[BUG] Non-parametric operations require an updated `adjoint` method

[antalszava]

Expected behavior

Non-parametric operations have an adjoint method definition such as:

def adjoint(self):
    return SomeOperation(wires=self.wires).inv()

This definition always returns the inverse of the original operation. However, it doesn't consider the case when the original operation was inverted already.

E.g.,

qml.SX(wires=0).adjoint().adjoint()

returns

SX.inv(wires=[0])

Actual behavior

Would expect to have

SX(wires=[0])

returned.

Additional information

This type of change is upcoming in https://github.com/PennyLaneAI/pennylane/pull/1955. The things todo include implementing the same changes for other similar cases.

Source code

No response

Tracebacks

No response

System information

Name: PennyLane
Version: 0.20.0.dev0
Summary: PennyLane is a Python quantum machine learning library by Xanadu Inc.
Home-page: https://github.com/XanaduAI/pennylane
Author: 
Author-email: 
License: Apache License 2.0
Location: /home/antal/xanadu/pennylane
Requires: numpy, scipy, networkx, autograd, toml, appdirs, semantic_version, autoray, cachetools, pennylane-lightning
Required-by: PennyLane-Cirq, PennyLane-Orquestra, PennyLane-SF, pennylane-qulacs, PennyLane-IonQ, amazon-braket-pennylane-plugin, PennyLane-Honeywell, PennyLane-qiskit, PennyLane-AQT, PennyLane-Qchem, PennyLane-PQ, PennyLane-Forest, PennyLane-Lightning, PennyLane-qsharp
Platform info:           Linux-5.11.0-40-generic-x86_64-with-glibc2.10
Python version:          3.8.5
Numpy version:           1.21.4
Scipy version:           1.7.3
Installed devices:
- cirq.mixedsimulator (PennyLane-Cirq-0.17.1)
- cirq.pasqal (PennyLane-Cirq-0.17.1)
- cirq.qsim (PennyLane-Cirq-0.17.1)
- cirq.qsimh (PennyLane-Cirq-0.17.1)
- cirq.simulator (PennyLane-Cirq-0.17.1)
- orquestra.forest (PennyLane-Orquestra-0.15.0)
- orquestra.ibmq (PennyLane-Orquestra-0.15.0)
- orquestra.qiskit (PennyLane-Orquestra-0.15.0)
- orquestra.qulacs (PennyLane-Orquestra-0.15.0)
- strawberryfields.fock (PennyLane-SF-0.16.0.dev0)
- strawberryfields.gaussian (PennyLane-SF-0.16.0.dev0)
- strawberryfields.gbs (PennyLane-SF-0.16.0.dev0)
- strawberryfields.remote (PennyLane-SF-0.16.0.dev0)
- strawberryfields.tf (PennyLane-SF-0.16.0.dev0)
- qulacs.simulator (pennylane-qulacs-0.17.0.dev0)
- ionq.qpu (PennyLane-IonQ-0.17.0.dev0)
- ionq.simulator (PennyLane-IonQ-0.17.0.dev0)
- braket.aws.qubit (amazon-braket-pennylane-plugin-1.4.1.dev0)
- braket.local.qubit (amazon-braket-pennylane-plugin-1.4.1.dev0)
- honeywell.hqs (PennyLane-Honeywell-0.16.0.dev0)
- qiskit.aer (PennyLane-qiskit-0.18.0.dev0)
- qiskit.basicaer (PennyLane-qiskit-0.18.0.dev0)
- qiskit.ibmq (PennyLane-qiskit-0.18.0.dev0)
- aqt.noisy_sim (PennyLane-AQT-0.18.0)
- aqt.sim (PennyLane-AQT-0.18.0)
- projectq.classical (PennyLane-PQ-0.18.0.dev0)
- projectq.ibm (PennyLane-PQ-0.18.0.dev0)
- projectq.simulator (PennyLane-PQ-0.18.0.dev0)
- forest.numpy_wavefunction (PennyLane-Forest-0.18.0.dev0)
- forest.qvm (PennyLane-Forest-0.18.0.dev0)
- forest.wavefunction (PennyLane-Forest-0.18.0.dev0)
- lightning.qubit (PennyLane-Lightning-0.19.0.dev0)
- microsoft.QuantumSimulator (PennyLane-qsharp-0.19.0)
- default.gaussian (PennyLane-0.20.0.dev0)
- default.mixed (PennyLane-0.20.0.dev0)
- default.qubit (PennyLane-0.20.0.dev0)
- default.qubit.autograd (PennyLane-0.20.0.dev0)
- default.qubit.jax (PennyLane-0.20.0.dev0)
- default.qubit.tf (PennyLane-0.20.0.dev0)
- default.qubit.torch (PennyLane-0.20.0.dev0)
- default.tensor (PennyLane-0.20.0.dev0)
- default.tensor.tf (PennyLane-0.20.0.dev0)

• [X] I have searched exisisting GitHub issues to make sure the issue does not already exist.

[dwierichs]

@Jaybsoni This is solved, right?

[dwierichs]

@albi3ro Maybe you know more regarding this? As inv has been removed, I don't think this issue exists anymore.

[albi3ro]

Not a problem anymore. Closing the issue.