantumScript, QuantumTape, expand_tape_state_prep
 from pennylane.wires import WireError, Wires
@@ -665,9 +665,9 @@ def default_expand_fn(self, circuit, max_expansion=10):
  if max_expansion == 0:
  return circuit
 
- expand_state_prep = any(isinstance(op, StatePrep) for op in circuit.operations[1:])
+ expand_state_prep = any(isinstance(op, StatePrepBase) for op in circuit.operations[1:])
 
- if expand_state_prep: # expand mid-circuit StatePrep operations
+ if expand_state_prep: # expand mid-circuit StatePrepBase operations
  circuit = expand_tape_state_prep(circuit)
 
  comp_basis_sampled_multi_measure = (

diff --git a/pennylane/_qubit_device.py b/pennylane/_qubit_device.py
@@ -1991,7 +1991,7 @@ def adjoint_jacobian(
  )
  ops = op.decomposition()
  expanded_ops.extend(reversed(ops))
- elif op.name not in ("QubitStateVector", "BasisState", "Snapshot"):
+ elif op.name not in ("StatePrep", "QubitStateVector", "BasisState", "Snapshot"):
  expanded_ops.append(op)
 
  trainable_params = []

diff --git a/pennylane/data/attributes/operator/operator.py b/pennylane/data/attributes/operator/operator.py
@@ -126,6 +126,7 @@ def consumes_types(cls) -> FrozenSet[Type[Operator]]:
  # pennylane/ops/state_preparation.py
  qml.BasisState,
  qml.QubitStateVector,
+ qml.StatePrep,
  qml.QubitDensityMatrix,
  # pennylane/ops/qutrit/matrix_obs.py
  qml.QutritUnitary,

diff --git a/pennylane/devices/default_mixed.py b/pennylane/devices/default_mixed.py
@@ -31,7 +31,7 @@
  DeviceError,
  QubitDensityMatrix,
  QubitDevice,
- QubitStateVector,
+ StatePrep,
  Snapshot,
 )
 from pennylane import numpy as np
@@ -86,6 +86,7 @@ class DefaultMixed(QubitDevice):
  "Snapshot",
  "BasisState",
  "QubitStateVector",
+ "StatePrep",
  "QubitDensityMatrix",
  "QubitUnitary",
  "ControlledQubitUnitary",
@@ -604,7 +605,7 @@ def _apply_operation(self, operation):
  if operation.name == "Identity":
  return
 
- if isinstance(operation, QubitStateVector):
+ if isinstance(operation, StatePrep):
  self._apply_state_vector(operation.parameters[0], wires)
  return
 
@@ -755,7 +756,7 @@ def apply(self, operations, rotations=None, **kwargs):
 
  # apply the circuit operations
  for i, operation in enumerate(operations):
- if i > 0 and isinstance(operation, (QubitStateVector, BasisState)):
+ if i > 0 and isinstance(operation, (StatePrep, BasisState)):
  raise DeviceError(
  f"Operation {operation.name} cannot be used after other Operations have already been applied "
  f"on a {self.short_name} device."

diff --git a/pennylane/devices/default_qubit.py b/pennylane/devices/default_qubit.py
@@ -27,7 +27,7 @@
 from scipy.sparse import csr_matrix
 
 import pennylane as qml
-from pennylane import BasisState, DeviceError, QubitDevice, QubitStateVector, Snapshot
+from pennylane import BasisState, DeviceError, QubitDevice, StatePrep, Snapshot
 from pennylane.devices.qubit import measure
 from pennylane.operation import Operation
 from pennylane.ops import Sum
@@ -113,6 +113,7 @@ class DefaultQubit(QubitDevice):
  "Identity",
  "Snapshot",
  "BasisState",
+ "StatePrep",
  "QubitStateVector",
  "QubitUnitary",
  "ControlledQubitUnitary",
@@ -270,13 +271,13 @@ def apply(self, operations, rotations=None, **kwargs):
 
  # apply the circuit operations
  for i, operation in enumerate(operations):
- if i > 0 and isinstance(operation, (QubitStateVector, BasisState)):
+ if i > 0 and isinstance(operation, (StatePrep, BasisState)):
  raise DeviceError(
  f"Operation {operation.name} cannot be used after other Operations have already been applied "
  f"on a {self.short_name} device."
  )
 
- if isinstance(operation, QubitStateVector):
+ if isinstance(operation, StatePrep):
  self._apply_state_vector(operation.parameters[0], operation.wires)
  elif isinstance(operation, BasisState):
  self._apply_basis_state(operation.parameters[0], operation.wires)

diff --git a/pennylane/devices/null_qubit.py b/pennylane/devices/null_qubit.py
@@ -60,6 +60,7 @@ class NullQubit(QubitDevice):
  "Identity",
  "Snapshot",
  "BasisState",
+ "StatePrep",
  "QubitStateVector",
  "QubitUnitary",
  "ControlledQubitUnitary",

diff --git a/pennylane/devices/qubit/initialize_state.py b/pennylane/devices/qubit/initialize_state.py
@@ -21,15 +21,15 @@
 
 def create_initial_state(
  wires: Union[qml.wires.Wires, Iterable],
- prep_operation: qml.operation.StatePrep = None,
+ prep_operation: qml.operation.StatePrepBase = None,
  like: str = None,
 ):
  r"""
  Returns an initial state, defaulting to :math:`\ket{0}` if no state-prep operator is provided.
 
  Args:
  wires (Union[Wires, Iterable]): The wires to be present in the initial state
- prep_operation (Optional[StatePrep]): An operation to prepare the initial state
+ prep_operation (Optional[StatePrepBase]): An operation to prepare the initial state
  like (Optional[str]): The machine learning interface used to create the initial state.
  Defaults to None
 

diff --git a/pennylane/devices/qubit/preprocess.py b/pennylane/devices/qubit/preprocess.py
@@ -23,7 +23,7 @@
 
 import pennylane as qml
 
-from pennylane.operation import Tensor, StatePrep
+from pennylane.operation import Tensor, StatePrepBase
 from pennylane.measurements import (
  MidMeasureMP,
  StateMeasurement,
@@ -250,8 +250,8 @@ def expand_fn(circuit: qml.tape.QuantumScript) -> qml.tape.QuantumScript:
 
  if not all(_accepted_operator(op) for op in circuit.operations):
  try:
- # don't decompose initial operations if its StatePrep
- prep_op = [circuit[0]] if isinstance(circuit[0], StatePrep) else []
+ # don't decompose initial operations if its StatePrepBase
+ prep_op = [circuit[0]] if isinstance(circuit[0], StatePrepBase) else []
 
  new_ops = [
  final_op

diff --git a/pennylane/devices/qubit/simulate.py b/pennylane/devices/qubit/simulate.py
@@ -44,7 +44,7 @@ def get_final_state(circuit, debugger=None):
  circuit = qml.map_wires(circuit, wire_map)
 
  prep = None
- if len(circuit) > 0 and isinstance(circuit[0], qml.operation.StatePrep):
+ if len(circuit) > 0 and isinstance(circuit[0], qml.operation.StatePrepBase):
  prep = circuit[0]
 
  state = create_initial_state(circuit.wires, prep)

diff --git a/pennylane/devices/tests/test_gates.py b/pennylane/devices/tests/test_gates.py
@@ -65,6 +65,7 @@
  "CPhaseShift01": qml.CPhaseShift01(0, wires=[0, 1]),
  "CPhaseShift10": qml.CPhaseShift10(0, wires=[0, 1]),
  "QubitStateVector": qml.QubitStateVector(np.array([1.0, 0.0]), wires=[0]),
+ "StatePrep": qml.StatePrep(np.array([1.0, 0.0]), wires=[0]),
  "QubitDensityMatrix": qml.QubitDensityMatrix(np.array([[0.5, 0.0], [0, 0.5]]), wires=[0]),
  "QubitUnitary": qml.QubitUnitary(np.eye(2), wires=[0]),
  "SpecialUnitary": qml.SpecialUnitary(np.array([0.2, -0.1, 2.3]), wires=1),
@@ -391,8 +392,8 @@ def circuit():
  expected[np.ravel_multi_index(basis_state, [2] * n_wires)] = 1
  assert np.allclose(res, expected, atol=tol(dev.shots))
 
- def test_qubit_state_vector(self, device, init_state, tol, skip_if):
- """Test QubitStateVector initialisation."""
+ def test_state_prep(self, device, init_state, tol, skip_if):
+ """Test StatePrep initialisation."""
  n_wires = 1
  dev = device(n_wires)
  skip_if(dev, {"returns_probs": False})
@@ -401,7 +402,7 @@ def test_qubit_state_vector(self, device, init_state, tol, skip_if):
 
  @qml.qnode(dev)
  def circuit():
- qml.QubitStateVector(rnd_state, wires=range(n_wires))
+ qml.StatePrep(rnd_state, wires=range(n_wires))
  return qml.probs(range(n_wires))
 
  res = circuit()
@@ -420,7 +421,7 @@ def test_single_qubit_no_parameters(self, device, init_state, op, mat, tol, skip
 
  @qml.qnode(dev)
  def circuit():
- qml.QubitStateVector(rnd_state, wires=range(n_wires))
+ qml.StatePrep(rnd_state, wires=range(n_wires))
  op(wires=range(n_wires))
  return qml.probs(wires=range(n_wires))
 
@@ -441,7 +442,7 @@ def test_single_qubit_parameters(self, device, init_state, op, func, gamma, tol,
 
  @qml.qnode(dev)
  def circuit():
- qml.QubitStateVector(rnd_state, wires=range(n_wires))
+ qml.StatePrep(rnd_state, wires=range(n_wires))
  op(gamma, wires=range(n_wires))
  return qml.probs(wires=range(n_wires))
 
@@ -463,7 +464,7 @@ def test_rotation(self, device, init_state, tol, skip_if):
 
  @qml.qnode(dev)
  def circuit():
- qml.QubitStateVector(rnd_state, wires=range(n_wires))
+ qml.StatePrep(rnd_state, wires=range(n_wires))
  qml.Rot(a, b, c, wires=range(n_wires))
  return qml.probs(wires=range(n_wires))
 
@@ -485,7 +486,7 @@ def test_two_qubit_no_parameters(self, device, init_state, op, mat, tol, skip_if
 
  @qml.qnode(dev)
  def circuit():
- qml.QubitStateVector(rnd_state, wires=range(n_wires))
+ qml.StatePrep(rnd_state, wires=range(n_wires))
  op(wires=range(n_wires))
  return qml.probs(wires=range(n_wires))
 
@@ -506,7 +507,7 @@ def test_two_qubit_parameters(self, device, init_state, op, func, param, tol, sk
 
  @qml.qnode(dev)
  def circuit():
- qml.QubitStateVector(rnd_state, wires=range(n_wires))
+ qml.StatePrep(rnd_state, wires=range(n_wires))
  op(param, wires=range(n_wires))
  return qml.probs(wires=range(n_wires))
 
@@ -530,7 +531,7 @@ def test_qubit_unitary(self, device, init_state, mat, tol, skip_if):
 
  @qml.qnode(dev)
  def circuit():
- qml.QubitStateVector(rnd_state, wires=range(n_wires))
+ qml.StatePrep(rnd_state, wires=range(n_wires))
  qml.QubitUnitary(mat, wires=list(range(n_wires)))
  return qml.probs(wires=range(n_wires))
 
@@ -554,7 +555,7 @@ def test_special_unitary(self, device, init_state, theta_, tol, skip_if):
 
  @qml.qnode(dev)
  def circuit():
- qml.QubitStateVector(rnd_state, wires=range(n_wires))
+ qml.StatePrep(rnd_state, wires=range(n_wires))
  qml.SpecialUnitary(theta_, wires=list(range(n_wires)))
  return qml.probs(wires=range(n_wires))
 
@@ -579,7 +580,7 @@ def test_three_qubit_no_parameters(self, device, init_state, op, mat, tol, skip_
 
  @qml.qnode(dev)
  def circuit():
- qml.QubitStateVector(rnd_state, wires=range(n_wires))
+ qml.StatePrep(rnd_state, wires=range(n_wires))
  op(wires=[0, 1, 2])
  return qml.probs(wires=range(n_wires))
 

diff --git a/pennylane/devices/tests/test_gates_with_expval.py b/pennylane/devices/tests/test_gates_with_expval.py
@@ -83,7 +83,7 @@ def test_state_vector_3_qubit_subset(self, device, tol, par, wires, expected_out
 
  @qml.qnode(dev)
  def circuit():
- qml.QubitStateVector(par, wires=wires)
+ qml.StatePrep(par, wires=wires)
  return qml.expval(qml.PauliZ(0)), qml.expval(qml.PauliZ(1)), qml.expval(qml.PauliZ(2))
 
  assert np.allclose(circuit(), expected_output, atol=tol(dev.shots))
@@ -213,7 +213,7 @@ def test_supported_gate_two_wires_with_parameters(
 
  @qml.qnode(dev)
  def circuit():
- qml.QubitStateVector(np.array([1 / 2, 0, 0, sqrt(3) / 2]), wires=[0, 1])
+ qml.StatePrep(np.array([1 / 2, 0, 0, sqrt(3) / 2]), wires=[0, 1])
  op(*par, wires=[0, 1])
  return qml.expval(qml.PauliZ(0)), qml.expval(qml.PauliZ(1))
 
@@ -263,7 +263,7 @@ def test_supported_gate_two_wires_no_parameters(self, device, tol, name, expecte
 
  @qml.qnode(dev)
  def circuit():
- qml.QubitStateVector(np.array([1 / 2, 0, 0, sqrt(3) / 2]), wires=[0, 1])
+ qml.StatePrep(np.array([1 / 2, 0, 0, sqrt(3) / 2]), wires=[0, 1])
  op(wires=[0, 1])
  return qml.expval(qml.PauliZ(0)), qml.expval(qml.PauliZ(1))
 

diff --git a/pennylane/operation.py b/pennylane/operation.py
@@ -121,11 +121,11 @@
  ~CVOperation
  ~Channel
  ~Tensor
- ~StatePrep
+ ~StatePrepBase
 
 .. currentmodule:: pennylane.operation
 
-.. inheritance-diagram:: Operator Operation Observable Channel CV CVObservable CVOperation Tensor StatePrep
+.. inheritance-diagram:: Operator Operation Observable Channel CV CVObservable CVOperation Tensor StatePrepBase
  :parts: 1
 
 Errors
@@ -2827,7 +2827,7 @@ def heisenberg_obs(self, wire_order):
  return self.heisenberg_expand(U, wire_order)
 
 
-class StatePrep(Operation):
+class StatePrepBase(Operation):
  """An interface for state-prep operations."""
 
  grad_method = None
@@ -3011,3 +3011,10 @@ def active_new_opmath():
  True
  """
  return __use_new_opmath
+
+
+def __getattr__(name):
+ """To facilitate StatePrep rename"""
+ if name == "StatePrep":
+ return StatePrepBase
+ raise AttributeError(f"module 'pennylane.operation' has no attribute '{name}'")
diff --git a/pennylane/ops/functions/is_commuting.py b/pennylane/ops/functions/is_commuting.py
@@ -260,8 +260,9 @@ def check_commutation_two_non_simplified_rotations(operation1, operation2):
  "SProd",
 ]
 non_commuting_operations = [
- # State Prep
+ # StatePrepBase
  "QubitStateVector",
+ "StatePrep",
  "BasisState",
  # Templates
  "ArbitraryStatePreparation",

diff --git a/pennylane/ops/qubit/__init__.py b/pennylane/ops/qubit/__init__.py
@@ -90,6 +90,7 @@
  "IsingZZ",
  "IsingXY",
  "BasisState",
+ "StatePrep",
  "QubitStateVector",
  "QubitDensityMatrix",
  "QubitUnitary",

diff --git a/pennylane/ops/qubit/attributes.py b/pennylane/ops/qubit/attributes.py
@@ -237,6 +237,7 @@ def __contains__(self, obj):
  "OrbitalRotation",
  "FermionicSWAP",
  "QubitStateVector",
+ "StatePrep",
  "AmplitudeEmbedding",
  "AngleEmbedding",
  "IQPEmbedding",