For the First Time, a Quantum Computer Simulates the Properties of a Real Magnetic Material
The primary field where quantum computers are expected to operate is that of scientific research, and this is where the greatest efforts are already being concentrated today. It is therefore no coincidence that the first results are starting to arrive: following the discovery of the first "half-Moebius" molecule, researchers from IBM and U.S. research institutions (Oak Ridge National Laboratory, Purdue University, University of Illinois Urbana-Champaign, Los Alamos National Laboratory, and University of Tennessee) successfully used a quantum computer to accurately simulate the properties of a real magnetic crystal.
A Quantum Computer Simulates a Real Magnetic Material
Quantum computers originated from Richard Feynman's idea that it is impossible to simulate reality with classical means because it is quantum and thus requires quantum tools. This idea is proving to be valid, as the devices we have today, albeit imperfect and prone to errors, are already demonstrating their usefulness for making scientific discoveries.
Shortly after the discovery of the first "half-Moebius" molecule, IBM announced that one of its quantum computers had been employed to study the properties of a well-known magnetic material, the fluorinated perovskite KCuF₃. The simulation was conducted using an IBM Quantum Heron processor, while the experimental data was obtained from the Spallation Neutron Source at the Oak Ridge National Laboratory and from the Rutherford Appleton Laboratory in the UK.
The simulation carried out with the quantum device was found to be accurate and in strong agreement with measurements obtained through neutron scattering. This procedure involves bombarding the material with neutrons: by measuring the energy and momentum of these neutrons, it is possible to infer the dynamic and structural properties of the material precisely, since neutrons weakly interact with the material and do not significantly alter its physical state.
However, such measurements require calculating multiple spins in an entangled state, which is particularly difficult to compute with classical tools. "There is a lot of data on neutron scattering in magnetic materials that we do not fully understand due to the limitations of approximate classical methods," stated Arnab Banerjee, assistant professor of physics and astronomy at Purdue University.
The simulation proved to be extremely accurate: according to the study's co-author Allen Scheie, a condensed matter physicist at Los Alamos National Laboratory in the U.S., "this is the most astonishing match I've seen between experimental data and simulation using qubits, and it definitely raises the bar for what can be expected from quantum computers. I am extremely excited about what this means for science."
For some time now, there has been talk of "quantum supremacy," "quantum advantage," and "quantum utility," and it is always said that this moment will come in the future, whether it's about demonstrating that quantum computers have an edge over classical ones or that they dominate in terms of computing power. The last point, that of utility, is perhaps the most concrete and important: if quantum computers could allow us to understand reality and nature even just a little bit better, all the efforts and investments made in their development will have been worth it. And even today, with the discoveries made, it seems that these devices will be of great help to us.