Gurmukh Singh

Toronto, Dec 16 Indian-origin researcher Sanjeev John and his colleague Xun Ma of the University of Toronto have discovered new behaviour of light which could lead to cooler and faster computing.

The two quantum optics researchers have discovered "new behaviours'' of light changes within photonic crystals that could lead to faster optical information processing and compact computers that don't overheat.

"We discovered that by sculpting a unique artificial vacuum inside a photonic crystal, we can completely control the electronic state of artificial atoms (light) within the vacuum,'' lead author Xun Ma was quoted as saying in a statement here on Tuesday.

"This discovery can enable photonic computers that are more than a hundred times faster than their electronic counterparts, without heat dissipation issues and other bottlenecks currently faced by electronic computing,'' said Ma.

Added Sanjeev John, "We designed a vacuum in which light passes through circuit paths that are one one-hundredth of the thickness of a human hair, and whose character changes drastically and abruptly with the wavelength of the light.

"A vacuum experienced by light is not completely empty, and can be made even emptier. It's not the traditional understanding of a vacuum.''

Ma said,"In this vacuum, the state of each atom -- or quantum dot -- can be manipulated with color-coded streams of laser pulses that sequentially excite and de-excite it in trillionths of a second.

"These quantum dots can in turn control other streams of optical pulses, enabling optical information processing and computing.''

The researchers, whose original aim was to gain a deeper understanding of optical switching as part of an effort to develop an all-optical micro-transistor that could operate within a photonic chip, ended up discovering a new and unexpected dynamic switching mechanism.

Their research also led to the discovery of corrections to one of the most fundamental equations of quantum optics, known as the Bloch equation.

Said John, "This new mechanism enables micrometer scale integrated all-optical transistors to perform logic operations over multiple frequency channels in trillionths of a second at microwatt power levels, which are about one millionth of the power required by a household light bulb.

"That this mechanism allows for computing over many wavelengths as opposed to electronic circuits which use only one channel, would significantly surpass the performance of current day electronic transistors.''

The study has been published in Physical Review Letters.