Small scale defined on nano-seesaw
Electrical engineers have developed a nanoscale device that can weigh a single photon and mechanically transport it for the first time.
The discovery could be used for faster and more efficient optical devices for computation and communication.
The novel nanoscale device can capture, measure and transport fundamental particles of light - photons.
The tiny invention is just 0.7 micrometres by 50 micrometres (0.00007 by 0.005 centimeters) and works a little bit like a seesaw.
On each side of the ‘seesaw benches’, researchers etched an array of holes, called photonic crystal cavities. These cavities capture photons that streamed from a nearby source.
Even though the particles of light have no mass, the captured photons were able to play seesaw by generating optical force.
Researchers compared the optical forces generated by the photons captured in the cavities on the two sides of the seesaw by observing how the seesaw moved up and down. In this way, they were able to ‘weigh’ the photons.
The incredible device is sensitive enough to measure the force generated by a single photon, which is about one-seventh of a thousand-trillionth of a kilogram.
The research team also used the seesaw to experimentally demonstrate the mechanical control of transporting light for the first time.
“When we filled the cavity on the left side with photons and leave the cavity on the right side empty, the force generated by the photons started to oscillate the seesaw. When the oscillation was strong enough, the photons can spill over along the beam from the filled cavity to the empty cavity during each cycle,” Professor Mo Li, from the University of Minnesota, said.
“We call the phenomenon ‘photon shuttling.’”
The stronger the oscillation, the more photons are shuttled to the other side.
Currently, the team has been able to transport approximately 1,000 photons in a cycle. For comparison, a 10W light bulb emits 1020 photons every second.
The team's ultimate goal is to transport only one photon in a cycle so that the quantum physics of light can be more easily revealed and harnessed.
The research paper has been published in Nature Nanotechnology.