Excitons Enable Low-Energy Quantum Material Transformation

Quantum materials researchers have bypassed a major technical barrier by using excitons instead of high-energy lasers to reshape material properties. A study published in Nature Physics (2026) by researchers from the Okinawa Institute of Science and Technology (OIST) and Stanford University demonstrated excitonic Floquet engineering in 2D semiconductors.

The team used time-resolved angle-resolved photoemission spectroscopy (TR-ARPES) to isolate excitonic effects, achieving Floquet band hybridization with 10 times less light intensity than traditional optical methods.

The method leverages excitons—bound states of electrons and holes within the material—to enable stronger coupling than photons. As the authors note, "Excitons couple much stronger to the material than photons..."

This approach allows for precise manipulation of quantum states without the energy demands of femtosecond laser pulses. The 200 femtosecond delay in measurements provided critical evidence for separating excitonic contributions from light-driven responses.

Compared to conventional light-driven Floquet engineering, the exciton-driven method reduces required energy intensity by an order of magnitude.

The team, comprising 18 researchers from eight institutions across five countries, described the achievement as "opened the gates to applied Floquet physics."

While the results represent a significant advancement, the authors caution that further studies are needed to validate long-term stability and scalability of the technique.