June 15, 2026 -- What would it take to instantly transform a material from an electrical insulator into a conductive state without ever touching it? Using ultrafast laser pulses and powerful X-rays, scientists at the National Synchrotron Light Source II (NSLS-II) — a U.S. Department of Energy (DOE) Office of Science user facility at DOE’s Brookhaven National Laboratory — developed a methodology to generate “hidden” phases and understand why they work. This research not only reveals a hidden state of matter and its fundamental interactions but also points toward new ways to control materials for future electronics and quantum technologies. Their work was recently published in Physical Review X.

At the heart of the research is an interesting class of quantum materials called magnetoresistive manganites. Under the right conditions, their properties and behaviors can change completely with external stimuli. In this case, the team used short bursts of laser light lasting 100 femtoseconds (one hundred quadrillionths of a second) to “switch” a material from an insulating state, where electricity cannot flow, to a conductive one.

“The switching mechanism is really fast, much faster than any electronic devices we have today,” said Jonathan Pelliciari, a beamline scientist at the Soft Inelastic X-ray Scattering (SIX) beamline. “Instead of using electrodes or currents though, we simply use light.”

While previous studies had shown that shining light on certain materials could trigger such transformations, what actually happens inside the material, and why it happens, has remained largely unclear. To answer those questions, the team employed two complementary X-ray techniques: resonant inelastic X-ray scattering (RIXS) and X-ray absorption spectroscopy (XAS) at the SIX beamline. While the laser pulse triggers the change, the X-rays probe the material at the microscopic level, revealing how its electronic structure evolves. Together with in-situ transport measurements, these tools demonstrate that light drives the material into a previously inaccessible nonthermal conductive state that differs from the metallic phase produced by conventional heating. Because this phase cannot be reached through ordinary thermal processes, researchers describe it as a “hidden” phase.

Stepping into the quantum realm

Even more intriguing, the light-induced state doesn’t immediately disappear. Instead, it persists long after the laser pulse is gone, indicating a more fundamental thermodynamic stability property. Once you switch the material, you keep the same state for a while until another external stimulus is applied to revert it back. The ability to switch and hold a material in a new state suggests possible applications in data storage or computing, where information is encoded in distinct physical states. This research also connects to the growing field of quantum information science, which aims to harness unusual quantum properties to create faster and more powerful computers and devices through the development of qubits – quantum systems that require two different physical states that can be triggered to switch on demand.

“Light offers a more direct and selective way to switch a quantum material than conventional approaches based on thermal cycling or static electric and magnetic fields,” said Shiyu Fan, a beamline scientist at the Inelastic X-ray Scattering (IXS) beamline and lead author of this work. “Instead of simply warming the sample, the laser can drive the system into a distinct nonthermal state. The ability to control a material’s phase while preserving its correlated quantum character could be important for future quantum-device design.”

There are practical advantages, too. Traditional thermal methods that are currently used to change a material’s state can disrupt quantum behavior by washing out delicate correlated states, leading to less reliable devices. Ultrafast laser pulses, by contrast, can trigger phase changes without relying solely on bulk heating, offering a more selective route to control the material. While the current system still requires heating to reset the material back to its original state, future work may explore ways to reverse the process using different wavelengths of light, bringing researchers closer to fully controllable, light-driven devices.

Beyond the scientific findings, the experiment highlights the integration of advanced laser systems across multiple beamlines, a capability that is developing and growing at NSLS-II. The portable ultrafast laser used in this study can be shared among different experimental stations, enabling a wide range of time-resolved measurements.  These capabilities allow researchers to study not only how materials are structured, but also how electrons and atoms move and interact during ultrafast transformations.

The approach also complements research at other major facilities, such as free-electron lasers, which excel at capturing extremely short-lived states. At NSLS-II, scientists can instead focus on longer-lived phases with exceptionally high energy resolution, offering a highly detailed view of material behavior.

As researchers continue to explore how light can reveal and control hidden phases of matter, new paths emerge to explore novel electronics, quantum-enabled devices, and faster computing.

This work was supported by a Laboratory Directed Research and Development (LDRD) project from Brookhaven National Laboratory and a Facility Improvement Project (FIP) from NSLS-II. The development of the laser system involved the teams at the SIX beamline, Coherent Soft X-ray Scattering (CSX) beamline, and the Magnetic, Ellipsometric, Time-resolved Infrared and Nanospectroscopies (MET) beamline. This research also used the wire bonding machine at the Center for Functional Nanomaterials, a DOE Office of Science User Facility at DOE’s Brookhaven National Laboratory.