Four researchers from Japan's RIKEN utilized two small-scale quantum computers to simulate quantum information scrambling, an important quantum information process. This achievement demonstrates the potential applications of future quantum computers. The results were published in the journal Physical Review Research.

Quantum computers are still in their early stages, with applications just beginning. However, once they mature as a technology, they will fundamentally transform the field of computing.

One possible application of quantum computers is simulating the scrambling of quantum information—a key phenomenon involving information propagation in quantum systems ranging from strange metals to black holes.

Once information is encoded in part of a quantum system, it becomes diluted over time through various processes and eventually spreads across the entire system.

The original information is not lost, but reconstructing it becomes far more difficult because access to the entire system is required. The most outstanding quantum information scrambler is a black hole, which serves as the ultimate shredder of quantum information.

Understanding how information scrambling occurs is crucial for addressing fundamental problems in quantum physics.

Kazuhiro Seki from RIKEN's Quantum Computing Center (RQC) stated: “We are very interested in quantum information scrambling because we can use it to perform additional computations, such as statistical physics calculations.”

One way to study quantum information scrambling is through simulation, and quantum computers can provide assistance because they are better suited for such simulations than classical computers.

Now, Seki and Seiji Yunoki, also from RQC, together with two colleagues, used two quantum computers with 20 quantum bits (the quantum equivalent of bits) to simulate quantum information scrambling circuits.

For the simulation, the researchers accessed state-of-the-art quantum computers via the cloud, which are based on trapped-ion qubits. They performed three simulations using the quantum computers, including creating scrambled states and using them to carry out quantum statistical mechanics calculations.

Although powerful classical computers can perform such simulations, the complexity of the simulations is approaching the regime where quantum computers become indispensable for these types of calculations.

“In this study, we only used 20 qubits for the simulation,” Yunoki said. “If we were to perform similar calculations with more than 50 qubits, it would likely become too difficult for classical computers to handle.”

In February 2025, RIKEN installed a 20-qubit ion-trap quantum computer. “We hope to upgrade it in the coming years to have around 50 qubits,” Yunoki noted.