Scientists at Oak Ridge National Laboratory used lasers and neutrons to observe a non-equilibrium quantum state in a magnetic material.
Key facts
- •The study was published in Nature Communications in 2026.
- •Researchers used rapid laser pulses and ORNL's Spallation Neutron Source to study the material.
- •The material violated the physical rule of detailed balance under laser pulsing.
- •The nonequilibrium state persisted as a long-lived steady state rather than fading away.
- •The team included ORNL researchers Chengyun Hua, Barry Winn, and Alan Tennant.
Researchers at the Department of Energy's Oak Ridge National Laboratory (ORNL) and collaborators used lasers and neutrons to observe a long-lived quantum state in a magnetic material. The study, published in Nature Communications, demonstrates how a laser can push a magnetic system out of its normal state and how neutrons can reveal the details of that state. The findings show that the new state can persist at low energy rather than transiently fading away.
Experimental Methodology
The team studied magnons, which are quantum quasiparticles whose wavelike excitations are critical to magnetic behavior in materials. In the experiment, rapid laser pulses drove the material out of its normal resting state. ORNL's Spallation Neutron Source, a DOE Office of Science user facility, allowed the team to study the microscopic details of the magnetic behavior inside the material. This combined approach is not typically used for nonequilibrium studies.
Violation of Detailed Balance
The measurements showed that the material violated a physical rule of matter called "detailed balance." In a system at rest, this rule links energy-gaining and energy-losing events in a predictable way. Under the rapid laser pulses, that balance broke, with neutron data showing extra signals only on one side. The lopsided excess magnons persisted, indicating a long-lived nonequilibrium steady state sustained by periodic laser pulsing rather than a brief heating effect.
Implications for Quantum Science
ORNL's Chengyun Hua stated that no one before has directly probed a detailed balance violation in a condensed matter system. The observation makes the system a strong platform for studying other nonequilibrium quantum physics in real time. The insights could help guide future work on quantum materials, coherent transport, and low-loss electronics, providing a new benchmark for what neutron scattering can reveal when materials are actively driven.
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This article was independently rewritten by ManyPress editorial AI from reporting originally published by Phys.org.
