`from_state` error with `kernel.qalloc()`

[anthony-santana]

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Describe the bug

There is a runtime error when passing a single qubit that's been allocated with kernel.qalloc() to cudaq.from_state. The bug goes away when allocating a single qubit in a qvec kernel.qalloc(1).

Steps to reproduce the bug

import cudaq
import numpy as np

state = np.array([0,1])

kernel = cudaq.make_kernel()
qubit = kernel.qalloc()
# ok with:
# qubit = kernel.qalloc(1)

cudaq.from_state(kernel, qubit, state)
> RuntimeError: [from_state] cannot infer size of input quantum register, please specify the number of qubits via the from_state() final argument.

Expected behavior

Expect the from_state function to accept a single qubit that's not necessarily nested in a qvec. Or, we should pack the qubit in a temporary qvec behind the scenes.

Is this a regression? If it is, put the last known working version (or commit) here.

Not a regression

Environment

• CUDA Quantum version:
• Python version:
• C++ compiler:
• Operating system:

Suggestions

No response

[bettinaheim]

Needs to be confirmed if this is still an issue with the new state handling.