Paradigm shift in cryptography: UP23@it-sa winner Quantum Optics Jena

Quantum communication replaces mathematical processes with quantum mechanical ones. This opens up completely new possibilities and could revolutionise cryptography. Quantum Optics Jena is leading the way. The start-up won the pitch for the Startup Award UP23@it-sa at the it-sa Expo&Congress.

A start-up from Jena wants to revolutionise cryptography. For encrypted communication, until now, both parties have to agree on a key. Quantum communication aims to make this superfluous. German start-up Quantum Optics Jena has developed a method for this. Demand is high. Co-founder and CEO Kevin Füchsel explains why.

• The secure exchange of keys is one of the problems that has not yet been solved satisfactorily.
• Quantum communication enables the automated exchange of keys.
• Incidentally, this type of communication is very secure against eavesdropping, as any interference is immediately noticeable.

How did you go from science to founding a company?

I initially studied physics and did my doctorate in photovoltaics at the Fraunhofer Institute for Applied Optics and Precision Engineering (Fraunhofer-Institut für Angewandte Optik und Feinmechanik, Jena, Germany). That had nothing to do with quantum technology. During my doctorate, I designed a photovoltaics start-up, but didn't actually realise it. Instead, I was able to continue working at Fraunhofer after my doctorate. This work later led to a new start-up with colleagues from there. It was clear from the start that it would be about quantum communication. Quantum communication is different from quantum computing, which is often lumped together. That's how Quantum Optics Jena was born in 2020. From my role at Fraunhofer, I became Managing Director and CEO, responsible for strategic positioning and customer business. This includes market analyses and many discussions with customers so that we know their requirements and can implement them.

How has Quantum Optics developed so far and what is the idea behind your start-up?

Right from the start, we had the vision that we wanted to apply the laws of quantum physics to achieve a new level of information security. This resulted in a complete quantum key distribution system. We were able to convince investors quickly after the company was founded. Shortly afterwards, we started developing entangled photon sources. But this alone is not enough to build a scalable company, because very few customers can do anything with it. We quickly realised that we had to offer a complete system for which customers did not need any knowledge of quantum physics. Today, we are working on this with 20 employees.

What is a quantum key distribution system?

We generate photons, i.e. light particles that are quantum-physically entangled. In mathematical terms, entanglement means that the states of these particles, for example the colours, cannot be considered individually. In this example, it is only when you measure them that you know what colour they are. For example, they are either blue or green when they are sent out. When I measure them, the colour turns blue and I know that the other side is also blue. So you always know what is seen on the other side without talking to the other side, but only at the moment you measure it.

Translated into computer science, this means that a key is generated by many colour measurements and you immediately have the key on the other side without communicating directly with the side about the measurement. Here, ones and zeros are no longer defined by maths, but by quantum mechanical chance.

To what extent does this process increase IT security?

The transmission of these light particles is secure in the sense that the particles change immediately if someone "touches" a particle while travelling, for example by measuring it. Any attempted interference or interaction with this connection is immediately visible. This makes it possible to recognise eavesdropping at the moment of eavesdropping. In our case, quantum bit errors would then occur immediately and be recognised. This could trigger an alarm.

This enables us to automatically distribute symmetric keys that are used to encrypt information. What happens in the process is completely transparent to the expert observer and is not based on mathematical assumptions. This heralds a paradigm shift for cryptography. But that also makes it difficult, because now physicists are coming along and saying to computer scientists: why don't you just use physics instead of maths and let that guarantee information security? Of course, not everyone likes that.

How has the response to your development been so far?

We are generally meeting with great interest. Many organisations are currently looking at our development and evaluating it. For example, BWI, which operates the communications networks for the German Armed Forces. There is also interest in the telecommunications sector, for example from companies implementing 5G and 6G mobile communications standards. We currently have very full order books.

What do you produce and market? What does your hardware look like?

Our products are devices that can be installed in server racks, for example. They are networked with servers. A server receives a key from our device and uses it to encrypt the data, which is then transmitted via a fibre optic cable connected to our device. On the receiver side, there is another device that measures the signals on the fibre optic cable and can then generate the key from them without an explicit key exchange having taken place.

Now, you have won first prize at the ATHENE Startup Award UP23@it-sa for this?

That's right; we are delighted with the award and the recognition it brings. We were able to impress with our product, its applicability and the corresponding growth curve of our company. Our forecast is also very promising. This subsequently resulted in interesting customer and investor enquiries. However, we are also pleased that the topic of quantum is thus gaining more relevance and visibility.

What are your plans for the near future?

We are focussing on further product development, as our product is constantly evolving and new features are always being added. Another topic in the near future is certifiability, for example by the BSI (Note: German Federal Office for Information Security). This is a prerequisite for use in an official environment. We are also currently changing the production process so that the devices can be assembled automatically. This is a necessity in order to produce larger quantities.

We have now set up a site in the United States and are considering how we can expand it. In this field, the US are exceptionally behind Europe. We see good opportunities to win customers there. At the moment, we are the only manufacturer to offer multi-party quantum keys. We would like to maintain this position.

Interview: Uwe Sievers