Physics
Bachelor of Science (B. Sc.)

Elementary particle physics investigates the basic building blocks of matter and the fundamental interactions between these building blocks and thus forms the basis for our understanding of the world, starting with the Big Bang. The knowledge gained in this process is theoretically summarized in the Standard Model (SM) of particle physics. With the discovery of the Higg particle in 2012 at the CERN research center in Geneva through the ATLAS and CMS experiments, the SM can be considered complete.

Although the SM can precisely predict thousands of observables and these predictions are confirmed by many experiments, this theory is still only seen as an approximation of an even more fundamental theory(BSM = beyond SM), which is now being intensively searched for. The reason for this view is that the SM cannot answer elementary questions, such as the existence of ordinary matter in the universe, and also leaves open the existence of dark matter.

The main goal of current research in particle physics is to find evidence for the BSM theory. This can be done either by directly searching for new, heavy particles at the Large Hadron Collider (LHC) at CERN or by comparing ultra-precise measurements - e.g. at CERN - with precise calculations within the framework of the SM. Any significant deviations of these measurements from the corresponding SM calculations can then provide clues to the structures of the BSM theory. The activities in Siegen in this field are divided as follows:

• Experimental particle and astroparticle physics
  Siegen physicists are significantly involved in the ATLAS experiment at CERN and are investigating in particular the heaviest known elementary particle, the top quark. The Siegen physicists are also involved in the Pierre Auger experiment in Argentina, with which extremely energetic cosmic rays can be measured with a 3,000 km² detector field.
  
• Theoretical particle physics
  Theoreticians at the University of Siegen produce calculations with the highest precision in the world as part of the SM and study the properties of hypothetical BSM models. Both analytical methods (from paper and pencil to computer algebra) and numerical simulations are carried out on computer clusters in Siegen or worldwide.
  

Solid-state physics is probably the broadest field of physics and includes topics such as semiconductor physics and electronics, magnetism, nanostructures, crystallography, low-temperature physics and polymer physics. This field is very complex, exciting and full of profound ideas. It ranges from very application-oriented research to highly abstract theories. With the help of solid state physics, we can understand a large part of the world around us. It is therefore also very relevant for applications, some of which have strongly shaped our world and our society in the past. This is particularly obvious for microelectronics, which has given rise to computers and smartphones, and which is built entirely on semiconductor physics. At the same time, it is also a field full of fundamental discoveries; no fewer than 50 Nobel Prizes have been awarded for discoveries in the field of solid-state physics. Solid-state physics systems can often serve as laboratories on the nanoscale to experimentally investigate problems in quantum physics or statistical physics.

The three Siegen working groups Experimental Nanophysics, X-ray Physics and X-ray Tomography use a wide range of modern investigation methods. These range from the diffraction of ultra-short X-ray pulses using free-electron lasers to X-ray fluorescence tomography and scanning tunneling microscopy, which can image solid surfaces at atomic resolution. Very different systems are examined: We determine stresses and defect densities in materials used in vehicle construction and analyze the manufacturing process of composite materials. The analysis of secondary radiation caused by X-rays allows the chemical composition of samples to be determined, which is particularly relevant for biomedical samples. Here we investigate atherosclerotic plaques in order to prevent heart attacks in the future and analyze the distribution of nanoparticles in cancer cells. We observe the dynamics of soft matter, e.g. proteins during phase transitions. The high time resolution of our methods allows us to observe ultrafast processes in magnetic systems. The strong laser pulses used in this process in turn trigger changes in the matter on the nanoscale, which we investigate. We are investigating new ultrathin (two-dimensional) materials based on the prototypical graphene (Nobel Prize in Physics 2010), which consists of a monoatomic layer of carbon. It is assumed that these materials can significantly advance the miniaturization of electronic circuits.

In recent decades, quantum optics has developed into an innovative and interdisciplinary field of research in physics. Two developments have taken place: Firstly, it is now experimentally possible to trap, control and manipulate individual atoms, ions or photons. This allows experiments to be carried out that were previously purely thought experiments. On the other hand, new concepts for quantum information processing are being researched in the interplay between quantum physics and information theory. Examples include quantum cryptography, which makes it possible to encrypt messages in a provably secure manner, and the quantum computer, which can be used to solve important problems faster than classical computers. In Siegen, three research groups are working in the field of quantum optics and quantum information:

In the Experimental Quantum Optics working group, individual atoms are captured and cooled to near absolute zero using laser light. This makes it possible to observe the internal dynamics of atoms and their movement, both of which are determined by the laws of quantum mechanics. Through the targeted preparation of individual atoms or atomic crystals, experiments on a variety of physical phenomena are possible, in particular for the investigation of fundamental questions, e.g. concerning the measurement process in quantum mechanics. The group is currently working intensively on the realization of a quantum computer in which individual, simply ionized atoms serve as the elementary switching unit: The bits of classical information processing are replaced by quantum bits.

The Theoretical Quantum Optics working group investigates theoretical questions of quantum mechanics. Much of this work concerns the phenomenon of entanglement: according to the rules of quantum mechanics, two or more particles can be in a state in which they can only be understood as a complete system, which can lead to paradoxical effects that Albert Einstein once described as "spooky action at a distance". This raises many questions for researchers: How can entanglement be characterized theoretically? How can it be demonstrated in experiments? What can entanglement be used for? These topics are dealt with mathematically on the one hand, but on the other hand, discussions are also held with experimental physicists in order to analyze their experiments.

The Laboratory for Nano-Optics includes both experimental and theoretical research activities. The group investigates light and its interaction with matter at the nanoscale. The group is particularly interested in studying individual quantum systems and investigating quantum phenomena that occur in the sub-wavelength range. These findings can lead to the development of devices such as new types of light sources, sensors and functional materials. One example of the research topics is the investigation of novel quantum systems that emit individual photons in a highly controlled manner by coupling them to optical resonators.

• Examination regulations (FPO-B) for the subject Physics (PHY) dated 16.08.2023 (valid from winter semester 2022/23)
• Second regulation amending the subject examination regulations (FPO-B) for the subject Physics (PHY) dated 16.09.2024
• Examination regulations for the Bachelor's degree course in Physics dated 01.08.2018 (valid until 30.09.2026)

• Framework Examination Regulations (RPO-B) for the Bachelor's degree program at the University of Siegen dated 01.08.2018
• Second regulation amending the framework examination regulations (RPO-B) for the Bachelor's degree program
  at the University of Siegen dated 24.06.2022
• Third regulation amending the framework examination regulations (RPO-B) for the Bachelor's degree program
  at the University of Siegen dated 25.07.2023
• Fourth regulation amending the framework examination regulations (RPO-B) for the Bachelor's degree program
  at the University of Siegen dated 12.06.2025

• Examination regulations for the Bachelor's degree program in Physics dated 17.01.2013 (valid until 31.03.2022)
• Handbook of module elements for the Bachelor's degree program in Physics dated 18.09.2019 (valid until 31.03.2022)
• Examination regulations for the Bachelor's degree program in Physics dated 08.04.2010 (valid until 31.03.2017)
• Module handbook for the Bachelor's degree course in Physics dated 28.06.2012 (valid until 31.03.2017)