“It connects two different worlds”
Research at the interface between physics and computer science
While Laura Herzog's bachelor's thesis focused on philosophical questions concerning the interpretation of quantum mechanics, her current research as a doctoral student is in the field of quantum computing. What she particularly likes about her Ph.D. topic in quantum error correction is that it allows her to combine her knowledge as a theoretical physicist with practical problems from computer science.
By Maria Poxleitner
“Zsssh...clack” – Laura Herzog's colleagues have grown accustomed to the slight sound that can be heard every morning in the large shared office when the doctoral student opens her can of “Spezi” soda. While others start their workday with coffee, Laura starts hers with the mixed drink of cola and orange soda. She got into the habit sometime during her bachelor's studies, admits the 26-year-old. Her desk is located at the very back of the “TUM Quantum Space”, as her team has dubbed the bright, loft-like room at the top floor of the Technical University of Munich (TUM) building on Arcisstraße. Laura puts her Spezi soda on a crocheted coaster that she made herself. “That's a surface code!” she says, pointing to the crocheted square made up of two red and two yellow squares arranged in a checkerboard pattern, with a semicircle, also red or yellow, attached to each side along half the length.
The doctoral student is pursuing her Ph.D. in the field of quantum error correction, in which a quantum error correction code specifies how a so-called logical qubit is encoded in several physical qubits. There are many different quantum error correction codes. The surface code is one of them, and the two-color pattern with squares and semicircles is its graphical representation – in a sense, the building instructions for the logical qubit. “There is a physical qubit at each corner of these squares,” Laura explains. In the case of her coaster, there are exactly nine physical qubits, she adds. “And the colored shapes, the squares and semicircles, represent the stabilizers of the code,” the doctoral student continues. These stabilizers are used to continuously monitor for errors, whereby the qubits located at the corners of a shape are monitored, and the color of the shape indicates the type of error to look out for. “The stabilizers describe what you have to measure continuously in order to detect and then correct your errors.” However, it is not the data qubits located at the corners that are measured – as this would change their quantum state – but rather auxiliary qubits located between the data qubits. All together, that is the entire coaster, so to speak, is also referred to as a “patch”, Laura concludes.
Understanding the details in order to abstract
Data qubits, auxiliary qubits, stabilizers – the small coaster, the patch, contains a great deal of information, and the simple pattern of squares and semicircles hides more complexity than meets the eye. In her current research, Laura is attempting to detach herself from all these details, abstracting them to derive more general approaches for compiling quantum algorithms. As with classical computers, compiling means translating an algorithm into a language that the processor understands and ultimately implementing it as a sequence of physical operations that can be executed on the respective hardware platform.
Laura Herzog, 26
Position
Ph.D. student
Institute
TUM – Chair for Design Automation
QACI
Degree
Physics
Laura is researching compilation methods for error-corrected quantum computers. For that, she first has to study the details of specific quantum error correction codes. Then, she has to abstract from these details to derive more general computer science problems.
In quantum hardware with error correction, the quantum error correction code used also plays a role at a certain point in this complex compilation process. “The surface code is currently the most popular code in the community. Everyone always uses surface code. But other codes also have their advantages,” Laura emphasizes. In one of her first papers, she therefore examined how much she could move away from the details of specific codes and derive a more general formalism for certain compilation steps that is valid not only for the surface code, but for several different codes at once. To do this, she first had to understand how the various quantum error correction codes work in detail – a topic that, as the doctoral student notes, involves many fundamental concepts of quantum information theory and is very physics-heavy. However, based on this detailed knowledge, she continues, one can try to abstract and formulate problems that ultimately stem from computer science. It is precisely this bridge-building that Laura likes so much about quantum error correction: “That's what I think is so nice about the topic. It, in a sense, connects two different worlds.”
This is also reflected in Laura's working group. “It's very interdisciplinary. I’d say about half of us studied physics, and the other half studied computer science.” Laura herself belongs to the group of physicists. She completed her bachelor's degree at Ludwig-Maximilians-Universität München (LMU). The doctoral student recalls knowing early on that she wanted to study physics. At the age of 13 or 14, she began reading popular science books on physics. “I was fascinated by it all and decided then and there that I wanted to understand it and study it.” She read about different topics: “About cosmology, astrophysics, quantum mechanics… I don't think I really understood at the time that you don't learn all of this when you study physics, but that you have to decide on one area at some point,” she says with a laugh.
From the philosophy of quantum mechanics to quantum computers
Laura decided to focus on quantum sciences. However, she did not gravitate toward quantum computing from the outset. “In my bachelor's thesis, I focused more on the philosophy of quantum mechanics,” she explains. The thesis dealt with understanding Bell's inequality and involved an in-depth examination of concepts such as “realism” and “locality.” After earning her bachelor's degree, Laura moved away from these very fundamental questions about the interpretation of quantum mechanics, and, with the “Quantum Science and Technology (QST)” master's program offered jointly by LMU and TUM, took a more application-oriented approach to quantum mechanics. She was part of the second cohort of this brand-new program and one of the first students to receive the MQV Fellowship for Women. “The fellowship was a huge relief,” the physicist emphasizes. And there are still significantly more men than women enrolled in the QST master's program, Laura adds. “I think it's good that the scholarship is specifically for women!”
Although quantum computing was covered in the compulsory lectures during her master's program, Laura says, she herself increasingly “drifted into condensed matter” – an area of physics that primarily deals with the properties of solid and liquid systems, which are determined by the interaction of a large number of particles. She ultimately wrote her master's thesis at the Chair of Theoretical Nanophysics. What appealed to her most about the topic of her thesis was the methodology: in a lecture on numerical methods in condensed matter physics, she realized how much she enjoyed writing scientific code. This was confirmed once again during her master's thesis.
Her enjoyment of programming and the feeling that writing software was what she wanted to do in the future were also reinforced during Laura's position as a research assistant at the Fraunhofer Institute for Integrated Circuits IIS in Nuremberg, where she was already employed in the months before starting her master's thesis. Initially, she had no intention of continuing the job at Fraunhofer while working on her master's thesis, but she enjoyed the work so much that she decided to stay on. “I don't like to think back on the stress I felt back then. I like to think back on everything I learned – and I would actually say that working at Fraunhofer brought me back to quantum computing.” Unlike her current doctoral thesis topic, her work there focused on methods to run large algorithms on today's NISQ computers, that is non-error-corrected quantum computers. It was through this position that the physicist's attention was brought to the work of her current doctoral supervisor, Robert Wille, with whom her colleagues at Fraunhofer had collaborated on a project.
Online abroad
Laura owes her decision to apply for the position at Fraunhofer, which ultimately led her to her current doctoral position, to a somewhat botched semester abroad. She was just looking for a position as research assistant to bridge the gap between the end of the semester and the start of her master's thesis, which had arisen due to the different semester dates in China and Germany, the physicist explains. However, Laura never actually went to China. Due to the COVID-19 pandemic, she was only able to take the semester abroad online, she continues with a laugh. Nevertheless, she has no regrets. Not only is the semester abroad the reason she came to Fraunhofer and, through that, to her current doctoral position, but the additional semester also allowed her to take additional lectures that she would have otherwise never had time for. “For example, a lecture on machine learning,” says Laura. “Or one on Wittgenstein,” she adds with a smile. All in all, however, it was a “strange time”, she says, because the lectures took place in the middle of the night: “I often went to bed early, then got up at two in the morning, stayed awake until five, and then slept for another three hours – that was wild.”
Meanwhile, the doctoral student values having a more consistent daily routine. Separating work and leisure time is also important to her, something she had consciously decided before she began her doctorate. In her free time, Laura is currently working on what she calls a “major private project.” Her great-grandfather was in the resistance during the Nazi regime, she explains. “For a long time, this was just like a legend in my family, but a year ago, I started researching it more closely.” Her most important discovery so far is her great-grandfather's Gestapo file, which she found in and requested from the Federal Archives. This kind of research gives you a different perspective on that period, says Laura. “It makes it much more accessible, not just something in history books.” It makes you more aware that it was all real, she adds, “a reality that is still relevant today.”
“Working in an interdisciplinary team is very enriching. You can learn a lot from each other.”
Currently, Laura comes to the office every day, even though they are very flexible about where they work from. Many of her colleagues are also on site. There is a focused atmosphere. One can see, that the team enjoys working here and feels comfortable in its “Quantum Space“. The room is decorated with many plants, especially colorful Lego flowers. The young physicist is very happy with her choice of doctoral position: “Working in an interdisciplinary team is very enriching. You can learn a lot from each other.” She herself benefits, for example, from the high standards upheld here at the chair in terms of “writing good code”. “I enjoyed writing code before, but always did it in a ‘physicist’ way.” The work here at the chair is in a completely different league, she adds. Learning all these rules and quality standards for good software development is an important goal for Laura in her doctoral studies. And as for what comes next – “we'll see.“
Published 28 November 2025; Interview 15 October 2025