Photonic Chips – replacing Electronic Chips

An Another Major Break Through In the Field of Computing,Scientists Have Developed A Chip That Could Change The Face of Computing Paving The Way For a New Generation of powerful Qunatum Computers.


A Team of International Researchers Has Developed A Revolutionary Optical Chip ,That Operates on The Principles of Light Rather Than Electricity.With integrated circuits that use light instead of electricity, photonic chips will allow for faster computers and less data loss when connected to the global fiber-optic network.


This Major Innovation Could Lead To "Quantum Computers"  Capable of Complex Processing And Stimulations That Are impossible For Today's Computers.


 “We want to take everything on an electronic chip and reproduce it on a photonic chip,” says Liang Feng, a postdoctoral scholar in electrical engineering and the lead author on a paper to be published in the August 5 issue of the journal Science. Feng is part of Caltech’s nanofabrication group, led by Axel Scherer, Bernard A. Neches Professor of Electrical Engineering, Applied Physics, and Physics, and co-director of the Kavli Nanoscience Institute at Caltech.



In that paper, the researchers describe a new technique to isolate light signals on a silicon chip, solving a longstanding problem in engineering photonic chips.
An isolated light signal can only travel in one direction. If light weren’t isolated, signals sent and received between different components on a photonic circuit could interfere with one another, causing the chip to become unstable. In an electrical circuit, a device called a diode isolates electrical signals by allowing current to travel in one direction but not the other. The goal, then, is to create the photonic analog of a diode, a device called an optical isolator. “This is something scientists have been pursuing for 20 years,” Feng says.
Normally, a light beam has exactly the same properties when it moves forward as when it’s reflected backward. “If you can see me, then I can see you,” he says. In order to isolate light, its properties need to somehow change when going in the opposite direction. An optical isolator can then block light that has these changed properties, which allows light signals to travel only in one direction between devices on a chip.





We want to build something where you can see me, but I can’t see you,” Feng explains. “That means there’s no signal from your side to me. The device on my side is isolated; it won’t be affected by my surroundings, so the functionality of my device will be stable.”
To isolate light, Feng and his colleagues designed a new type of optical waveguide, a 0.8-micron-wide silicon device that channels light. The waveguide allows light to go in one direction but changes the mode of the light when it travels in the opposite direction.
A light wave’s mode corresponds to the pattern of the electromagnetic field lines that make up the wave. In the researchers’ new waveguide, the light travels in a symmetric mode in one direction, but changes to an asymmetric mode in the other. Because different light modes can’t interact with one another, the two beams of light thus pass through each other.

Previously, there were two main ways to achieve this kind of optical isolation. The first way — developed almost a century ago — is to use a magnetic field. The magnetic field changes the polarization of light — the orientation of the light’s electric-field lines — when it travels in the opposite direction, so that the light going one way can’t interfere with the light going the other way. “The problem is, you can’t put a large magnetic field next to a computer,” Feng says. “It’s not healthy.

The second conventional method requires so-called nonlinear optical materials, which change light’s frequency rather than its polarization. This technique was developed about 50 years ago, but is problematic because silicon, the material that’s the basis for the integrated circuit, is a linear material. If computers were to use optical isolators made out of nonlinear materials, silicon would have to be replaced, which would require revamping all of computer technology. But with their new silicon waveguides, the researchers have become the first to isolate light with a linear material.


Although this work is just a proof-of-principle experiment, the researchers are already building an optical isolator that can be integrated onto a silicon chip. An optical isolator is essential for building the integrated, nanoscale photonic devices and components that will enable future integrated information systems on a chip. Current, state-of-the-art photonic chips operate at 10 gigabits per second (Gbps) — hundreds of times the data-transfer rates of today’s personal computers — with the next generation expected to soon hit 40 Gbps. But without built-in optical isolators, those chips are much simpler than their electronic counterparts and are not yet ready for the market. Optical isolators like those based on the researchers’ designs will therefore be crucial for commercially viable photonic chips.




courtesy:sciencedaily.com

DNA computer ‘calculates square roots’

Computing Have Taken A New Shape .A New Era of Computing is made To Set out With the Advent Of Dna Computers As Scientists Design  a New digital circuit designed to use molecules to crunch a Solve variety of complex math problems.
Sounds A Bit Strange But Next Generation of computing Is Possible With DNA.As Scientists Realise The Fact That Millions of natural supercomputers exist inside living organisms, including your body. DNA (deoxyribonucleic acid) molecules, the material our genes are made of, have the potential to perform calculations many times faster than the world's most powerful human-built computers. DNA might one day be integrated into a computer chip to create a so-called biochip that will push computers even faster.

DNA computing uses chemical reactions to solve problems in which a number of DNA strands act as "bits".

The work, reported in Science, required 130 strands of DNA to work in a cascade of programmed chemical changes.

The approach is not designed to rival traditional electronics, but rather to allow computing to occur in biological contexts, perhaps even in the body.

DNA computing was first proposed by Leonard Adelman in 1994, to solve what is known as the "travelling salesman problem" - determining the shortest path that joins a number of geographically separated locations.

Since then, a wide array of approaches has aimed to make use of the properties that make DNA attractive for computing: it can be made to order and its interactions with itself are well-studied and reliable.

In 2006, Erik Winfree of the California Institute of Technology (Caltech) and his colleagues published an article in Science a framework making use of one of these approaches, known as strand displacement.

Stretches of DNA made of just one strand (rather than the two joined strands that form the well-known double helix) were used as anchor points for other single strands.

By carefully "programming" the movement of these strands, the researchers were able to recreate a number of elements familiar from conventional computing, including logic gates, amplification, and feedback.

"Those circuits were smaller [than those of the current work], but more importantly, they were built using more complex DNA molecules that made systems more difficult to debug and had other problems," Professor Winfree told BBC News.

Stranded

Now, Professor Winfree and his collaborator Lulu Qian have employed a scheme using what they call "seesaw gates", which accomplish the shuffling and exchange of DNA strands using simpler machinery.

The work showed that seesaw gates could again be used to create logic gates - the basis of electronic computing's manipulation of information - and represented a five-fold leap in the number of DNA sections ever implemented in such a DNA computer.

The approach can be scaled up in complexity far further, the authors suggest - but the process is slow.

For example, it was used to calculate the square root of a four-bit number, but the process took between six and 10 hours.

However, Professor Winfree said that contrary to conventional electronics, the goal is not just high speeds.

"We are no longer pursuing the goal targeted by Len Adleman's original DNA computing experiment: to compete with silicon by using the massive parallelism of chemistry to solve combinatorial problems in mathematics," he explained.

"Instead, our goal is now - and has been for many years - to enrich chemistry itself so that molecular behaviours can be programmed.

"We'd like to make chemical systems that can probe their molecular environments, process chemical signals, make decisions, and take actions at the chemical level."

Binyamin Gil, a member of the research group that in 2009 published on a DNA computer that could "answer" logical conundrums, told BBC News that the DNA computer of the new work exhibited more "digital behaviour" than other molecular computing approaches and thus that "it may be more robust, reliable and scalable".

"The complexity of the presented work - together with the potential of scalability and of interfacing it with other molecular computers - make this paper important and interesting," he said.


Source :BBC