Recently, the research group led by Associate Professor Jianxin Chen at the Quantum Software Research Center, Department of Computer Science, Tsinghua University, in collaboration with Fei Yan’s team from the Beijing Academy of Quantum Information Sciences, achieved a significant breakthrough in quantum computer architecture. The team pioneered the development of AshN, a novel instruction set architecture that enables direct programming of arbitrary two-qubit quantum gates. The related research findings, titled ‘Efficient implementation of arbitrary two-qubit gates using unified control,’ were subsequently published in Nature Physics on August 15.

Assistant Researcher Zhen Chen and Associate Researcher Weiyang Liu from the Beijing Academy of Quantum Information Sciences are co-first authors of the paper, while Associate Professor Jianxin Chen and Researcher Fei Yan serve as the corresponding authors.

Research reviewers praised the paper. One reviewer summarized, “The main insight is the simultaneous application of flux control and microwave drives, allowing one to navigate the entire Weyl chamber without additional overhead. The combination of flux and microwave is highly nontrivial and underexplored.”

In conventional quantum computers, complex operations are typically decomposed into sequences of CNOT and single-qubit gates. This approach is not only inefficient but also prone to additional operational errors. To address this fundamental challenge, Chen’s group has developed the AshN quantum instruction set architecture, which employs a collaborative control scheme that integrates flux control with microwave driving. Through multi-parameter coordination within a unified control framework, AshN achieves full coverage of all equivalence classes of two-qubit unitary operations.

The core advantages of this architecture are reflected in three key aspects. First, it enables the direct implementation of arbitrary two-qubit unitary operations through a unified control pulse, entirely eliminating the cumbersome gate-level decomposition of traditional methods. Second, compared with conventional schemes, it substantially reduces the number of required operations and thereby mitigates error accumulation. Third, under reasonable assumptions, the architecture ensures the shortest possible evolution time, facilitating high-precision physical implementation. The AshN architecture has been successfully deployed and experimentally validated on the superconducting qubit platform at the Beijing Academy of Quantum Information Sciences, demonstrating that this innovative instruction set can directly enhance the performance of existing superconducting quantum chips.

The effect of implementing common two-qubit gates such as CNOT, iSWAP, and B with AshN instruction microarchitecture.

The theoretical framework of the AshN instruction set was showcased by Chen’s group at ASPLOS 2024, the premier conference in computer architecture. This milestone highlights the deep integration of computer science and quantum physics. The work not only drives a fundamental shift in the quantum computing paradigm but also introduces new research directions and technical approaches spanning from hardware architecture to high-level algorithms, as well as implementation and compilation optimization. Building on this foundation, Chen’s group is now working on new implementation schemes for fault-tolerant quantum computing based on the AshN microarchitecture.

Paper links:

Instruction set theoretical scheme:

https://dl.acm.org/doi/10.1145/3620665.3640386

Instruction set experimental verification:

https://www.nature.com/articles/s41567-025-02990-x

Editor: Li Han