Welcome to quimb’s documentation!

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quimb is an easy but fast python library for quantum information and many-body calculations, including with tensor networks. The code is hosted on github, do please submit any issues or pull requests there. It is also thoroughly unit-tested and the tests might be the best place to look for detailed documentation.

The core quimb module:

  • Uses straight numpy and scipy.sparse matrices as quantum objects

  • Accelerates and parallelizes many operations using numba.

  • Makes it easy to construct operators in large tensor spaces (e.g. 2D lattices)

  • Uses efficient methods to compute various quantities including entanglement measures

  • Has many built-in states and operators, including those based on fast, parallel random number generation

  • Can perform evolutions with several methods, computing quantities on the fly

  • Has an optional slepc4py interface for easy distributed (MPI) linear algebra. This can massively increase the performance when seeking, for example, mid-spectrum eigenstates

The tensor network submodule quimb.tensor:

  • Uses a geometry free representation of tensor networks

  • Uses opt_einsum to find efficient contraction orders for hundreds or thousands of tensors

  • Can perform those contractions on various backends, including with a GPU

  • Can plot any network, color-coded, with bond size represented

  • Can treat any network as a scipy LinearOperator, allowing many decompositions

  • Can perform DMRG1, DMRG2 and DMRGX, in matrix product state language

  • Has tools to efficiently address periodic problems (transfer matrix compression and pseudo-orthogonalization)

  • Can perform MPS time evolutions with TEBD

  • Can optimize any tensor network with tensorflow or pytorch

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Citing

quimb is published in the Journal of Open Source Software here - if it’s ever useful in research please consider citing it!

@article{gray2018quimb,
  title={quimb: a python library for quantum information and many-body calculations},
  author={Gray, Johnnie},
  journal={Journal of Open Source Software},
  year = {2018},
  volume={3}, number={29}, pages={819},
  doi={10.21105/joss.00819},
}

Indices and tables

The following sections contain the complete listing of functions, classes and modules in quimb.