What the RIKEN Center for Quantum Computing Does

RQC's mission is to conduct comprehensive research and development towards the realization of fault-tolerant quantum computers and to explore their applications across diverse scientific and societal domains. The center focuses on a multi-pronged approach, investigating various physical systems for qubit implementation and developing the necessary theoretical frameworks and software tools.

Key activities and research thrusts at RQC include:

1. Quantum Hardware Development: RQC is at the forefront of building and improving quantum computing hardware. A significant focus is on:
   • Superconducting Qubits: This is a primary area, with RQC developing increasingly sophisticated superconducting quantum processors. This includes the design, fabrication, and testing of transmon qubits and associated control and readout technologies.
   • Other Qubit Modalities: The center also explores other promising qubit platforms, including photonic quantum computing (utilizing optical systems), silicon-based spin qubits, and potentially other systems like trapped ions or neutral atoms, fostering a diverse approach to hardware development.
2. Quantum Software and Algorithm Development: Alongside hardware, RQC is heavily invested in creating the software stack necessary to operate and utilize quantum computers. This includes:
   • Quantum Algorithm Design: Developing new quantum algorithms and optimizing existing ones for various applications, such as quantum chemistry simulations, materials science, machine learning, and optimization problems.
   • Quantum Error Correction: Researching and implementing quantum error correction codes and fault-tolerant quantum computing architectures, which are crucial for overcoming the inherent fragility of quantum states and enabling large-scale quantum computation.
   • Quantum Control Software: Building software for the precise control and manipulation of qubits.
   • Quantum Simulators: Developing classical software to simulate quantum systems, aiding in the design and verification of quantum hardware and algorithms.
3. Quantum Computer Architecture and Systems Engineering: RQC addresses the systemic challenges of building scalable and reliable quantum computers. This involves research into:
   • Scalable Qubit Architectures: Designing methods to integrate and control a large number of qubits effectively.
   • Quantum-Classical Interfaces: Developing the interfaces needed for quantum computers to work in conjunction with classical high-performance computers (HPC), leading to hybrid quantum-HPC systems.
4. Theoretical Quantum Science: The center conducts fundamental theoretical research in quantum information science, quantum mechanics, and related fields to provide the foundational understanding necessary for breakthroughs in quantum computing.
5. Fostering Collaboration and Open Innovation: RQC actively collaborates with universities, research institutions, and industrial partners both domestically and internationally. This includes joint research projects, personnel exchange, and the creation of collaborative centers. A notable example is the RIKEN RQC-Fujitsu Collaboration Center, which focuses on the joint development of superconducting quantum computers.

"Products" Offered by RIKEN Center for Quantum Computing

As a research institution, RQC's "products" are primarily in the realm of scientific knowledge, technological advancements, and accessible research platforms:

1. Quantum Computing Hardware Prototypes:
   • Superconducting Quantum Computers: RQC has developed and operates its own superconducting quantum computers. For instance, Japan's first domestically built superconducting quantum computer was unveiled by RIKEN. They have progressively increased qubit counts, with notable achievements like a 64-qubit machine and, in collaboration with Fujitsu, a 256-qubit system. These systems serve as testbeds for research and development.
   • Experimental Setups for Other Qubit Platforms: Specialized experimental setups for research into photonic, silicon spin, and other qubit types.
2. Scientific Publications and Intellectual Property: A primary output is a vast body of high-impact research papers published in peer-reviewed journals, detailing new discoveries, theoretical models, experimental results, and technological innovations. Patents arising from these research activities also constitute a key product.
3. Quantum Software and Tools:
   • Open-Source Software: RIKEN often contributes to or releases open-source software tools and libraries for quantum circuit simulation, algorithm development, and quantum machine learning.
   • Proprietary Software: Development of specialized software for controlling their quantum hardware and for specific research applications.
4. Technical Know-how and Expertise: The accumulated knowledge, experimental techniques, and design methodologies developed by RQC researchers represent a significant intellectual product.
5. Trained Personnel: RQC plays a vital role in training the next generation of quantum scientists and engineers through its research programs, postdoctoral fellowships, and collaborations with universities (e.g., joint graduate school programs).

"Services" Offered by RIKEN Center for Quantum Computing

RQC provides several services to the broader scientific community and its collaborators:

1. Access to Quantum Computing Platforms:
   • Cloud Access for Researchers: RQC, often in collaboration with partners like Fujitsu, provides cloud-based access to its quantum computers for researchers and engineers, typically for non-commercial research purposes under joint research agreements. This allows external users to run experiments and test algorithms on state-of-the-art hardware.
   • Testbed Facilities: Their quantum computers serve as valuable testbeds for researchers exploring Noisy Intermediate-Scale Quantum (NISQ) computing and developing new quantum applications.
2. Collaborative Research Opportunities: RQC actively seeks and engages in joint research projects with academic institutions and industrial partners worldwide. This facilitates knowledge exchange and accelerates progress in specific areas of quantum computing.
3. Quantum-HPC Hybrid Platform Development and Access: RQC is involved in initiatives to integrate quantum computers with classical supercomputers like Fugaku (housed at the RIKEN Center for Computational Science, R-CCS). They are developing the hardware and software environments to enable these hybrid computations, offering new avenues for scientific discovery. For example, RIKEN selected Quantinuum's ion-trap quantum computing technology for integration into such a hybrid platform.
4. Workshops, Seminars, and Symposia: RQC organizes and hosts scientific meetings, workshops, and seminars to disseminate research findings, foster discussion, and promote collaboration within the quantum computing community.
5. Educational and Outreach Programs: While primarily a research center, RQC contributes to educating the public and students about quantum computing through various outreach activities, publications, and by making information available through RIKEN's broader communication channels.
6. Support for Quantum Technology Development: RQC provides access to various research equipment and facilities crucial for superconducting quantum computer development and other quantum technologies.

In summary, the RIKEN Center for Quantum Computing is a pivotal national and international hub for quantum computing research and development. It "does" cutting-edge science and engineering across the full stack of quantum computing, from fundamental theory and materials to hardware fabrication, software development, and system integration. Its "products" are primarily new knowledge, advanced quantum computing prototypes, and open research tools, while its "services" focus on providing access to its unique facilities, fostering collaborations, and driving the entire field of quantum information science forward. RQC plays a critical role in Japan's national strategy to become a global leader in quantum technology.