hexi-uestc/quimb

A python library for quantum information and many-body calculations including tensor networks -

---

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 many operations using numba and numexpr
• 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

The full documentation can be found at: http://quimb.readthedocs.io/en/latest/. Contributions of any sort are very welcome - please see the contributing guide.