Experimental quantum computing for students

A maximum of 18 students and doctoral candidates were able to take part in the practical course this semester – but demand was significantly higher. Together with the lecturers, they implemented three experiments in the field of quantum computing and six more on the topic of quantum optics on the Fraunhofer quantum computer.

But how do the operations on the first commercial quantum computer, which is run by IBM at the site in Ehningen, Baden-Württemberg (Germany), actually work? “The quantum computers are managed remotely via a cloud using the Python programming language,” Eilenberger explains. “For this purpose, we have provided the course participants with interactive lab books in which quantum physical and algorithmic aspects are presented. In addition, the books discuss the basics of programming the quantum computer.” Subsequently, participants were encouraged to program the quantum computers themselves within these interactive digital notebooks. Furthermore, they were to learn to read out and make sense of the results. “In the process, we solved problems in the area of simulating quantum optical systems as well as on what is known as Grover's algorithm,” Eilenberger further discusses.

Grover's algorithm, also known as “quantum search algorithm”, can find solutions to unstructured problems much faster than classical computers. The team of faculty, doctoral candidates and students first solved the following problem: a + b = 17. That is, the participants found numbers for a and b whose sum equals 17. “Of course, this is merely a toy problem,” clarifies Eilenberger. “We were able to show a real quantum advantage, by contrast, in the simulation problem. We could show that entangled qubits, i.e., photons, allow significantly more precise interferometric measurements than classical photons.” This method is not only suitable for improving optical metrology, but also for building more precise clocks, the quantum researcher explains. “Using the QSystemOne, we were able to demonstrate a real quantum advantage for up to eight entangled qubits!”

"With this course, Fraunhofer IOF and the University of Jena as well as their partners have entered new didactic territory,” concludes AP co-director Prof. Andreas Tünnermann. “At the same time, however, we are also demonstrating that site-specific cooperation between the participating institutions provides important impetus for local educational excellence.” In addition to the Abbe Center of Photonics, the university center of the University of Jena with a focus on optics and photonics, and Fraunhofer IOF, the Leibniz Institute for Photonic Technologies e.V. were also involved in the implementation of the course.

The lab course was very well received by both the participants and the lecturers. The instructors praised the students' great motivation to tackle even complex problems and excellent results in the process. “The students really got stuck in,” is how Dr. Falk Eilenberger sums up the students’ commitment. The offer is to be repeated in coming semesters due to the high demand.

“Experimental quantum technologies should become an integral part of quantum education here in Jena in the future," Andreas Tünnermann hopes. “We also want to digitize numerous experiments from this practical course in order to improve the international perception of the location as a hotbed of excellence in quantum technologies.”

IBM QSystemOne is the world's first family of circuit-based commercial quantum computers. It was unveiled by IBM in early 2019. The Fraunhofer-Gesellschaft has had exclusive access to one of the quantum computers, which is operated at the Ehningen site in Baden-Württemberg, Germany, since January 2021.

Access for doctoral candidates and students was made possible as part of the “Quantum Now” funding program, an initiative of the Fraunhofer-Gesellschaft. Employees of the institute as well as (PhD) students as potential young researchers are to be given the opportunity through this program to address current problems in the fields of optics and photonics, while at the same time familiarizing themselves with the potentials of quantum technologies. Further experiments in the field of quantum optics have been made possible through the “digiPhoton” and “qp-tech.edu” initiatives, funded by the German Federal Ministry of Education and Research through the Center of Excellence in Photonics.