“I freeze high-frequency components to study how their behavior changes”
Electrical engineering at the limits of physics
For Nicole Zocher, the dual study program in electrical and information technology offered the perfect combination of hands-on experience and in-depth technical knowledge. Eager to delve deeper into the subject, she decided to pursue a Ph.D. and is now researching high-frequency circuits for superconducting quantum computers.
By Maria Poxleitner
The spring sun streams through the large windows of Nicole Zocher’s office. From the fifth floor, she and her colleagues overlook the expansive forest area bordering the Erlangen campus, all the way to the mountains and hills of Franconian Switzerland, as the low mountain range north of Nuremberg is called. Right next to this idyllic setting, the researchers at the Chair of High-Frequency Engineering at Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) are working on the technology of tomorrow. “I always start with a black box,” says Nicole. With “black boxes”, the 28-year-old doctoral student refers to various components of high-frequency circuits, such as resistors, transistors, or different printed circuit board (PCB) materials.
High-frequency (HF) technology involves generating, processing, and reliably transmitting signals with frequencies ranging from megahertz to gigahertz. This is achieved using HF printed circuit boards. These boards, often green in color, on which numerous elements such as copper traces, microchips, and a wide variety of electronic components form a complex circuit, are found in smartphones, Wi-Fi routers, and GPS systems, and all electronic devices that transmit HF signals. HF engineers are responsible for planning these complex circuits and designing HF printed circuit boards. They must ensure that all components are precisely matched so signals are transmitted correctly with minimal loss between components. To accomplish this, they must select the appropriate PCB material and know exactly what the specific properties of the individual resistors, capacitors, transistors, and other components are. “These are all commercially available components,” Nicole explains. While the manufacturers’ specifications outline their properties, the electrical engineer continues, these apply at room temperature. “Or perhaps down to -50°C, but below that ... no one has investigated it yet because no one has needed to.”
Nicole is investigating the use of these components in superconducting quantum computing. In this context, microwaves – which are also high-frequency signals – are used to control and manipulate the superconducting qubits, as well as to read out the results of calculations. Therefore, in a cryostat for superconducting quantum computing, HF printed circuit boards must be installed to process and transmit microwave signals. Depending on their location within the croystat, the PCBs operate at temperatures ranging from four Kelvin, or roughly -269°C, to a few millikelvin. “We're operating just above absolute zero,” says Nicole. “If I incorporate an inductor or a resistor into my circuit, each with a specific value at room temperature, what will happen when I cool the whole thing down to 50 millikelvin? Some pretty amazing things came out of that,” the doctoral student adds with a laugh. “To put it simply, I often say that I freeze high-frequency components to study how their behavior changes.“
Nicole Zocher, 28
Position
Ph.D. student
Institute
FAU – Chair for High-Frequency Engineering
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Degree
Electrical and information technology
Nicole is investigating how the properties of components used in high-frequency circuits change when they are cooled to temperatures near absolute zero. The models she derives from these investigations are necessary for designing microwave circuits that control, manipulate, and read out superconducting qubits.
From the engine plant to the cryostat lab
During her apprenticeship as an electronics technician specializing in automation technology at Siemens, she sometimes worked with electronics that were significantly larger than what she deals with today in her doctoral studies, Nicole says laughing, recalling her training placement at a motor plant in Nuremberg. It became clear very early on that she would pursue a career in a technical field, she continues, adding with a grin: “Even in elementary school, I had a multimeter to measure battery voltage.“ After graduating from high school, she chose to pursue a dual study program in electrical and information technology at the Nuremberg University of Applied Sciences.
“The dual study program is a great combination of hands-on work and theoretical studies,” says Nicole. As far as academic content is concerned, the bachelor‘s program is much more in-depth, she continues. On the other hand, the apprenticeship allows for more hands-on experience. “In the electronics technician apprenticeship, roughly speaking, you wire, solder, or build systems.” Nicole explains that she generally enjoys doing hands-on work in her free time. In addition to installing a solar panel system on the roof of her parent‘s house or carrying out minor and major renovations, this can also include working in the garden. Now that spring is here, she’s already gotten it back into shape.
Also from the very start of her doctoral studies, the young electrical engineer was able to jump right into hands-on tasks, because the cryostat laboratory, where she has conducted most of her research so far, had to be built and set up first. For example, she was responsible for selecting the appropriate measuring instruments and setting up and automating the measurement station, Nicole explains. She also helped select the cryostat equipment. However, the cryostat itself wasn’t delivered until two years later. “What was even more frustrating was that shortly after we put the cryostat into operation, the air conditioning in the lab broke down and we couldn't use the cryostat for a few months,” the doctoral student reports on her “run of bad luck with logistics.” She can laugh about it now, and at least she managed to carry out initial measurements and generate enough data for a first publication during the time between delivery and the air conditioning failure.
A second cryogenic laboratory is now being set up. The new cryostat is larger and can reach even lower temperatures than the one Nicole has been working with so far. Once again, she has been entrusted with setting up the lab. Beyond the hands-on work, however, it has always been the immersion in complex issues and the search for answers to unanswered questions that has driven Nicole. She has always wanted to get to the bottom of things, Nicole says. She was never satisfied with ready-made formulas. “When it came to figuring out how something was derived, I was the first one to tackle it. I’ve always wanted to know, ‘How did they come up with that?’” After completing her dual bachelor’s program and her master’s thesis – which she also completed in a company and which even resulted in a patent – she faced the decision of whether to stay in the development department or take a step further toward research. “The funny thing is, even back in my bachelor’s program, my colleagues at Siemens said, ‘If any of us is going to get a Ph.D., it’s going to be you’,” the doctoral student recalls with a laugh. And that’s exactly how it turned out. While searching for Ph.D. positions, she came across the Munich Quantum Valley position on the FAU website: “Building microwave circuits for a quantum computer – that sounded totally exciting.” Although she had heard about quantum computers in the media, she hadn’t encountered them in her studies until then. However, entering a new field through her doctoral studies – “that really motivated me.”
Innovative high-frequency technology for scalable quantum computers
The goal of her current research is to speed up the design process for microwave circuits used in quantum computers, Nicole explains. “I’m investigating how the HF properties of individual components or PCB materials change as we approach absolute zero, and then I model this behavior so I can provide these models to HF circuit designers.” In the long term, she hopes to use her findings to develop a pulsed amplifier, the electrical engineer continues. The processor of a superconducting quantum computer, on which the individual qubits are located, is typically placed at the bottom of the cryostat. That is where it is coldest. The qubit signals are routed upward through the cryostat’s various cooling stages via long cables, finally reaching the measuring instruments located outside the cryostat. Currently, amplifiers are typically installed in the upper chamber of the cryostat, meaning they operate at a temperature of four Kelvin, Nicole explains. The goal is to develop an amplifier circuit that functions at even colder temperatures, allowing it to be placed closer to the processor. “We want to amplify these extremely weak signals as quickly as possible so they won't be severely disrupted by thermal noise, which occurs at higher temperature levels, as they travel through the long cables in the readout path.” Additionally, the future amplifier is designed to operate in pulsed mode, unlike current amplifiers, which run continuously. This means it will only be switched on when a signal is being read out. “This reduces heat input, which allows us to pack more qubits and readout paths into the cryostats.” Thus, Nicole adds, her work also contributes to scaling superconducting quantum computers.
However, before designing a microwave circuit for such a pulsed amplifier, one must first determine how the PCB material and necessary components, such as capacitors, resistors, and transistors, behave when cooled to increasingly lower temperatures, Nicole summarizes her central task once again. The mere technical possibility of approaching absolute zero to within a few millikelvins and to further and further cooling down her HF components and circuits fascinates the doctoral student. “I’m not doing traditional high-frequency circuit design; instead, I’m operating the components at the limits of physics.”
Published 30 April 2026; Interview 24 March 2026