Extensible, Efficient Quantum Algorithm Design for Humans.


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Extensible, Efficient Quantum Algorithm Design for Humans.


Yao is an open source framework for

  • quantum algorithm design;
  • quantum software 2.0;
  • quantum computation education.

We are in an early-release beta. Expect some adventures and rough edges.


Yao is a julia language package. To install Yao, please open Julia's interactive session (known as REPL) and type ] in the REPL to use the package mode, then type this command:

pkg> add Yao

If you have problem to install the package, please file us an issue.

For CUDA support, see CuYao.jl.

Getting Started

Examples: understand Yao's code for quantum algorithms


  • STABLE — most recently tagged version of the documentation.
  • LATEST — in-development version of the documentation.


Algoritm Zoo

Some quantum algorithms are implemented with Yao in QuAlgorithmZoo.


Comparing with state of art quantum simulators, our library is inspired by quantum circuit optimization. Variational quantum optimization algorithms like quantum circuit Born machine (QCBM), quantum approximate optimization algorithm (QAOA), variational quantum eigensolver (VQE) and quantum circuit learning (QCL) et. al. are promising killer apps on a near term quantum computers. These algorithms require the flexibility to tune parameters and have well defined patterns such as "Arbitrary Rotation Block" and "CNOT Entangler".

In Yao, we call these patterns "blocks". If we regard every gate or gate pattern as a "block", then the framework can

  • be flexible to dispatch parameters,
  • cache matrices of blocks to speed up future runs,
  • allow hierarchical design of quantum algorithms

Thanks to Julia's duck type and multiple dispatch features, user can

  • easily extend the block system by overloading specific interfaces
  • quantum circuit blocks can be dispatched to some special method to improve the performance in specific case (e.g. customized repeat block of H gate).


Yao is a framework that is about to have the following features:

  • Extensibility
    • define new operations with a minimum number of methods in principle.
    • extend with new operations on different hardware should be easy, (e.g GPUs, near term quantum devices, FPGAs, etc.)
  • Efficiency
    • comparing with python, julia have no significant overhead on small scale circuit.
    • special optimized methods are dispatched to frequently used blocks.
    • double interfaces "apply!" and "cache server + mat" allow us to choose freely when to sacrifice memory for faster simulation and when to sacrifice the speed to simulate more qubits.
  • Easy to Use
    • As a white-box simulator, rather than using a black box, users will be aware of what their simulation are doing right through the interface.
    • Hierarchical APIs from low abstraction quantum operators to highly abstract circuit block objects.


Yao is a meta package based on several component packages in order to provide a highly modularized architecture, researchers and developers can extend the framework with different component packages for different purposes with minimal effort. The component packages includes:

  • YaoBase Interface definition and basic toolkits for registers.
  • YaoBlocks Standard basic quantum circuit simulator building blocks.
  • YaoArrayRegister Simulated Full Amplitude Quantum Register


To contribute to this project, please open an issue first to discuss with us in case we may not accept your PR.


This project is an effort of QuantumBFS, an open source organization for quantum science. All the contributors are listed in the contributors.

Papers Citing Yao

Variational Quantum Eigensolver with Fewer Qubits, Jin-Guo Liu, Yi-Hong Zhang, Yuan Wan, Lei Wang, https://arxiv.org/abs/1902.02663

Learning and inference on generative adversarial quantum circuits, Jinfeng Zeng, Yufeng Wu, Jin-Guo Liu, Lei Wang, and Jiangping Hu, Phys. Rev. A 99, 052306 – Published 6 May 2019


Yao is released under the Apache 2 license.

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