Japan’s First Trapped Ion Quantum Computer Startup Takes Flight

Qubitcore, a spinoff from the Okinawa Institute of Science and Technology (OIST), completed its pre-seed funding round in January 2025. Founded in July 2024, the startup aims to realize distributed quantum computing systems by combining trapped ion technology with micro optical resonators, targeting Japan’s first commercial deployment of trapped ion quantum computers.

CEO Ryuta Watanuki holds a PhD in condensed matter physics from Yokohama National University and served as a project researcher at the University of Tokyo and assistant professor at Yokohama National University before venturing into patent technology commercialization. He also has experience taking over, rebuilding, and selling a healthcare and pharmacy business inherited from relatives.

Amid the quantum computing “gold rush,” why is the company betting on Japan-made trapped ion technology, and what future does Qubitcore envision? We spoke with Watanuki to find out.

From Researcher to Entrepreneur

Watanuki’s entry into quantum computing was far from planned. Originally serving as faculty (assistant professor) at Yokohama National University conducting research and education in low-temperature condensed matter physics, he developed and patented a novel phase detection (demodulation) signal separation technology during joint research with the University of Tokyo on ultra-high-speed precision magnetoresistance measurement. This technology could be applied to “virtually any application involving wave manipulation,” including Wi-Fi, mobile phones, MRI systems, and millimeter-wave radar for autonomous vehicles.

Initially, Watanuki launched a medtech startup aiming to achieve MRI imaging speeds 60 times faster, believing that “body scans completed in just a few minutes would greatly benefit patients.” However, technical validation revealed that his approach “couldn’t be applied to MRI systems.” The technical difficulties of signal separation and safety constraints of the equipment made it impossible to achieve performance improvements suitable for practical hospital use, leading him to abandon MRI commercialization. Subsequently, Watanuki explored business pivots but encountered strategic disagreements with his CTO, ultimately deciding to dissolve the company just two and a half months after its founding.

Immediately after deciding to dissolve the company, Watanuki reported the closure to Ryosuke Kimura from Lifetime Ventures, who had been serving as the main mentor in Yokohama City’s YOXO accelerator program (and would later become an investor). Kimura made a pivotal proposal.

Kimura-san said, “I understand. So if you don’t have your next steps decided, Lifetime Ventures runs an OIST partnership fund—why don’t we create a company together based on OIST technology?” At that point, everything would normally be over, but Kimura-san was intrigued.

I was originally a physicist and had long been interested in quantum computers, even though it was outside my field. This sector also had momentum building. I’d heard that Professor Nemoto (Kae, Nemoto, Director of the OIST Center for Quantum Technology) had established a center, so we decided to explore opportunities in quantum research labs. (Watanuki)

Following Kimura’s suggestion, Watanuki focused on Associate Professor Hiroki Takahashi’s trapped ion research at OIST. Trapped ion systems trap multiple ions in electric fields within a vacuum and manipulate individual ions with lasers, achieving extremely high control precision. This approach offers superior quantum computation with lower error rates compared to other methods and represents one of the most advanced practical research areas globally.

In the United States, IonQ had achieved SPAC listing, and Quantinuum, spun out from Honeywell, had built substantial development achievements. However, in Japan, “despite cutting-edge fundamental research on trapped ions and brilliant researchers, there was no movement toward quantum computer social implementation,” presenting significant commercialization opportunities.

Inviting Professor on Board as CSO

In June 2023, Watanuki arranged a meeting with Associate Professor Hiroki Takahashi through OIST Innovation. Initially, colleagues suggested that “Professor Takahashi probably isn’t interested in startups—he’s a pure physics researcher,” but Watanuki persistently made his case.

He argued that “involving industry players would help energize the entire field” and that “introducing risk capital beyond government grants from KAKENHI and JST would attract diverse talent, benefiting both industry and providing feedback to academia.” These discussions gradually shifted Takahashi’s perspective.

Takahashi’s participation as a C-level executive represented an unprecedented decision for OIST. Potential conflicts of interest with his public position required careful consideration, but after approximately 18 months of deliberation, Takahashi committed to deep involvement and officially joined as Chief Science Officer (CSO) in October 2024.

This was unprecedented for OIST. Having a PI (Principal Investigator)—someone who leads a research lab—join as core company personnel had never been done or approved before. But Professor Takahashi’s personal and research networks are irreplaceable, and his expertise is essential for our business operations. (Watanuki)

Takahashi serves as project manager for JST’s Moonshot R&D Program Goal 6, which aims to develop “fault-tolerant universal quantum computers that will dramatically advance economy, industry, and security by 2050,” leading ion trap quantum computer development.

Takahashi brings unique expertise, having earned his PhD researching optical quantum computers at the University of Tokyo, studied trapped ion systems at the University of Sussex in the UK, and researched superconducting quantum computers back at Tokyo University. Globally, he’s an extremely rare researcher with experience across all three quantum computing approaches, according to Watanuki.

Quantum computer development requires deep knowledge rooted in fundamental physics research. Commercialization involves an inseparable relationship between basic research and implementation development—this is common across quantum computing startups worldwide. Therefore, having researchers like Professor Takahashi deeply involved is essential for quantum computing startup success. After explaining this necessity to OIST leadership, which took considerable time, they ultimately responded positively, allowing us to proceed with this structure. (Watanuki)

This 18-month persuasion and trust-building process represented more than just talent acquisition. It established a precedent at OIST, a world-class research institution, and created a new model for industry-academia collaboration in Japan’s quantum computing sector.

Trapped Ion Technology’s Competitive Edge

Qubitcore’s chosen trapped ion approach offers distinct advantages over alternative quantum computing methods. Watanuki explains the underlying physics in detail.

Ion trapping involves bringing individual atoms into a vacuum and ionizing them with lasers—giving them an electric charge—then suspending and trapping them using electric fields. This creates a completely isolated environment, and since we’re using electric forces for trapping, the trap strength is extremely powerful. This isolation from external influences allows stable maintenance of quantum states—that’s our key advantage. (Watanuki)

This structure enables quantum bits with long coherence times and high-fidelity operations and measurements, resulting in “dramatically reduced error rates.” Unlike superconducting quantum bits, which require drawing electrical circuits with metal traces on substrates and inevitably involve physical contact, trapped ion systems achieve near-complete isolation from the external environment, providing overwhelming advantages.

Consider Schrödinger’s famous thought experiment—the cat in the box exists in superposition, simultaneously alive and dead, until observed. The moment you look, the superposition collapses into a definite state. Quantum computers work similarly—external stimuli or observation destroys quantum states. Trapped ion technology’s ability to maintain quantum states for extended periods in excellent condition is one of our greatest advantages. (Watanuki)

Technical maturity represents another major strength of trapped ion systems. Ion trap research spans 70 years, with quantum computing applications studied for 20-30 years. Basic physics is largely understood, with few major unknowns, leaving remaining challenges concentrated in engineering (implementation technology).

This contrasts with relatively newer approaches—such as silicon spin qubits or neutral atoms—where fundamental physics questions remain unanswered. Trapped ion technology has fewer such gaps. (Watanuki)

The competitive landscape shows American companies IonQ and Quantinuum leading commercial development. IonQ went public on the New York Stock Exchange via SPAC in 2021, while Quantinuum operates with substantial backing from parent company Honeywell.

However, excluding China, no companies in Japan or the broader Asia-Pacific region were pursuing commercial trapped ion quantum computing. “Japan represented a complete blank slate,” Watanuki analyzes.

First, established players like IonQ and Quantinuum had already demonstrated commercial viability in the West, eliminating the risk of building markets from zero. Second, Professor Takahashi’s technology showed clear advantages over other approaches with bright implementation prospects. Third, complete absence of activity in Japan and the Asia-Pacific region excluding China. Meeting all three criteria provided strong justification for commercialization. (Watanuki)

This situation presents significant business opportunities for Qubitcore.

Clear Path to 2030 Commercialization

Qubitcore’s proprietary technology addresses traditional trapped ion scalability limitations through distributed architecture. The company aims to realize distributed quantum computing systems by combining trapped ion technology with optical resonators.

Specifically, the approach integrates trapped ion modules with optical resonators and interconnects them via photonic links in a distributed quantum computing architecture.

Conventional trapped ion modules operate standalone, which has been considered a scalability weakness. By 2029, we’ll adopt photonic links and optical quantum interconnects. We’ll connect multiple trapped ion modules—currently used individually—through optical fiber connections and optical switches, enabling unlimited scaling. (Watanuki)

This distributed approach enables design architectures targeting 1,000+ qubit scales, creating pathways for large-scale systems previously impossible with conventional trapped ion methods.

Qubitcore has established a phased commercialization roadmap. Plans include unveiling a first-generation testbed for quantum error correction research in 2028, followed by a second-generation system demonstrating scalability to 1,000+ qubits in 2029.

These are quite ambitious targets. We could achieve basic functionality by 2028, but simply launching commercial operations would lack sophistication. As latecomers, we want to spend an additional two years ensuring our 2030 commercial system demonstrates a compelling vision of the future. (Watanuki)

Initial commercial deployment customers will likely be public research institutions. Currently, they’re exploring partnerships with the newly established Global Research Center for Quantum AI Technology Business Development (G-QuAT) at the National Institute of Advanced Industrial Science and Technology (AIST) in Tsukuba. The company is also advancing partnership discussions with Yokohama and Kawasaki cities while exploring government collaborations.

Global Expansion Challenge

The company has just completed its pre-seed round and plans to pursue seed funding within this year. Watanuki attributes Japan’s quantum computing lag primarily to “insufficient funding.”

Quantum hardware startups require completely different scales of capital compared to SaaS and other software startups. Leading Western quantum hardware startups commonly raise millions to over ten million dollars even in early stages.

Japan lacked VC culture for such large investments, which is why no hardware startups existed until last year. Currently, Japan’s only operational quantum computer remains the superconducting system developed jointly by RIKEN, Osaka University, and Fujitsu. 

Building quantum computers requires substantial funding for clean rooms, processing equipment, development and manufacturing environments, and component procurement. (Watanuki)

Talent acquisition represents the greatest challenge for quantum computing ventures. Japan particularly lacks researchers in trapped ion and adjacent AMO (atomic, molecular, and optical) physics fields. Therefore, the company actively recruits international talent. Foreign nationals already comprise roughly half the team, including a Greek engineer currently undergoing immigration procedures. However, compensation represents the biggest barrier to international recruitment. Competing with Western salary levels requires significant funding capacity.

The current team includes six research personnel (including one professor who left Osaka University and one OIST PhD graduate) and four business personnel, totaling ten people. “Once funding is secured, we’ll aggressively scale hiring” alongside technical development, Watanuki notes. Beyond funding and talent challenges, global expansion represents a crucial strategic priority.

Currently, Qubitcore envisions business expansion into Europe and the Asia-Pacific region, exploring partnerships with research institutions and companies across various countries. They’re particularly examining possibilities for technical exchanges and joint research with nations active in quantum technology development.

Quantum computing faces information security considerations similar to AI. However, Japan’s domestic market alone cannot sustain the business, making global expansion essential, Watanuki points out.

While pursuing global expansion, they carefully consider information security perspectives. With foreign nationals comprising roughly half the team, they monitor developments across various countries while pursuing healthy and sustainable business operations.

The Japanese government has yet to clarify security strategies for domestic quantum computer technology, but Watanuki carefully monitors future developments.

In AI and semiconductors, Japan’s national efforts seemed reactive. Even generative AI only began receiving serious policy attention a few years ago. Japan already lags behind the West in quantum computing. Therefore, applying lessons from AI and semiconductors toward earlier strategic national initiatives is crucial. We hope for early action to prevent delayed responses that compromise competitiveness. (Watanuki)

This strong sense of urgency drives Qubitcore’s rapid business development. While navigating the complex balance between information security and global expansion, they work to establish presence as a Japan-originated quantum computing company in global markets.

Qubitcore’s vision extends beyond technology development to elevating Japan’s entire quantum computing industry, targeting practical quantum computers for drug discovery, advanced materials design, climate simulation, and future AI model training acceleration—solving challenges that require enormous resources with conventional computers.