ITensor

ITensor has a paper! We lay out the philosophy behind ITensor and give lots of examples of the key parts of the interface (mostly in Julia). We also discuss some advanced features, NDTensors.jl, and some future plans. arxiv.org/abs/2007.14822

Example model 1D system showing a beyond-group symmetry studied with ITensor DMRG. "Non-invertible symmetry-protected topological order in a group-based cluster state" Christopher Fechisin, Nathanan Tantivasadakarn, Victor V. Albert. arxiv.org/abs/2312.09272

@aavishkar_patel Regarding alternatives to SVD, in some settings such as TEBD, QR can be used and is fundamentally cheaper and much more highly optimized for GPU: journals.aps.org/prb/abstract/1…

@aavishkar_patel Regarding bond dimension, GPU memory can be a serious limitation. We are looking into features like unified memory to help. Also moving parts of tensors between CPU and GPU or across multiple GPU's.

Our new ITensor GPU backend system is now live in the latest Julia version, building on hard work by Karl Pierce and Matt Fishman, using the elegant new package extension system. See Matt's post about the initial release here: itensor.discourse.group/t/ann-initial-…

Exciting update on what’s new in Julia. Very informative thread:

Roadmap for @ITensorLib at #juliacon, more details coming later in the mini! Get ready for tensor networks to solve everything 🤓.

@ITensorLib is BACK at #juliacon. Matt Fishman from @FlatironCCQ presenting exciting updates to my “decent” gpu backend, among others.

Beautiful agreement between numerics (DMRG based on ITensor) and Ginzburg-Landau theory calculations of coexistence of CDW and superconductivity in t-t'-U Hubbard model. arxiv.org/abs/2307.11820

From scratch implementation of DMRG using Julia version of ITensor by one of our users - check it out:

"Quantics tensor trains" (amplitude encoded functions represented as MPS) to represent Green's functions. Like using a tiny quantum computer to represent correlation functions of quantum systems (implemented with ITensor) journals.aps.org/prx/abstract/1…

Enhanced estimation of quantum state properties, tested using ITensor and PastaQ arxiv.org/abs/2304.12292

Why do some parts of ITensors.jl have type instabilities and use dynamic dispatch, and does this hurt performance? A good answer by Matt Fishman to this question: itensor.discourse.group/t/dynamic-disp…

Our DMRG study of the quantum critical point in 1D water is published @PhysRevLett. This work wouldn't be possible without the incredible @ITensorLib software. Also, don't miss the fantastic Viewpoint by Marivi Fernández-Serra @Perimeter @UWaterloo journals.aps.org/prl/abstract/1…

Compression of Green and vertex functions in real and momentum space as MPS and MPO tensor networks, for solving Dyson equation and other quantum applications (partially implemented with ITensors.jl):

@onur_danaci @drpeterrohde @RichCompNeuro @JuliaLanguage ITensor is written 100% in Julia, so doesn't call any C++ or Fortran (except BLAS which every language calls, including C++). Packages like Zygote and Flux are also all Julia.

@drpeterrohde @RichCompNeuro @JuliaLanguage Do computational packages on Julia like zygote, iTensor, flux etc run on Julia? Or are they just wrappers on low level languages (c++, fortran, etc) as in Python?

I think I just successfully translated some messy C++ code into clean Python code in an afternoon! The problem: I'm not 100% sure if it's working since the code is running about 10x slower in Python🤦‍♂️ Is this just the expected tradeoff for the ease/readability of Python?

@hakusai_47 If you have any questions about using ITensor, feel free to ask on our discussion board here: itensor.discourse.group

We also have a TDVP package that’s almost done - you can already use it now github.com/ITensor/ITenso…

To learn how to set up your own time-evolution code, see our tutorial here: itensor.github.io/ITensors.jl/st…

ITensor used to benchmark a state-of-art quantum simulator (Quantinuum trapped ion system used to simulate the quantum dynamics of a Floquet contact process) arxiv.org/abs/2209.12889