I am trying to build an architecture that contains a feedback loop of a wire (with the strawberryfields.fock plugin). Every iteration, an input gets combined with a feedback state, after which it gets fed into a reservoir. Also every iteration, part of the reservoir output gets measured and part of the reservoir output gets feedbacked.
To combine the input state with the feedback state, I need some kind of combiner. For example (with 3 wires): if
psi_in = [0,1,0] and
psi_fb = 1/sqrt(2) [1,0,0] + 1/sqrt(2) [0,1,0], I want the result
psi_combined = 1/sqrt(2) [1,1,0] + 1/sqrt(2) [0,2,0].
In practice, I would do this with a
2x1 multimode interferometer (MMI). Is there some way to achieve this in PennyLane?
In StrawberryFields I thought about coupling the correct wires and using post-selection, but I can’t seem to use post-selection in PennyLane. Is that correct?
Kind regards and thanks in advance,