How test & measurement and network encryption enable new quantum technology applications

Billions are being invested in quantum technologies by the public and private sectors. Quantum milestones reported on by the media follow in quick succession. Visionary applications in sensor technology, computing and communications appear to be within reach. High-precision test & measurement (T&M) solutions from Rohde & Schwarz enable science, industry and public institutions to perform specific tests on individual quantum systems. And the company's encryption experts are bringing quantum based secure communications out of the labs for use in relevant applications.

Quantum computing, quantum sensor technology and quantum communications – all three technologies have disruptive potential. The amounts of money alone speak volumes about the innovation potential ascribed to quantum technologies. In addition to global commitments of well-known venture capital funds, billions in public resources are also being funneled into national and transnational research funds.

The German Federal Ministry of Education and Research, for example, has set up a 2.6-billion-euro quantum tech fund. The EU Quantum Flagship initiative has a budget of at least 1 billion euros, and the US National Quantum Initiative Act has 2 billion US dollars at its disposal.

Quantum effects have become part of our everyday lives. Modern smartphones, for example, contain several hundreds of billions of transistors, predominantly in flash memory chips. Their function – controlling currents and voltages – is based on the quantum mechanical properties of semiconductors. The first generation takes advantage of natural quantum effects. By contrast, the second generation of quantum technology is based on creating and controlling individual quantum states.

Fast. Faster. Quantum computing.

Our world is controlled by binary code. Conventional computers process data as sequences of ones and zeroes, true or false, off or on. This applies to everything, from simple text processing to virtual reality in the metaverse. But the world we live and work in is becoming increasingly complex. The amount of data we need to process is growing rapidly. The annual volume of data generated digitally increased tenfold between 2012 and 2020, and is now expected to triple again by 2025. The predicted amount of data is more than 180 zettabytes – or in more familiar terms, 180 trillion gigabytes.

For this reason, conventional computers face two insurmountable obstacles: time and complexity. The larger the volume of data, the more time you need to process that data sequentially. The more complex the problem, the lower the probability that binary code, with only two states, will be able to efficiently calculate a solution. Quantum computers have the potential to overcome both obstacles thanks to insights from modern physics.

Hand in hand instead of either-or

Like conventional bits, quantum bits (qubits) form quantum mechanical memory units. In addition to just zeros and ones, they can also assume overlapping, mixed states. This simultaneity represents a fundamental technological paradigm shift. We can now run conventional sequential calculation methods simultaneously, which is why a quantum computer can save so much time.

But above all, the new quantum mechanical approach allows us to process new and much more complex questions. However, it’s not an either-or decision, either conventional processing power or quantum computing. Instead, what matters is integrating existing and quantum systems depending on the task.

Physics versus logic

In the quantum world, a particle can be in two places at the same time. Only when it is observed can you narrow down its location, for example by measuring it. In other words, it has no definitive location until it is observed. This unusual property is also why it is extremely unstable. Instead of using individual physical qubits, which can be very error-prone, multiple qubits are grouped into a logical qubit. However, the challenge here is that you need quantum systems with as many as one million logical qubits in order to answer practical questions, like protein folding. A logical qubit can contain up to 100 physical qubits, but the highest processing capacity is currently only 127 physical qubits.

Zurich Instruments is the youngest member of the Rohde & Schwarz family. The T&M market for quantum computing, in particular, holds enormous potential for both companies. Operating and maintaining quantum computers requires a wide range of specific T&M solutions, because RF signals need to be generated and measured with extremely high precision in order to effectively create and record quantum states. Control systems for quantum computers are part of the company’s portfolio.

Secure. More secure. Quantum communications

Quantum computers have the potential to push the limits of processing efficiency. But this brings challenges, including secure communications. Pandora's box began opening in the early 1990s, with the onset of the first algorithms that could break conventional crypto algorithms using high-performance quantum computers.

Alternative encryption methods have since come to the fore. There are essentially two main approaches. The first is post-quantum cryptography, which involves entirely conventional encryption methods with one key difference: they can survive attacks from quantum computers unscathed. The algorithms used in this approach are based on theoretical assumptions for which no effective attacks are currently known using either quantum or conventional computers.

The other approach relates to quantum key distribution (QKD). The German Federal Office for Information Security (BSI) and the National Institute of Standards and Technology (NIST) are two of the main drivers of innovation in this area. In an increasingly digitalized world, private-sector customers, and government customers in particular, are dependent on trustworthy IT security solutions. Secure communications networks have become critical infrastructure in advanced information societies.

These innovative solutions are shifting the focus of cryptology. Conventional methods, as well as more recent post-quantum methods, are based on mathematical assumptions, i.e. the idea that certain tasks cannot be calculated with sufficient efficiency. Quantum key distribution, by contrast, is based on physical principles.

The first QKD devices were primarily developed by physics working groups, and commercialization work has been ongoing for several years. Rohde & Schwarz Cybersecurity is providing and leveraging its extensive expertise in security solutions, as well as its experience in building and implementing secure devices and systems, in numerous research projects.

Innovation through collaboration

Aside from actually developing the technology, interacting with customers and participating in research groups and industry associations is also important. Rohde & Schwarz has therefore been part of many emerging networks from the very beginning. Here are just a few: