Superfast Computing Method Uses Terahertz Light Pulses

An international team has discovered how to perform superfast data processing using light pulses instead of electricity. The team used magnets to create faster data processing speeds without incurring high energy costs.

Traditionally in magnetic hard drives, the magnetic read/write head uses electrical currents to retrieve information. Researchers from Lancaster University, Regensburg University, Radboud University, and the Russian Academy of Sciences replaced the electricity used to retrieve data with extremely short pulses of light. Each pulse is the duration of one-trillionth of a second and is concentrated by special antennas on top of a magnet.

Using ultrashort pulses of light enables extremely economical switching of a magnet from one stable orientation (red arrow) to another (white arrow). This concept enables ultrafast information storage with unprecedented energy efficiency. Courtesy of Brad Baxley/parttowhole.com.

To demonstrate their method, the researchers pulsed a magnet with ultrashort light bursts at frequencies in the terahertz spectral range, utilizing the coupling interaction between spins and the THz electric field — a discovery made by the team that enables pulses to be strong enough to switch the orientation of a magnet.

The scientists then developed and fabricated a very small antenna on top of the magnet to concentrate and thereby enhance the electric light field. The enhanced strength of the local electric field was sufficient to navigate the magnetization of the magnet to its new orientation in just one-trillionth of a second. The temperature of the magnet did not increase because the amount of energy required for the process was only one quantum (one photon) of the THz wavelength per spin.

“The record-low energy loss makes this approach scalable,” said researcher Rostislav Mikhaylovskiy. “Future storage devices would also exploit the excellent spatial definition of antenna structures, enabling practical magnetic memories with simultaneously maximal energy efficiency and speed.”

Mikhaylovskiy will continue to explore the practical and fundamental speed and energy limits of magnetic recording using the new ultrafast laser at Lancaster University with the accelerators at the Cockroft Institute to generate intense pulses of light that enable switching magnets.

The research was published in Nature (https://doi.org/10.1038/s41586-019-1174-7).