From the power of magnetism to controlling the speed of light
Imagine driving across a bridge that normally takes one second. But this time, it takes eight minutes longer than expected. On the way back, you somehow arrive at the other side eight minutes before you even reach the bridge — as if you’ve stolen time! Now replace the car – and yourself – with a microwave pulse. The bridge would then be a “nonreciprocal device”, as physicists call it. It slows the speed of light in one direction and speeds it up in the other, all in one system.
Jerry Lu, PhD Student; Jiguang Yao, PhD Student; both from the Department of Physics and Astronomy
You might think controlling the speed of light directionally is a far-fetched idea. But what seems like science fiction is very much the reality of two PhD students’ work. Jiguang Yao and Jerry Lu are PhD students at the UM Faculty of Science. They are both members of Dr. Can-Ming Hu’s lab at the Department of Physics and Astronomy. They also collaborate with Dr. Greg E. Bridges from the Department of Electrical and Computer Engineering.
The Physical Review Letters recently published their work as an Editor’s Suggestion. Their work was also Featured in Physics via a Viewpoint article. In their paper, the team advances the pursuit of controlling the speed of light by achieving both slow and fast light within a single system.
They precisely control the group velocity of a microwave pulse through the power of magnetism to realise nonreciprocal propagation. This is one of the oldest disciplines in physics. This means, while the pulse is delayed in one direction, it advances in the other direction. It creates the possibility of one side seeing the pulse in slow motion, while the other sees it in fast motion.
“It’s mainly important for information technology that uses light as the medium. In these kinds of technologies, the information is carried by the light pulse. So, our technology allows you to control the pulse speed to regulate the information. It also has the potential to enable a completely new type of logical devices”, says Yao.
Watch the full video on the Faculty of Science’s YouTube channel to learn more.