New Breakthrough in Optical Circuit Programming: Light Computing With Hair-thin Fibers

Recently, scientists at Heriot-Watt University (UK) have discovered a powerful new method for programming optical circuits.
This method may play a crucial role in realizing future technologies such as unbreakable communication networks and ultrafast quantum computers. The research has now been published in the journal Nature Physics.
Mehul Malik, an experimental physicist and professor of physics at the School of Engineering and Physical Sciences at Heriot-Watt University in the United Kingdom, explains, "Light can carry a huge amount of information, and optical circuits, which compute with light rather than electricity, are seen as the next big leap in computing technology."
"But as optical circuits become larger and more complex, they are increasingly difficult to control and fabricate - which can affect their performance. Our research demonstrates another, more general approach to designing optical circuits, using naturally occurring processes."
Professor Mehul Malik and his team conducted their research using commercial optical fibers. Widely used around the world to transmit the Internet to individual homes and businesses, this type of fiber is thinner than the width of a human hair and uses light to transmit data.
By taking advantage of the natural scattering behavior of light in optical fibers, they found that the optical circuits within the fibers could be programmed in a very precise way.
"When light enters an optical fiber, it scatters and mixes in complex ways. By understanding this complex process and precisely shaping the light that enters the fiber, we've found a way to craft circuits of light amidst this chaos."
Optical circuits are critical to the future of quantum technologies, which are designed at the microscopic level by working with individual atoms or photons (light particles). These technologies include powerful quantum computers with huge processing power and quantum communication networks that cannot be hacked.
Prof. Mehul Malik explains, "For example, optical circuits are needed at the end of quantum communication networks so that information can be measured after traveling long distances. They are also a key part of quantum computers for performing complex calculations on light particles."
Quantum computers promise significant advances in areas such as drug development, climate prediction and space exploration. Machine learning - artificial intelligence - is another area where optical circuits are used to process large amounts of data quickly.
Prof. Mehul Malik points out that the power of light lies in its multidimensionality: "We can encode a lot of information on a single particle of light. Its spatial structure, its temporal structure, its color. If you can compute all these properties at the same time, you can unleash tremendous processing power."
The researchers also showed how their programmable optical circuits can be used to manipulate quantum entanglement. This is a phenomenon in which two or more quantum particles, such as photons, remain connected even when they are far apart. Entanglement plays an important role in many quantum technologies, such as error correction within quantum computers and implementing the most secure types of quantum encryption.
Prof. Mehul Malik and his research group at Heriot-Watt University's Beyond Binary Quantum Information Laboratory conducted the study with collaborating scholars from institutions such as Lund University in Sweden, Sapienza University of Rome in Italy, and the University of Twente in the Netherlands.
The research was funded by QuantERA, a leading European network of 39 public research funding organizations (rfo) from 31 countries, including the Austrian Research Promotion Agency (FFG) - Austria's national funding agency for industrial research and development; and the European Research Council (ERC) - the EU's funding organization for cutting-edge research.