ITensor is a system for programming tensor network calculations with an interface modeled on tensor diagram notation, which allows users to focus on the connectivity of a tensor network without manually bookkeeping tensor indices. The ITensor interface rules out common programming errors and enables rapid prototyping of tensor network algorithms. After discussing the philosophy behind the ITensor approach, we show examples of each part of the interface including Index objects, the ITensor product operator, tensor factorizations, tensor storage types, algorithms for matrix product state (MPS) and matrix product operator (MPO) tensor networks, quantum number conserving block-sparse tensors, and the NDTensors library. We also review publications that have used ITensor for quantum many-body physics and for other areas where tensor networks are increasingly applied. To conclude we discuss promising features and optimizations to be added in the future.

中文翻译：

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用于张量网络计算的 ITensor 软件库

ITensor 是一个用于对张量网络计算进行编程的系统，其界面以张量图符号为模型，它允许用户专注于张量网络的连通性，而无需手动记录张​​量索引。ITensor 接口排除了常见的编程错误，并支持张量网络算法的快速原型设计。在讨论了 ITensor 方法背后的哲学之后，我们展示了接口每个部分的示例，包括索引对象、ITensor 乘积运算符、张量分解、张量存储类型、矩阵乘积状态 (MPS) 算法和矩阵乘积运算符 (MPO) 张量网络、量子数守恒块稀疏张量和 NDTensors 库。我们还回顾了将 ITensor 用于量子多体物理学和张量网络越来越多地应用的其他领域的出版物。最后，我们讨论了未来将添加的有前途的功能和优化。