Qsyn: A Developer-Friendly Quantum Circuit Synthesis Framework for NISQ Era and Beyond

Overview

Qsyn is a developer-friendly C++-based Quantum Circuit Compilation framework to aid further development in this field. The main contributions of Qsyn are:

• Providing a unified and user-friendly developing environment so researchers and developers can efficiently prototype, implement, and thoroughly evaluate their QCS algorithms with standardized tools, language, and data structures.
• Assisting the developers with a robust and intuitive interface that can access low-level data directly to provide developers with unique insights into the behavior of their algorithms during runtime.
• Inforcing robust quality-assurance practices, such as regression tests, continuous integration-and-continuous delivery (CI/CD) flows, linting, etc. These methodologies ensure that we provide reliable and efficient functionalities and that new features adhere to the same quality we strive for.

Some of the future work for Qsyn includes:

• Improving high-level synthesis: A well-designed high-level synthesis algorithm can yield efficient high-level circuits and adapt to the qubit resource constraint, simplifying the subsequent synthesis steps.
• More flexible gate-level synthesis: We aim to optimize multiple metrics simultaneously and characterize the trade-off between them. Device-aware synthesis strategies are also promising for further compacting the resulting circuits.
• Beyond NISQ devices: Fault-tolerant quantum architectures require decomposing the Clifford+T gate set and introducing new Clifford gate models. Distributed devices are also a common theme for realizing quantum advantage, necessitating algorithms targeting specifically for these devices.

Getting Started

System Requirements

qsyn requires c++-20 to build. We support compilation with (1) g++-11 or above or (2) clang++-16 or above. We regularly perform build tests for the two compilers.

Installation

Clone the repository to your local machine by running

git clone https://github.com/DVLab-NTU/qsyn.git
cd qsyn

Then, follow the instructions below to install the dependencies and build qsyn.

Alternatively, you can try out qsyn in a containerized environment by running

docker run -it --rm dvlab/qsyn:latest

if you have Docker installed on your machine.

Optional Dependencies for Visualization

Visualization functionalities of qsyn depend at runtime on the following dependencies. Please refer to the linked pages for installation instructions of these dependencies:

• qiskit, qiskit[visualization] for drawing quantum circuits
  • Please refer to this page
• texlive for drawing ZX-diagrams.
  • For Ubuntu:

    sudo apt-get install texlive-latex-base texlive-latex-extra

  • Other Platforms: please refer to this page

Compilation

To build qsyn, follow the instructions below:

For Linux Users

You'll probably need to install OpenBLAS and LAPACK libraries. For Ubuntu, you can install them by running

sudo apt install libopenblas-dev
sudo apt install liblapack-dev

If you are tech-savvy enough to be using a different Linux distribution, we're confident that you can figure out how to install these libraries 😉

Then, run the following commands to build qsyn:

make -j8

which triggers our suggested CMake build process. Alternatively, use make build-g++ or make build-clang++ to manually specify the compiler.

For MacOS Users

Since Qsyn uses some C++20 features that are not yet supported by Apple Clang, you'll need to install another compiler yourself. We recommend installing the llvm toolchain with the brew package manager.

brew install llvm

After installation, brew will guide you to configure your environment to use LLVM clang++ and its associated libraries.

You would probably want to install OpenBLAS by running

brew install openblas

Finally, run the following commands to build qsyn:

make -j8

which triggers our suggested CMake build process. Alternatively, use make build-g++ or make build-clang++ to manually specify the compiler.

Docker Builds

You can also build qsyn in a containerized environment by running

make build-docker

And run that executable by running

make run-docker

Of course, this requires you to have Docker installed on your machine.

Run

• After successful compilation, run ./qsyn and enter Qsyn's command-line interface:

   ./qsyn
   qsyn v0.7.0 - Copyright © 2022-2024, DVLab NTUEE.
   Licensed under Apache 2.0 License. Release build.
   qsyn>

• To see what commands are available, type help in the command-line interface.

  qsyn> help

• To see the help message of a specific command, type <command> -h or <command> --help.

  qsyn> qcir read -h

• You can also let qsyn to execute a sequence of commands by passing a script to qsyn:

  ./qsyn -v examples/synth.dof
  qsyn v0.7.0 - Copyright © 2022-2024, DVLab NTUEE.
  Licensed under Apache 2.0 License. Release build.
  qsyn> qcir read benchmark/SABRE/large/adr4_197.qasm
  # further executing commands...

  Some example scripts are provided under examples/. You can also write your own scripts to automate your workflow.

• qsyn also supports reading commands from scripts. For example, we also provided a ZX-calculus-based optimization flow by executing the following script in the project folder examples/zxopt.qsyn:

  //!ARGS INPUT
  qcir read ${INPUT}
  echo "--- pre-optimization ---"
  qcir print --stat
  // to zx -> full reduction -> extract qcir
  qc2zx; zx optimize --full; zx2qc
  // post-resyn optimization
  qcir optimize
  echo "--- post-optimization ---"
  qcir print --stat

  To run the commands in the above file, supply the script’s file path and arguments after ./qsyn :

  ./qsyn examples/zxopt.qsyn benchmark/SABRE/large/adr4_197.qasm

  This runs the ZX-calculus-based synthesis on the circuit in benchmark/SABRE/large/adr4_197.qasm.

• If you're using qsyn for the first time, a config file will be created under ~/.config/qsynrc and can be used to store your aliases, variables, etc. If you lost this file, you can use the command create-qsynrc to recreate it.

• For more options, please refer to the help message of qsyn by running

  ./qsyn -h

Testing

We have provided some test scripts as integrated tests as well as demonstration of use. These scripts are Located under tests/<section>/<subsection>/dof/.

• To run a test script and compare the result to the reference, type

  ./scripts/RUN_TESTS <path/to/test> -d

• To update the reference to a test script, type

  ./scripts/RUN_TESTS <path/to/test> -u

• You may also run all test scripts by running

  make test

• To run test in a containerized environment, run

  make test-docker

  Notice that if you use a different BLAS or LAPACK implementation to build qsyn, be expect that some of the test scripts may produce different results.

Functionalities

Software architecture

The core interaction with qsyn is facilitated through its command-line interface (CLI), which processes user input, handles command execution, and manages error reporting. Developers can add additional commands and integrate into the CLI. New strategy can be added without compromising to existing data structure, as all modifications are funneled through well-defined public interfaces.

qsyn supports real time storage of multiple quantum circuits and intermediate representations by the <dt> checkout command. Users can take snapshots at any time in the synthesis process and switch to an arbitrary version of stored data.

This architecture is central to qsyn’s flexibility and extensibility. It segregates responsibilities and simplifies command implementations while enhancing its capability as a research tool in quantum circuit synthesis.

High-level Synthesis

qsyn can process various specifications for quantum circuits by supporting syntheses from Boolean oracles and unitary matrices.

Command	Description
qcir oracle	ROS Boolean oracle synthesis flow
convert ts qc	Gray-code unitary matrix synthesis

Gate-level Synthesis

qsyn also adapt to different optimization targets by providing different routes to synthesize low-level quantum circuits.

Via ZX-calculus

Command	Description
qzq	ZX-calculus-based synth routine
convert qc zx	convert quantum circuit to ZX-diagram
zx opt	fully reduce ZX diagram
convert zx qc	convert ZX-diagram to quantum circuit
qc opt	basic optimization passes

Via Tableau

Command	Description
qtablq	tableau-based synth routine
convert qc tabl	convert quantum circuit to tableau
tabl opt full	iteratively apply the following three
tabl opt tmerge	phase-merging optimization
tabl opt hopt	internal H-gate optimization
tabl opt ph todd	TODD optimization
convert tabl qc	convert tableau to quantum circuit

Device Mapping

qsyn can target a wide variety of quantum devices by addressing their available gate sets and topological constraints.

Command	Description
device read	read info about a quantum device
qc translate	library-based technology mapping
qc opt -t	technology-aware optimization passes
duostra	Duostra qubit mapping for depth or #SWAPs

Data Access and Utilities

qsyn provides various data representations for quantum logic. <dt> stands for any data representation type, including quantum circuits, ZX diagrams, Tableau, etc.

Command	Description
<dt> list	list all <dt>s
<dt> checkout	switch focus between <dt>s
<dt> print	print <dt> information
<dt> <new | delete>	add a new/delete a <dt>
<dt> <read | write>	read and write <dt>
<dt> equiv	verify equivalence of two <dt>s
<dt> draw	render visualization of <dt>
convert <dt1> <dt2>	convert from <dt1> to <dt2>

There are also some extra utilities:

Command	Description
alias	set or unset aliases
help	display helps to commands
history	show or export command history
logger	control log levels
set	set or unset variables
usage	show time/memory usage

License

qsyn is licensed under the Apache License 2.0.

Certain functions of qsyn is enabled by a series of third-party libraries. For a list of these libraries, as well as their license information, please refer to this document.

Reference

If you are using Qsyn for your research, it will be greatly appreciated if you cite this publication:

@misc{Lau_Qsyn_2024,
Author = {Mu-Te Lau and Chin-Yi Cheng and Cheng-Hua Lu and Chia-Hsu Chuang and Yi-Hsiang Kuo and Hsiang-Chun Yang and Chien-Tung Kuo and Hsin-Yu Chen and Chen-Ying Tung and Cheng-En Tsai and Guan-Hao Chen and Leng-Kai Lin and Ching-Huan Wang and Tzu-Hsu Wang and Chung-Yang Ric Huang},
Title = {Qsyn: A Developer-Friendly Quantum Circuit Synthesis Framework for NISQ Era and Beyond},
Year = {2024},
Eprint = {arXiv:2405.07197},
}