Researchers from Harvard University and the Paul Scherrer Institute (PSI) have stabilized short-lived quantum states in materials using bright X-ray pulses from the SwissFEL X-ray laser. Their study, published in Nature Materials, demonstrates a metastable electronic state in a copper oxide compound that persists for several nanoseconds—about a thousand times longer than typical light-induced states.
The team studied Sr₁₄Cu₂₄O₄₁, a nearly one-dimensional “cuprate ladder” material. Normally, its electronic symmetry prevents charge transfer between structural units. By using laser pulses to break this symmetry, charges tunneled from one unit to another, creating a trapped metastable state that could be measured before decaying.
To capture this transition, the researchers used time-resolved Resonant Inelastic X-ray Scattering (tr-RIXS) at the Furka endstation at SwissFEL. This technique enabled them to directly observe ultrafast electronic motion and magnetic, electric, and orbital excitations.
The experiment was the first conducted by a user group at Furka and demonstrates a new method for exploring non-equilibrium states in quantum materials. The upgraded endstation will allow further studies into complex excitations, paving the way for future optoelectronic devices and quantum information storage.