Tap-proof quantum communications are nearer

Tap-proof quantum communications are nearer

Technology News |
By Ally Winning

Science is currently facing a new era of quantum technology: because they are now not only able to read the states of individual quanta, but also to actively excite and even manipulate them, completely new applications are opening up in communication, simulation, computing and sensor technology. However, very complicated and space-consuming laboratory set-ups are still needed at present to solve meaningful tasks with the so-called Q-bits.

Researchers at the Fraunhofer Institute for Reliability and Microintegration IZM (Berlin) have therefore set themselves the task of taking the step from basic research to industrial and commercial applications. In order to realise cost-effective devices, they are relying on technical solutions from the field of telecommunications. There are photons, the carriers of quantum mechanical information. Protocols and infrastructures for their transmission and manipulation already exist in the form of special circuit boards.

The researchers see a great opportunity for solutions in quantum communication in the use of optical waveguides integrated in glass. The clear advantage of glass fibres 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 more cost-effective in production and can be recycled.

The use of such glass-based circuits in conjunction with quantum photonics makes it possible to realise tap-proof communication channels, as is indispensable in banking, for public security and for the demand for 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. It is therefore possible for the receiving party to recognise whether the information has been intercepted, read out or reproduced on its way. To detect this interception in the communication channel and thus prevent data leaks and hacker attacks is not possible with classical electronic encryption methods.

In quantum sensor technology, experts are taking advantage of the fact that Q-bits can overlap like waves. The resulting quantum mechanical phase reacts extremely sensitively, so that even individual atoms can be measured. In this way, sensors for gravitational and magnetic fields, for example, are created that achieve a previously unattained level of accuracy compared with classic sensors. In addition, this solution enables measurements to be made 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 of laboratories.

Dr. Wojciech Lewoczko-Adamczyk and Oliver Kirsch, research assistants at Fraunhofer IZM, explain the advantages of quantum sensor technology: “The vacuum chambers on glass make it possible to use quantum mechanical sensors in places where it was 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, which can supplement medical technology images with CT or MRI”. The researchers are trying to miniaturise 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, since even with extremely low concentrations of viruses or bacteria in a solution, measurements can be made far beyond the conventional standards,” Kirsch continues.

However, the researchers’ vision goes beyond the development of individual products: they want to develop a universal platform that makes it possible to build quantum photonic devices quickly and in accordance with customer requirements. Towards this end, waveguides of a few micrometres in diameter are integrated into a glass substrate to guide the light directly to where the quanta can be excited and read out. In addition, the glass substrate is metallized with structures to transmit electrical signals. This creates a platform that combines optical and electrical information at quantum level – the electro-optical equivalent of the familiar circuit boards used in electronics.

To get closer to this goal, the researchers of the Quantum Photonic Packaging group have optimised their technologies to the point where they are suitable for quantum applications. In doing so, they have opened up a view to the industrial production of quantum optical systems. In several projects they now want to achieve the industrialisation of these systems. 

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