[BUG] PhaseAdder not correct

[kevzos]

Expected behavior

import pennylane as qml
x = 6
k = 7
mod = 4

x_wires =[0,1,2,3]
work_wire=[5]

dev = qml.device("default.qubit", shots=1)
@qml.qnode(dev)
def circuit():
qml.BasisEmbedding(x, wires=x_wires)
qml.QFT(wires=x_wires)
qml.PhaseAdder(k, x_wires, mod, work_wire)
qml.adjoint(qml.QFT)(wires=x_wires)
return qml.sample(wires=x_wires)
print(circuit())
#[0,0,0,1]

Actual behavior

#got [0 1 0 1]
#(6+7)mod 4 expect 1 ?

Additional information

No response

Source code

No response

Tracebacks

No response

System information

Name: PennyLane
Version: 0.38.0
Summary: PennyLane is a cross-platform Python library for quantum computing, quantum machine learning, and quantum chemistry. Train a quantum computer the same way as a neural network.
Home-page: https://github.com/PennyLaneAI/pennylane
Author: 
Author-email: 
License: Apache License 2.0
Location: /root/anaconda3/envs/py310/lib/python3.10/site-packages
Requires: appdirs, autograd, autoray, cachetools, networkx, numpy, packaging, pennylane-lightning, requests, rustworkx, scipy, toml, typing-extensions
Required-by: PennyLane_Lightning

Platform info:           Linux-3.10.0-1160.90.1.el7.x86_64-x86_64-with-glibc2.17
Python version:          3.10.0
Numpy version:           1.23.5
Scipy version:           1.10.0
Installed devices:
- default.clifford (PennyLane-0.38.0)
- default.gaussian (PennyLane-0.38.0)
- default.mixed (PennyLane-0.38.0)
- default.qubit (PennyLane-0.38.0)
- default.qubit.autograd (PennyLane-0.38.0)
- default.qubit.jax (PennyLane-0.38.0)
- default.qubit.legacy (PennyLane-0.38.0)
- default.qubit.tf (PennyLane-0.38.0)
- default.qubit.torch (PennyLane-0.38.0)
- default.qutrit (PennyLane-0.38.0)
- default.qutrit.mixed (PennyLane-0.38.0)
- default.tensor (PennyLane-0.38.0)
- null.qubit (PennyLane-0.38.0)
- lightning.qubit (PennyLane_Lightning-0.38.0)

Existing GitHub issues

• I have searched existing GitHub issues to make sure the issue does not already exist.

[KetpuntoG]

Hi @kevzos , thanks for opening the report! :)
Note that in the documentation there is a note saying that to work the operator you must guarantee that x < mod. That must be the issue in this code

[justinpickering]

That's correct @KetpuntoG - could we raise a warning when x > mod? cc @josh146 @isaacdevlugt

[KetpuntoG]

Unfortunately that is not possible, the template has not information about |x> @justinpickering

[justinpickering]

Thanks for confirming, @KetpuntoG. We can close this ticket as no further action is required.
Thank you @kevzos for reporting this!

[kevzos]

@justinpickering Thanks for your answers.