Deprecations

Pending deprecations

• The get_operation tape method is updated to return the operation index as well, changing its signature.

  • The new signature is available by changing the arg return_op_index to True in v0.29

  • The old signature is replaced with the new one in v0.30

• The observables argument in QubitDevice.statistics is deprecated. Please use circuit instead. Using a list of observables in QubitDevice.statistics is deprecated. Please use a QuantumTape instead.

  • Still accessible in v0.28, v0.29

  • Will be removed in v0.30

• The seed_recipes argument in qml.classical_shadow and qml.shadow_expval is deprecated. A new argument seed has been added, which defaults to None and can contain an integer with the wanted seed.

  • Still accessible in v0.28, v0.29

  • Will be removed in v0.30

• The grouping module is deprecated. The functionality has been moved and reorganized in the new pauli module under pauli/utils.py or pauli/grouping/.

  • Still accessible in v0.27, v0.28, v0.29

  • Will be removed in v0.30

  The functions from grouping/pauli.py, grouping/transformations.py and grouping/utils.py have been moved to pauli/utils.py. The remaining functions have been consolidated in the pauli/grouping/ directory.

• qml.ExpvalCost has been deprecated, and usage will now raise a warning.

  • Deprecated in v0.24

  • Will be removed in v0.30

  Instead, it is recommended to simply pass Hamiltonians to the qml.expval function inside QNodes:

  @qml.qnode(dev)
  def ansatz(params):
      some_qfunc(params)
      return qml.expval(Hamiltonian)
  

• The collections module has been deprecated.

  • Deprecated in v0.29

  • Will be removed in v0.31

• qml.op_sum` is deprecated. Users should use qml.sum instead.

  • Deprecated in v0.29.

  • Will be removed in v0.31.

• A warning has been added in Evolution redirecting users to qml.evolve. This was added because we want to change the behaviour of Evolution, adding a -1 to the given parameter.

  • Deprecated in v0.29.

  • Will be removed in v0.30.

• The qml.utils.sparse_hamiltonian function is deprecated. ~.Hamiltonian.sparse_matrix should be used instead.

  • Deprecated in v0.29

  • Removed in v0.31

Completed deprecation cycles

• qml.VQECost is removed.

  • Deprecated in 0.13

  • Removed in 0.29

• In-place inversion — op.inv() and op.inverse=value — is deprecated. Please use qml.adjoint or qml.pow instead.

  • Still accessible in v0.27 and v0.28

  • Removed in v0.29

  Don’t use:

  >>> v1 = qml.PauliX(0).inv()
  >>> v2 = qml.PauliX(0)
  >>> v2.inverse = True
  

  Instead, use:

  >>> qml.adjoint(qml.PauliX(0))
  Adjoint(PauliX(wires=[0]))
  >>> qml.pow(qml.PauliX(0), -1)
  PauliX(wires=[0])**-1
  >>> qml.pow(qml.PauliX(0), -1, lazy=False)
  PauliX(wires=[0])
  >>> qml.PauliX(0) ** -1
  PauliX(wires=[0])**-1
  

• The qml.utils.decompose_hamiltonian() method is removed. Please use qml.pauli_decompose().

  • Still accessible in v0.27

  • Removed in v0.28

• qml.tape.get_active_tape is deprecated. Please use qml.QueuingManager.active_context() instead.

  • Deprecated in v0.27

  • Removed in v0.28

• qml.transforms.qcut.remap_tape_wires is deprecated. Please use qml.map_wires instead.

  • Deprecated in v0.27

  • Removed in v0.28

• QuantumTape.inv() is deprecated. Please use QuantumTape.adjoint() instead. This method returns a new tape instead of modifying itself in-place.

  • Deprecated in v0.27

  • Removed in v0.28

• qml.tape.stop_recording and QuantumTape.stop_recording are moved to qml.QueuingManager.stop_recording

  • Deprecated in v0.27

  • Removed in v0.28

• QueuingContext is renamed QueuingManager.

  • Deprecated name QueuingContext in v0.27

  • Removed in v0.28

• QueuingManager.safe_update_info and AnnotateQueue.safe_update_info are removed.

  • Deprecated in v0.27

  • Removed in v0.28

• ObservableReturnTypes Sample, Variance, Expectation, Probability, State, and MidMeasure are moved to measurements from operation.

  • Deprecated in v0.23

  • Removed in v0.27

• The qml.utils.expand function is deprecated. qml.math.expand_matrix should be used instead.

  • Deprecated in v0.24

  • Removed in v0.27

• The qml.Operation.get_parameter_shift method is removed. Use the methods of the gradients module for general parameter-shift rules instead.

  • Deprecated in v0.22

  • Removed in v0.28

• qml.transforms.measurement_grouping has been removed. Please use qml.transforms.hamiltonian_expand instead.

  • Deprecated in v0.28

  • Removed in v0.29

• qml.transforms.make_tape was previously deprecated, but there is no longer a plan to remove it. It no longer raises a warning, and the functionality is unchanged.

  • Deprecated in v0.28

  • Un-deprecated in v0.29

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