Physicist Prosen helps unlock quantum computer utility in breakthrough finding

Ljubljana, 5 April - Slovenian mathematical physicist Tomaž Prosen, along with researchers from Google's Quantum AI lab, has demonstrated the first practical application of a quantum computer. The team successfully conducted a quantum simulation of a quantum material and discovered a completely new type of transport in the process.

The development heralds a new, quantum computer-backed era for research in theoretical physics, with Prosen, a professor at the Faculty of Mathematics and Physics at the University of Ljubljana, labelling quantum computers a technology of the future.

Based on the fundamental principles of quantum mechanics, these machines perform operations using quantum bits, or qubits. Compared to classical computers, quantum computers harbour significantly greater processing power.

Despite ongoing efforts by researchers worldwide to achieve practical applications for quantum computers in science, challenges remain. These include sensitivity to errors and limitations in the stability of qubits. However, the recent research by Prosen and the wider team, published last Thursday in the prestigious scientific journal Science, represents a successful demonstration of using a quantum computer to simulate a quantum system.

Prosen, a two-time winner of the European Research Council's prestigious Advanced Grant, told the STA that the team utilized Google's Quantum AI lab's 46-qubit quantum computer to simulate a model of a quantum material with near-negligible errors. Notably, simulating this material using traditional classical supercomputers would be incredibly difficult.

The computer successfully simulated the dynamics of a model commonly used in quantum mechanics and statistical physics to study the magnetic properties of materials - specifically, the dynamics of the Heisenberg spin chain.

During the simulation, they unexpectedly discovered a completely new type of transport, faster than heat conduction (diffusion) but slower than sound waves (ballistic transport). This newly identified phenomenon has been named superdiffusive transport.

The results confirmed previous theoretical predictions by Prosen's colleagues at the faculty. Already years ago, Prosen, Marko Žnidarič, Enej Ilievski, and their doctoral students theoretically predicted the existence of this type of transport, described in many respects by the Kardar-Parisi-Zhang equation from classical statistical physics.

This equation, among other applications, describes the growth of snowflakes. In this case, Prosen and his team not only confirmed its existence through experimentation but also observed significant deviations from the equation's predictions in certain aspects.

"We thus discovered the existence of a new universality class in nonequilibrium statistical physics which we are not familiar with yet and which requires further research," said Prosen.

"This discovery marks the dawn of a new era for research in theoretical physics, utilising quantum computers as truly valuable tools for exploring new phenomena and concepts. It reminds me somewhat of the situation 70 years ago, after World War II, when physicists began using digital computers. This shift opened up vast new areas in theoretical physics, such as chaos theory, soliton physics, and many others," added Prosen.

He further highlighted the field of high-temperature superconductor theory as a potential area where quantum computers could lead to significant advancements.

Anton Ramšak, the Ljubljana University's vice-rector for research and development, hailed the publication in Science as a confirmation of the university's excellent work in the field of quantum technologies.

"This is also significant for science as a whole," he added. "After years of anticipation and promises surrounding quantum computing, we are now witnessing one of the first major scientific findings achievable only through the use of a quantum computer," Ramšak said.