Electrons can be ‘kicked across’ solar materials at almost the fastest speed nature allows, scientists have discovered – challenging long-held theories about how solar energy systems work. The finding could help researchers design more efficient ways of harvesting sunlight and converting it into electricity.

In experiments capturing events lasting just 18 femtoseconds – less than 20 quadrillionths of a second – researchers at the University of Cambridge observed charge separation happening within a single molecular vibration.

“We deliberately designed a system that, according to conventional theory, should not have transferred charge this fast,” said Dr Pratyush Ghosh, Research Fellow, at St John’s College, Cambridge, and first author of the study. “By conventional design rules, this system should have been slow and that’s what makes the result so striking.

“Instead of drifting randomly, the electron is launched in one coherent burst. The vibration acts like a molecular catapult. The vibrations don’t just accompany the process, they actively drive it.”

A femtosecond is one quadrillionth of a second – one second holds about eight times more femtoseconds than all the hours that have passed since the universe began. At that scale, atoms inside molecules are physically vibrating. 

The research, published in Nature Communications, challenges decades of design rules in solar energy research.

Distributed fiber-optic acoustic sensing is an emerging technology that has been used for geophysical exploration, earthquake monitoring and structural health monitoring, etc., with continuous monitoring capability over long fiber spans. However, the technology still suffers from the trade-off between measurement speed and dynamic strain measurement range. Recently, researchers from Huazhong University of Science and Technology (China) and Universidad Técnica Federico Santa María (Chile) have developed a frequency-comb spectrum-correlation reflectometry based distributed fiber-optic acoustic sensing technique, which achieves an order-of-magnitude improvement in frequency response over the state-of-the-art fast frequency scanning methods, meanwhile it achieves more than tenfold enhancement in dynamic strain measurement range in comparison with the existing phase-demodulated systems. This breakthrough represents a new paradigm for distributed fiber-optic sensing and will meet the urgent demands across a wide range of industrial fields.

POSTECH Professor Kilwon Cho’s Team Develops a Wearable Vibration Sensor Capable of Accurately Detecting Minute Physiological Vibrations.

Photonics is gaining momentum as a platform for high-speed AI computing. Researchers in Singapore have demonstrated a passive, ultrafast, and integration-ready all-optical nonlinear activation function using thin-film lithium-niobate nanowaveguides. By achieving highly efficient second-harmonic generation within the data path, the activation arises from a near-instantaneous electronic response. The advance tackles a major obstacle to fully optical neural computation, opening a path to on-chip photonic neural networks that harness the intrinsic speed and bandwidth of light.

Estimating things that exist is generally easy, but when it comes to estimating things that do not exist, it’s more difficult. This is something physicists from Poland and the UK are well aware of. To improve current simulations of high-energy particle collisions, they have developed a more accurate method for estimating the impact of calculations that are... not performed.