Hybrid backends: qubits and bosons

Hi,

I hope that you are doing well.

I am aware that a similar question has been asked before here: Hybrid qubit-qumode gate . Since the question was asked some years ago, I am checking for potential updates.

I was curious whether it is possible to define quantum circuits in PennyLane that combine qubits and bosonic modes. For example, is it possible to simulate the famous Jaynes-Cummings interaction in Pennylane? If so, is the circuit differentiable, and can it be run on a GPU?

Thanks in advance for your help.

Cordially,

Taha

Hi @Taha , welcome to the Forum!

Unfortunately there’s no Hybrid qubit-qumode gate. However, you could potentially create a hybrid program by using two or more qnodes, each with a different device. You can see an example in our hybrid plugins demo, although I would recommend switching out the StrawberryFields device to PennyLane’s default.gaussian device.

I don’t know if this would be enough to simulate the Jaynes-Cummings interaction in PennyLane, but please let us know if you can make it work!

Almost everything in PennyLane is differentiable so I don’t think that should be a problem, but optimizations for GPU are only limited to certain devices. You can run the program on a GPU if you use the PyTorch interface for example, but it will not be fully optimized for that in the same way as certain PennyLane devices.

If you want to try this out I would recommend starting with a small example, maybe the one in the demo but adapted to the default.gaussian device.

I hope this helps!

Hi @CatalinaAlbornoz

Thank you for your response.

I think that common Pennylane libraries do not allow for entangling between a boson and a qubit. I have, however, found this library: GitHub - pnnl/hybridlane: A frontend library for hybrid CV-DV computation based on Pennylane , which can simulate hybrid boson-qubit systems.

Best,

Taha

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It’s great to see that you found a solution that works for you!

Thanks for sharing it here @Taha .