At Fraunhofer IZM, quantum physics is being brought out of the textbooks and into the real world. With optical glass-integrated waveguides, a universal platform is being created that enables solutions for tap-proof quantum communication and high-precision quantum sensors - miniaturized, fast and customer-specific.
At Fraunhofer IZM, quantum physics is being brought out of the textbooks and into reality. With optical glass-integrated waveguides, a universal platform is being created that enables solutions for tap-proof quantum communication and high-precision quantum sensors - miniaturized, fast and customized.
Schrödinger's cat is in a box. Is it alive or dead? While the box is closed, the pet can be in either state. If you end the experiment and open the box, a state is determined. What at first glance appears to be a philosophical paradox actually describes a basic principle of quantum theory, superposition. It is one of the many special features of quanta that form the basis of many physical laws.
Quantum technologies have been part of our everyday lives for over half a century. The classic laser and the atomic clock, for example, are first-generation quantum technology devices. Researchers are now entering a new era: they can not only read out the states of individual quanta, but also actively excite and even manipulate them. This second quantum revolution opens up completely new applications in communication, simulation, computing and sensor technology. However, quite complicated and energy-intensive laboratory setups are currently still needed to measure or calculate with the so-called qubits.
Researchers at the Fraunhofer Institute for Reliability and Microintegration (IZM) have therefore set themselves the task of taking the step from basic university research to industrial and commercializable applications. In order to realize cost-effective devices, they rely on technical solutions from telecommunications. There, photons, i.e. particles of light, are the carriers of quantum mechanical information. Protocols and infrastructures in the form of special printed circuit boards are already available for their transmission and manipulation.
The researchers see a great opportunity for solutions in quantum communication in the use of optical waveguides integrated into glass. The clear advantage of glass fibers over semiconductors is that glass is transparent to near-infrared waves, which are used in quantum technologies. In addition, glass as an optical waveguide has significantly lower losses, ensures less residual scattering of light, is cheaper to produce and can be recycled.
Secure communication with quantum cryptography
The use of these glass-based chips in conjunction with quantum photonics makes it possible to realize tap-proof communication channels, which are indispensable in the banking sector, for public security and for the requirement of sovereign data protection.
The crux of quantum photonic encryption lies in the fact that the state of a photon inevitably changes after it has been read out. This makes it possible for the recipient to recognize whether the information has been intercepted, read out or reproduced along the way. Recognizing this interception in the communication channel and thus preventing data leaks and hacker attacks is not possible with conventional electronic encryption methods.
Quantum sensors for unprecedented measurement accuracy
In quantum sensor technology, experts make use of the fact that qubits can overlap like waves. The resulting quantum mechanical phase reacts extremely sensitively, which means that even individual atoms can be measured. This results in sensors for gravitational and magnetic fields, for example, which achieve unprecedented accuracy compared to conventional sensors. This solution also enables measurements to be taken at an absolute level, which means that sensors do not need to be calibrated.
To ensure that the high-precision sensors are not disturbed by undesirable environmental influences, the researchers are developing insulating vacuum chambers on glass so that the quantum sensors can also be used outside laboratories.
Dr. Wojciech Lewoczko-Adamczyk and Oliver Kirsch, research associates at Fraunhofer IZM, know the advantages of quantum sensor technology: "The vacuum chambers on glass make it possible to use quantum mechanical sensors in places where they were previously unthinkable, for example as biosensors. By measuring individual atoms whose spectra react to magnetic fields, light can be used to gain insights into the magnetic fields of the heart or brain, complementing medical imaging with CT or MRI." The researchers are trying to miniaturize the sensor systems to such an extent that patients can even move freely during the examination. "Quantum sensors can also make a contribution to food research and medical technology, as even extremely low concentrations of viruses or bacteria in a solution can be measured far beyond conventional standards," continues Oliver Kirsch.
However, the researchers' vision is greater than just the development of individual products: the aim is to create a universal platform that enables quantum photonic devices to be built quickly and in line with customer requirements. To achieve this, waveguides just a few micrometres in width are integrated into a glass substrate, which guide the light specifically to where the quanta can be excited and read out. In addition, the glass substrate is metallized with structures in order to also transmit electrical signals. This creates a platform that combines optical and electrical information at quantum level - an electro-optical circuit board. To get closer to this goal, the researchers in the Quantum Photonic Packaging group have optimized their photonic technologies to such an extent that they are suitable for use in the quantum range. In several projects, they want to advance quantum technologies at Fraunhofer IZM through to industrial production.
