A group from DESY Photon Science created a source of squeezed laser light on a component the size of a microchip. It is based on a tiny ring with a nanoscale structure that serves as a resonator. The team's development contributes to the industrialization of technologies such as tap-proof quantum internet or superfast quantum computers. Laser light usually displays the same degree of quantum blurring in its amplitude and phase. However, sophisticated laboratory techniques can be used to reduce the uncertainty in one of the two variables, such as the phase. Squeezing the light in this way increases the achievable accuracy of measurements. Although this automatically increases the uncertainty in the other variable, in this case, the amplitude, this fact is not relevant for applications that depend on the phase of the oscillation. Such states of light are already used in gravitational-wave detectors, where they substantially increase the sensitivity of the measuring systems, which are several kilometers in diameter. The DESY Photon Science team has now discovered a new and simple way of generating squeezed light on a photonic, silicon-based chip, with a quality previously unattainable in such systems. At 7.8 dB, the squeezed light produced is close to the threshold of around 10 dB that is necessary for many quantum applications. This microphotonic component is a crucial step towards the realization of the quantum internet. Courtesy of DESY. A large part of this development was a microscopic light ring, also known as a microresonator, with a diameter of just 150 μm. Laser light is fed into the microresonator, thus producing squeezed states using systematic non-linear effects. Using simulations and a specially developed correction method to allow for manufacturing inaccuracies, the team was able to further optimize the structure. “We have given the inner walls of the resonator a nanoscale corrugation pattern,” said researcher Alexander Ulanov. “This suppresses unwanted light processes which would otherwise compromise the squeezing of the light.” The chip was manufactured using a commercial semiconductor process, which will accelerate scalability. To make the design compatible, with traditional processes, the researchers deliberately distorted the pattern so that the inevitable blurring during the manufacturing process would lead to the desired result. The light states that are produced using the technology are key for various quantum applications, including quantum computers and the quantum internet. And, the low-loss silicon-nitride platform used can, in principle, be combined with other components, such as integrated lasers or detectors. The team is currently working on increasing the squeezing level to more than 10 dB, which is considered the threshold for many quantum computing protocols. This research was published in Nature (www.doi.org/10.1038/s41467-025-66703-x).