Stopping Light In Its Tracks Brings Quantum Computing Closer

October 1, 2016

Quantum computing is the next epic leap forward in the evolution of digital technology and communication. Using light, these systems allow for calculations far beyond the capacity of conventional computers. Physicists have now successfully stopped light, a level of control over photons that brings optical quantum computing significantly closer.

quantum-computing[Image source:ANU TV]

Researchers out of the Australian National University (ANU) are working on controlling how light moves. Building upon a computer simulation that showed it was possible to effectively stop light, the team designed a ‘light trap’. This ingenious apparatus worked by shining infrared lasers into a cloud of ultra-cold atomic vapour.

Jesse Everett, lead researcher from the Research School of Physics and Engineering (RSPE) and ARC Centre of Excellence for Quantum Computation and Communication Technology at ANU, said:

“It’s clear that the light is trapped, there are photons circulating around the atoms. The atoms absorbed some of the trapped light, but a substantial proportion of the photons were frozen inside the atomic cloud.”

The system being studied is highly complex. ANU research team leader, Associate Professor Ben Buchler, highlighted the degree of control required of the light-trap experiment: “Our method allows us to manipulate the interaction of light and atoms with great precision.”

The future of quantum computing will rely upon our ability to control the movement of light. Everett listed the practical applications of photon manipulation as including medicine, defence, telecommunications, and financial services. “Optical quantum computing is still a long way off, but our successful experiment to stop light gets us further along the road,” he said.

The research team has found a way to increase the ability of photons to interact. Team member Dr Geoff Campbell said that, while atoms interact with one another easily, photons generally do not, due to the velocities at which they travel. He explained:

“Corralling a crowd of photons in a cloud of ultra-cold atoms creates more opportunities for them to interact. We’re working towards a single photon changing the phase of a second photon. We could use that process to make a quantum logic gate, the building block of a quantum computer.”

Read the team’s research findings in their newly published Nature Physics paper.

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