Hiroshi Horii
Head Of IBM Quantum Japan
Japan
Summary
👤
Senior🎓
Top SchoolHiroshi Horii is a seasoned technology leader and Head of IBM Quantum Japan with over a decade of experience bridging research-grade systems and production-grade software. Holding a Ph.D. in Computer Science from Waseda University, he has led performance optimization efforts across quantum simulation (Qiskit/Aer), JVM-based systems, and transaction-processing stacks at IBM. Known for hands-on backend contributions to prominent open-source projects like Qiskit and OpenQASM, he has improved parameter binding, circuit caching, and language grammar—work that tangibly speeds quantum algorithm simulation. At IBM he has progressed from researcher to Senior Technical Staff Member and now leads Japan’s quantum strategy, combining deep systems expertise with product and business execution. Colleagues describe him as a pragmatic optimizer who translates low-level performance improvements into measurable gains for large-scale quantum workflows.
10 years of coding experience
16 years of employment as a software developer
Doctor of Philosophy (Ph.D.), Computer Science, Doctor of Philosophy (Ph.D.), Computer Science at 早稲田大学 / Waseda University
Japanese, English
Github Skills (13)
grammar10
algorithm10
circuit10
unit-testing10
quantum-computing10
syntax10
lang10
grammars10
qiskit10
python10
antlr10
test-automation10
documentation8
Programming languages (5)
Github contributions (5)
openqasm/openqasm
Apr 2018 - Sep 2021
Quantum assembly language for extended quantum circuits
Role in this project:
Back-end Developer
Back-end DeveloperContributions:16 reviews, 29 commits, 19 PRs in 3 years 6 months
Contributions summary:Hiroshi primarily contributed to the development of the OpenQASM language, focusing on its grammar and syntax. Their work included modifying the grammar to improve its structure, such as uniting the expression hierarchy and adding power expressions. They also addressed bugs related to variable names and operator precedence, while contributing to the documentation.
assembly-languagequantum-circuitsquantum-computingcircuitsextended
Qiskit/qiskit
Aug 2020 - Jul 2021
Qiskit is an open-source SDK for working with quantum computers at the level of extended quantum circuits, operators, and primitives.
Role in this project:Back-end Developer & QA Engineer
Back-end Developer & QA EngineerContributions:3 reviews, 10 commits, 9 PRs in 10 months
Contributions summary:Hiroshi primarily contributed to improving the performance and functionality of the Qiskit library. Their work focused on optimizing parameter binding for the Aer backend, including refactoring and implementing tests to ensure its correct operation. They also addressed bugs related to measurement mitigation and circuit caching, improving the reliability and efficiency of quantum circuit simulations. Furthermore, the user added tests to ensure correctness and added additional features to the existing test suite.
pythonquantum-circuitsquantum-computingcircuitsquantum-circuit
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