[RFC] Python frontend for photonic simulator

Required prerequisites

• Search the issue tracker to check if your feature has already been mentioned or rejected in other issues.

Describe the feature

• Add support to use the photonics simulator with photonics-cpu target from Python frontend of CUDA-Q

• Proposed API

  • Gates (same as those supported on C++ frontend):

    1. plus(q: qudit) -> None,
    2. phase_shift(q: qudit, phi: float) -> None,
    3. beam_splitter(q: qudit, r: qudit, theta: float) -> None,
    4. mz(q: qudit) -> int and mz(q: list[qudit]) -> list[int]

  • Handler is inferred from the target

  • Custom handler must provide API for defining a qudit of level = N, for example, qudit(3)

  • APIs

    • Synchronous sampling: cudaq.sample(*args, **kwargs)
    • State retrieval: cudaq.get_state(*args, **kwargs)

• Example

import cudaq

cudaq.set_target("photonics-cpu")


@cudaq.kernel
def photonicsKernel():    
    qutrits = [qudit(3) for i in range(2)]
    plus(qutrits[0])
    plus(qutrits[1])
    plus(qutrits[1])
    mz(qutrits)


counts = cudaq.sample(photonicsKernel)
print(counts)

state = cudaq.get_state(photonicsKernel)
print(state)