Modern computers are not unlike the looms of the industrial revolution: They follow programmed instructions to weave intricate patterns. With a loom, you see the result in a cloth or carpet. With a computer, you see it on an electronic display.
Now a group of physicists and computer scientists who are funded by Microsoft are trying to take the analogy of interwoven threads to what some believe will be the next great leap in computing, so-called quantum computing.
If they are right, their research could lead to the design of computers that are far more powerful than today’s supercomputers and could solve problems in fields as diverse as chemistry, material science, artificial intelligence and code-breaking.
They met here this weekend to explore an approach to quantum computing that is based on “braiding” exotic particles known as anyons — what physicists describe as “quasiparticles” that exist in just two dimensions rather than three — in order to form the building blocks of a supercomputer that exploits the weird physical properties of subatomic particles.
The proposed Microsoft computer is mind-bending even by the standards of the mostly hypothetical world of quantum computing.
Conventional computing is based on a bit that can be either a 1 or a 0, representing a single value in a computation. But quantum computing is based on qubits, which simultaneously represent both zero and one values. If they are placed in an “entangled” state — physically separated but acting as though they are connected — with many other qubits, they can represent a vast number of values simultaneously.
And the existing limitations of computing power are thrown out of the window.
In the approach that Microsoft is pursuing, which is described as “topological quantum computing”, precisely controlling the motions of pairs of subatomic particles as they wind around one another would manipulate entangled quantum bits. Although the process of braiding particles takes place at subatomic scales, it is evocative of the motions of a weaver overlapping threads to create a pattern.
By weaving the particles around one another, topological quantum computers would generate imaginary threads whose knots and twists would create a powerful computing system. Most important, the mathematics of their motions would correct errors that have so far proved to be the most daunting challenge facing quantum computer designers.
First proposed by the physicist Richard Feynman in 1982, quantum computing has mostly been of interest to academics, the National Security Agency and the Pentagon’s Defense