World's 1st hybrid quantum supercomputer goes online in Japan

Engineers in Japan have switched on the world's first hybrid quantum supercomputer.

The 20-qubit quantum computer, called Reimei, has been integrated into Fugaku — the world's sixth-fastest supercomputer. The hybrid platform will work to tackle calculations that can take classical supercomputers much longer to process.

The machine, which is housed at the Riken scientific institute in Saitama, near Tokyo, will be used primarily for physics and chemistry research, representatives from Quantinuum, the makers of Reimei, and Riken said in a joint statement.

Quantum computers could one day overtake classical computers, with the potential to complete calculations in minutes or seconds that would otherwise take today's most powerful machines millions of years. However, until quantum computers are large and reliable enough, scientists say that integrating their capabilities into supercomputers can be a stopgap.

Unlike most quantum computers that use superconducting qubits, Reimei uses trapped-ion qubits. This involves isolating charged atoms, or ions, in an electromagnetic field — known as an ion trap — and using lasers to precisely control their quantum state.

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This enables the scientists to manipulate the ions so they can be used as qubits that store and process quantum information. Trapped ion qubits encourage more connections between qubits and longer coherence times, whereas superconducting qubits have faster gate connections and are easier to fabricate on chips.

Riken representatives said they chose Quintinuum's quantum computer for the integration because it has a unique architecture that physically moves qubits. This process of "ion shuttling" allows qubits to be moved around a circuit as required, allowing for more complex algorithms.

Error-correcting system

Qubits are inherently "noisy," so to effectively scale up quantum computers, scientists are developing error-correction techniques to increase the fidelity of qubits.

In Reimei, the physical ion qubits have been grouped to create "logical qubits" — meaning a set of physical qubits that store the same information in several places. Logical qubits are a key route to achieving a desired reduction in qubit errors, because distributing the information in different places spreads out the points of failure, meaning a qubit failure does not disrupt an ongoing calculation.

Quaintinuum previously achieved a breakthrough in creating a logical qubit with an error rate 800 times lower than physical qubits, which it integrated into its quantum computing processors.

While Reimei-Fugaku is the first fully operational, integrated hybrid system, other companies have previously tested such systems. In June 2024, IQM integrated a 20-qubit quantum processor into the SuperMUC-NG supercomputer in Garching, Germany.

That system, however, is still in the testing phase, with no confirmed public date when it becomes fully operational. In October, IQM representatives announced the company would integrate a 54-qubit system into the supercomputer in the latter half of 2025 followed by a 150-qubit chip in 2026.