Photonic chip that isolates light could end size limitations in quantum computing and devices

Researchers at the University of Illinois used readily available materials to create a small photonic circuit that uses sound waves to isolate and control light and can adapt to different wavelengths. The innovation could lead to miniaturized quantum devices that transform quantum computing and information systems.

Transmitting data by manipulating photons -- particles of light -- that travel at the speed of light using quantum devices is how information reaches around the globe almost instantly. The new breakthrough makes quantum technology more functional and portable. The researchers, funded in part by the U.S. National Science Foundation, published a paper detailing their results in Nature Photonics.

Using common optical materials, the team developed a non-magnetic isolator that is a fraction of the size of conventional isolators. The chip-sized isolator can isolate and control the direction of light and eliminate the adverse impact of unblocked light on device performance. The design is an answer to the scale and utility issues of conventional quantum technology, the scientists said.

"An isolator is a device that allows light to pass uninterrupted one way and blocks it completely in the opposite direction,” said study author Benjamin Sohn. “This unidirectionality cannot be achieved using common dielectric materials or glasses, so we needed to be a little more innovative.”

Added principal investigator Guarav Bahl, "Atoms are the perfect references anywhere in nature and provide a basis for many quantum applications. The lasers we use to control atoms need isolators that block undesirable reflections. We wanted to design a device that naturally avoids loss, and the best way to do that is to have light propagate through nothing. The simplest bit of 'nothing' that can still guide photons along a controlled path is a waveguide, which is a component in a photonic circuit."

Miniaturizing quantum computing devices is critical to realizing the full potential of quantum technology, the researchers said. Developing quantum technology devices with applications that are scalable and practical will advance quantum computing, information systems and applications.