Matt Fishman

I guess that is a different issue particular to outer products. A workaround for that could be to add dummy (dimension-1) indices shared between tensors `B` and `C`.

Yeah, ideally we would fix that limitation, of course.

In the above, the data of tensor `A` is not allocated yet. Looks like it works if you initialize it with: ```julia A = ITensor(0.0, indices) ``` Though the original...

It is the same convention as Julia's `LinearAlgebra.mul!` function: https://docs.julialang.org/en/v1/stdlib/LinearAlgebra/#Low-level-matrix-operations.

Makes sense. We wouldn't want to do it in a way that users have to implement it for every `state` definition but we could do it as a post-processing.

That's an impressive speedup! I was trying to think if we can do this same kind of optimization automatically in our `inner` `rrule` but I don't really see how besides...

That sounds really strange. The compat entries of PastaQ.jl have barely changed between those versions: https://github.com/GTorlai/PastaQ.jl/blob/v0.0.20/Project.toml https://github.com/GTorlai/PastaQ.jl/blob/v0.0.24/Project.toml so I don't see why you would be seeing differences between those versions,...

Alright, so as I expected this is caused by a regression in Zygote. I tried running your code but pinning Zygote to an older version (Zygote v0.6.43, while the latest...

Alright, some more information. It looks like Zygote versions v0.6.44 and below work, and v0.6.45 and above fail at this same line of code in `insertnoise`. In the release notes...

Thanks! It would be nice to try to make as minimal of a code example as possible to reproduce the bug so then we can report it to Zygote. For...