PQ-NEXT Core with René Zander, Fraunhofer FOKUS

What drives PQ-NEXT from within? PQ-NEXT Core reveals the minds and teams behind the project. By showcasing the perspectives, insights, and ambitions of those leading its key areas, we uncover the vision and collaboration that shape PQ-NEXT’s vision.

Let’s start by getting to know René Zander from Fraunhofer FOKUS a little better and by introducing the team that will work on the project.

My name is René Zander, and I’m a quantum computing scientist at Fraunhofer FOKUS, where I have been working for almost three years. Prior to that, I completed my Master’s and PhD in mathematics at TU Berlin, specialising in dynamical systems and discrete integral systems.

At Fraunhofer FOKUS, I work across a range of quantum computing topics, including quantum algorithms research, quantum benchmarking, and post-quantum cryptography. I am also a developer of the high-level programming language Eclipse QRISP, which we have been developing over several years and continue to develop through the PQ-NEXT project and several other European and German-funded projects.

My mathematical background is directly relevant to this work, cryptography mechanisms at their core rely on mathematics. RSA cryptography relies on the hardness of factorising numbers into prime factors, while post-quantum cryptography relies on different mathematical problems, such as finding shortest vectors in lattices. When it comes to testing the security of PQC algorithms and developing quantum algorithms that could attack them, a strong mathematical foundation is essential.

On this project, I am mainly working alongside my colleague Tobias Köppel, who is also a mathematician with a background in differential equations. Together, we use our knowledge in mathematics and programming to contribute to PQ-NEXT, specifically within Work Package 3 “Post-Quantum Cryptanalysis Enablers”.

What motivated you to join this EU-wide consortium?

It is a great opportunity to work with partners from across Europe, get to know different institutions, countries, and people through European projects, and share knowledge and gain different perspectives. Some consortium partners are more focused on use cases, while we come from a more theoretical side. That mix of expertise is valuable.

It is also an opportunity to find new collaborators for Eclipse CRISP, which is an open-source quantum programming language. We have already had contributions from colleagues at AGH in Kraków, and working within a European consortium like this opens further doors for collaboration.

“It is also an opportunity to find new collaborators for Eclipse CRISP, which is an open-source quantum programming language.”

What problem does your role in the project address in simple terms, and why is it critical for the project’s implementation?

The core problem we address is that post-quantum cryptography methods are relatively new and therefore less tested than established cryptography, such as RSA or elliptic curve cryptography. During the NIST standardisation process, which took place over several years, some proposed algorithms that were believed to be secure against quantum attacks turned out not to be secure, even against classical attacks in some cases.

Our work, therefore, enables researchers to use quantum computers to implement and test attacks against these new post-quantum cryptography mechanisms. The goal is to increase our confidence in the security of these algorithms before they are widely deployed.

“Our work, therefore, enables researchers to use quantum computers to implement and test attacks against these new post-quantum cryptography mechanisms.”

What are the main activities, tasks, and objectives of your work? And how is your work connected to other tasks and activities?

Work Package 3, titled Post-Quantum Cryptanalysis Enablers, aims to enable testing of PQC algorithms against quantum attackers. It is divided into three tasks:

1. Quantum Software Stack Development — We will further develop the Eclipse CRISP library to ensure seamless compilation of large-scale quantum attacks. This involves ensuring that all relevant algorithms for attacking post-quantum cryptography are fully compatible with our JAX-based compilation pipeline. To address scalability limitations of Python-based quantum programming, we use an intermediate representation approach with MLIR-based compiler technology.

2. Quantum Algorithm Research — This task focuses on researching quantum algorithms that could be used to attack post-quantum cryptography. We will look at optimisation algorithms such as the Quantum Approximate Optimisation Algorithm (QAOA), linear system solvers, and other quantum algorithms, and investigate how they could be applied to quantum cryptanalysis.

3. Post-Quantum Programming Suite — The third task involves implementing and testing a post-quantum programming suite. This tool, built on top of the Eclipse CRISP library, will allow researchers to easily test different PQC mechanisms against quantum attacks, providing a suite of cryptographic primitives paired with a suite of quantum attackers.

In terms of connections to the wider project, Work Package 3 is closely related to Work Packages 2, PQ-NEXT Migration Modelling Tools, and Work Package 4, Large Scale Pilot Demonstrators. Work Package 2 identifies which PQC algorithms are relevant and should be used; the inventory of cryptographic primitives it produces feeds directly into our testing work in Work Package 3. Our findings can then serve as a basis for Work Package 2 and inform Work Package 4 on which algorithms should be used in practical applications. We collaborate particularly with Indra, the University of Athens, and AGH Kraków within this work package.

Moving on, a personal note. What is the main outcome you personally hope this project will achieve?

Any new insights into the security of PQC algorithms or the identification of vulnerabilities would be a great outcome. Of course, the primary goal of the work package is to deliver the post-quantum programming suite that enables benchmarking of PQC algorithms and seeing that tool used in practice would be a very meaningful result.

“Any new insights into the security of PQC algorithms or the identification of vulnerabilities would be a great outcome.”

Looking ahead, what excites you most about the post-quantum era?

The exciting part is really the challenge of transitioning to post-quantum cryptography before fault-tolerant quantum computers capable of breaking traditional RSA or elliptic curve cryptography become a reality. As a mathematician, I am also genuinely excited to work on the underlying mathematical problems and investigate them further.

It is worth noting that post-quantum cryptography itself does not offer new utility; it simply replaces existing cryptographic methods with ones that will be safe against quantum attacks. The real excitement lies in ensuring this transition happens in due time.

More broadly, quantum computing is a fascinating field because of its many potential applications in areas such as quantum chemistry and quantum physics research.