Research Labworks for MSc
The Research Labwork in Physics in the 1. and 2. master semester serves the purpose of training in a specific physical issue as well as project planning in order to improve experimental skills.
One project should be completed during the semester at one afternoon per week (4 CP). The experiments can be chosen from one of the following topics: optics, solid state physics, astronomy, computational physics, and material science. Depending on the specific conditions, one project can be done by either on or more students, in the latter case, with complementary tasks.
Students who would like to take the Research Labwork in the winter semester 24/25 please register immediately with the advanced lab course office or in Friedolin. The registration for the respective projects in the moodle list in this winter semester will start Friday, September 27th, 2024 at 10 am.
At the end of the summer semester students submit (at the very latest on 26.01.2025) their results in form of a scientific poster. The presentation of the poster will be on February 05th, at the FPraktikum (attendance is mandatory)
The Organization of the research labwork is managed by the FPraktikum office. For choosing a project, please contact us via physik.fpraktikum@unijena.de. Please do not send requests individually to project supervisors.
The list of topics is at the moment only valid for the current semester (summer semster 2024) and will only be updated three weeks before the start of the new semester, once the new selection of topics has been confirmed (we will send an Email, when this is the case  so please register at friedolin)!!!

Advanced Experimental Microscopy  SuperResolution Microscopy
Seeing is believing. This sentence is as true as it is tricky. Most cellular components and processes, crucial for the nuanced understanding of (human) life, are not observable by conventional light microscopy since Abbe’s Law describes their maximum resolution to roughly half the wavelength of the observed light. This law is literally set in stone in Jena. However, over the past 15 years several ways of cleverly circumventing this diffraction limit were developed and implemented, achieving threedimensional resolutions down to the nanometer range, resulting in the evergrowing field of optical superresolution microscopy, for which the 2014 Nobel Prize in Chemistry was awarded.
The aim of this projects is to introduce, understand and apply the principles of state of the art fluorescence microscopy techniques, used e.g. in a broad range of modern biomedical and cellbiological research. Students prepare their own, fluorescently labeled, biological samples and will image them on a variety of advanced microscopes with different (resolution) capabilities. The qualitative and quantitative comparison of acquired images will illustrate the advantages and limitations of the respective microscopy technique.
Goals and Context
 Principles and application of advanced fluorescence microscopy techniques
 Concept of diffractionlimited and superresolution
 Preparation of fluorescently labeled, biological samples
 3D & multicolour imaging at the nanoscale
Methods
 Cell culture and wet lab
 Fluorescent labeling
 A selection of advanced fluorescence microscopy techniques from the IAOB toolbox:
 Confocal Laser Scanning Microscopy
 Array Scan Microscopy
 Stimulated Emission Depletion (STED)
 Structured Illumination Microscopy (SIM)
 SingleMolecule Localization Microscopy (SMLM)
 MINFLUX Nanoscopy
 Image analysis by Fiji/ImageJ
Prerequisites
 An open mind and motivation for independent thinking
 Students should be able to explain the general difference between confocal and widefield microscopy and have basic knowledge on the concepts of superresolution microscopy (e.g. Abbe’s diffraction limit)
 You should know the basic principles of fluorescence
A good preparation for the course is the biophysics lecture from Prof. C. Eggeling
Person in charge: Christian Franke & Katharina Reglinski
Supervisors: Christian Franke & Katharina Reglinski
Venue: Microscopy Labs of the IOAB in the ZAF and Abbeanum or at the IPHT (Beutenberg)
The topic is suitable for two groups with 12 students each.

Advanced techniques for stabilization of optical cavities
Advanced measurement techniques and stable optical systems are crucial for scientific research
breakthroughs in fields like quantum optics, spectroscopy, and fundamental physics. These
techniques enable precise probing of matter and light properties, as well as detection of phenomena like gravitational waves. At the core are stabilization methods for optical cavities and lasers. Optical cavities enhance lightmatter interactions for highprecision measurements. Cavity stabilization ensures reliability and precise control over photon generation and manipulation. The presentation will cover general principles and techniques for stabilizing optical systems, beyond specific applications. It will explore advanced stabilization methods like SideofFringe (SOF) locking and PoundDreverHall (PDH) locking, which have wide applicability in diverse scientific settings.Teaching Goals and Content
 Understand the principles and importance of optical cavities in current technologies.
 Design and construction of an optical cavity.
 Calculations of the modematching optics of a cavity by using ABCD matrix.
 Explore the SideofFringe (SOF) locking technique for cavity stabilization.
 Explore the PoundDreverHall (PDH) locking technique for stabilizing optical cavities by using radiofrequency techniques.
 Compare and contrast the SOF and PDH locking techniques in terms of performance and applicability.
 Analyze the stability and reliability of the optical cavity using these locking techniques.
Experimental Techniques and Equipment
 Optical alignment of optical cavities.
 Continuous wave pump lasers at suitable wavelengths.
 Photodetectors for monitoring the cavity's reflected and transmitted light.
 Electrooptic modulators for phase modulation in the PDH technique.
 Lockin amplifiers for demodulation and proportionalintegral (PID systems) for feedback control.
 Data acquisition systems for recording and analyzing the locking signals.
Contact:
Place: Fraunhofer IOF institute
Supervision: MSc. L. Gonzalez
For this experiment two students are recommended.

Femtosecond Laser
Nowadays the generation of ultrashort laser pulses with a duration down to some femto seconds is state of the art. Such pulses find their application not only in the field of scientific research to investigate ultrafast processes, to perform ultraprecise spectroscopy, or to generate extreme electrical and magnetic fields through ultrahigh light intensities, but they are also applied in material processing, medicine, especially in ophthalmology. Nevertheless, the generation and metrology of ultrashort pulses require complex measurement techniques. The basics to understand the underlying effects of pulse generation, stretching and compression as well as their measurement will be taught here. Some of these effects are based on nonlinear optics and frequency conversion, that requires phase matching to get reasonable efficiencies. Second harmonic generation and twophoton absorption are used for pulse characterization by autocorrelation here. The limitations of the autocorrelation for the reconstruction of the temporal behavior of the laser field will be investigated in more detail.
Teaching goals and content
 Working principle and properties of solidstate lasers (Ti:sapphire)
 Cavity stability and longitudinal cavity modes
 Dependence of output power on pump power
 Generation of femtosecond pulses by Kerrlens modelocking
 Compensation of group velocity dispersion in optical cavities
 Impact of spectral phase on pulse duration and temporal pulse shape
 Measurement of bandwidth and duration of laser pulses
 Application of FourierTransform to explain pulse stretching and compression
 Interferometric and intensity autocorrelation and their limitations for pulse characterization
 Measurement of group velocity dispersion (GVD) of several materials
Experimental techniques and equipment
 diodepumped, frequencydoubled 5W Nd:YV0_{4}laser as pump source
 homemade Ti:sapphire femtosecond laser with prism GVD compensation
 external prism pulse compressor
 optical spectrometer
 second harmonic generating autocorrelator
 photodiodes, powermeter and oscilloscope
Contact:
Supervisor: Dr. Joachim Hein
Place: FPraktikum
For this experiment two students are recommended.

Imaging without imaging: using algorithms to replace optics
In modern optical imaging, precise methods for investigating micro and nanoscale structures are of great importance. Diffraction imaging revolutionizes optical imaging by foregoing traditional optics and instead relying on computer algorithms to create highresolution images. Despite its potential, there are significant challenges in reconstructing images from diffraction patterns.
The main focus of this project is to investigate the optical diffraction imaging in the visible range. The various influences such as the size of the illumination spot, the coherence, the structure size, the monochromaticity or bandwidth and the overlap with other beams in the visible spectral range will be taken into account. A particular focus will be on exploring the convergence of reconstruction algorithms as a function of the above parameters. In particular, multicolor diffraction still raises many fundamental questions.
Teaching Goals and Content
 Design and construction of an optical test setup
 Basics of diffraction imaging and ptychography
 Influence of various light sources on imaging
 Development and application of reconstruction algorithms
 Experimental applications and diagnostic methods
Prerequisites
 Basics in optics, Fourier optics, and image processing
 Interest in modern imaging and algorithm development
 Experimental skill and problemsolving ability
 Basic knowledge in programming, ideally in Python or Matlab
Contact:
Supervisor: Dr. Martin Wünsche and Dr. Jan Rothhardt
Place: MaxWienPlatz 1 and AlbertEinsteinStr. 6
The topic is suitable for two groups with 2 students each.

Spatial characterization of laser beams from ultra short pulsed lasers
Spatial laser beam characterization plays a critical role in ultrashort pulsed laser material processing, where precision and control are essential for achieving desired outcomes. The primary importance of spatial beam characterization lies in its ability to provide accurate data about the energy distribution, fluence, and intensity profile of the laser beam. These parameters are crucial in determining how the laser interacts with the material, influencing the quality, efficiency, and reproducibility of the process. In material processing, such as micromachining or surface structuring, understanding the spatial energy distribution helps identify inconsistencies that can lead to defects or poor quality results. Similarly, in nonlinear optics, where processes like harmonic generation and multiphoton absorption are highly intensitydependent, spatial beam characterization reveals how localized intensity affects the efficiency of these effects.
The goal of this project is to build and characterize an automated setup to record and analyze the spatial properties of beams from ultrashort pulsed laser systems. In addition, different laser sources and beam shaping systems should be characterized.
Teaching goals and content
 Fundamentals and methods for laser beam characterization
 Basics of spatial beam shaping
 Alignment and characterization of optical setups
 Development and automation of measurement procedures
 Image processing and data analysis
Prerequisites
 Basic knowledge in optics
 Good experimental skills
 Programming with Python, Matlab or LabView
Contact:
Supervisor: Hagen Kohl
Place: Institute of Applied Physics (IAP, Beutenberg)
The topic is suitable for one or two students.

Ultrafast lattice dynamics in semiconductors excited by strong laser fields
Interaction of intense ultrashort laser pulses with crystalline solids might excite a coherent vibrational motion in the lattice having ultrafast time scale – from several tenses to several hundreds of femtoseconds. The physical mechanism of the excitation is typically the Raman excitation, when nuclear motion is triggered by the electron polarization driven by intense laser pulses, whereas the type of the excited vibrational modes depends on relative orientation of the laser polarization in respect to the symmetry axes of the crystal.
The goal of the suggested project is the experimental investigation of timedependent dynamics of lattice vibrations in a very novel magnetic semiconductor layered material CrSBr excited by intense, ultrashort laser pulses. The experiments are based on a pumpprobe technique when an intense, ultrashort laser pulse excites vibrational motion of the lattice via the resonant stimulated Raman scattering, and the corresponding phonon dynamics is probed by a weak pilot ultrashort pulse. Specifically, a novel detection scheme will be used, that is based on the dynamically changing birefringence, induced in the material due to the lattice motion. This detection scheme involves a boxcar integrator and lockin amplifier detection to achieve a very high sensitivity. The spectrum and the temporal evolution of the coherent phonons will be measured as a function of crystal orientation and the intensity of the pump laser pulses.
Prerequisites
 Basics knowledge in optics
 Good experimental skills
 LabView as highly desirable skill
Contact:
Supervisor: Dr. Daniil Kartashov
Place: Institute of Optics and Quantum Electronics (IOQ, MaxWienPlatz 1)
The topic is suitable for one or two students.

Ultrafast fiber laser oscillators
Ultrashort pulse lasers are nowadays one of the most interesting types of lasers, since they have opened up new applications in the scientific, medical and industrial fields. In fact, achieving ultrashort pulses (<1ps) is a unique ability of lasers that separate them from other light sources. Usually such ultrashort pulses, which are some of the shortest events ever created by Mankind, are obtained using the technique of mode locking, which has become one of the most important methods in modern lasers.
Additionally, among all available laser architectures, fiber lasers have stablished themselves as one of the most attractive types of lasers due to their simplicity, efficiency, lowcost, maintenancefree nature, compactness, robustness and highpower scalability. In fact, fiber lasers are currently replacing more traditional types of lasers in many applications.
In this project, you will get to know fiber lasers by building and characterizing a modelocked fiber laser able to deliver several 100 fs pulses. In this project you will build the cavity, try out different configurations and learn about the physics of mode locking. At the end, you will have created from scratch one of the most appealing types of lasers: an ultrafast fiber laser.
Teaching Goals and Content
 Understand the principles of modelocking and fiber lasers.
 Design and construct a fiber cavity.
 Use of SemiconductorSaturable Absorber Mirrors (SESAMs) to achieve modelocking.
 Learn to characterize an ultrafast laser.
 Analyze the performance of the laser as different parameters of the cavity are changed.
 Perform simulations of the laser.
Experimental Techniques and Equipment
 Handling of optical fibers (stripping, cleaving, splicing, etc).
 Coupling of optical radiation in/out of a fiber.
 Use of SESAMs.
 Systematic characterization of the laser performance using, e.g. power meters, spectrometers, etc.
Contact:
Supervisor: Cesar Jauregui & Jan Rothhardt
Place: Institute of Applied Physics/Abbe center of Photonics
This experiment can be carried out by one of two students.

Electron Diffraction of twodimensional films of antimony
According to de Broglie matter has not only particle but also wave character. It was shown that electrons, due to their rest mass, already exhibit wavelengths of around 1 angstrom at acceleration voltages of about 150 V, which is in the range of atomic distances in solids. Crystals therefore represent natural diffraction gratings for accelerated electrons, just as they do for Xrays of similar wavelengths. However, due to the strong inelastic interaction between electrons and atoms, the inelastic mean free path of electrons in solids ranges from less than 1 to several 100 nm which is thus considerably smaller than for Xrays. This makes electron diffraction especially suited for the investigation of crystalline surfaces and thin layers.
The aim of this projects is to understand principles of electron diffraction, especially reflection high energy electron diffraction (RHEED) and lowenergy electron diffraction (LEED), which are a widely used characterization method for inorganic compounds with the ability of in situ growth monitoring of thin films. Students prepare their own samples, starting from cleaning singlecrystal surfaces, followed by the deposition of films via molecular beam epitaxy as well as their structural characterization by means of RHEED and LEED. All preparation and analyzing steps are performed under ultrahigh vacuum (UHV) conditions.
Goals and context
 principles and application of electron diffraction in two dimensions (2D)
 concept of reciprocal space
 preparation of atomically clean single crystals and two dimensional materials
 highlyordered ultrathin layers by molecular beam epitaxy
 vacuum technology (pumps, gauges, rest gas analysis etc.)
Methods
 UHV chambers with:
 RHEED device (electron gun, phosphor screen, camera)
 MCPLEED (electron gun, phosphor screen, micro channel plates, camera)
 sputter gun and sample heater
 vacuum pumps (roughing, turbo, ion getter, and titanium pump)
 metal single crystals as sample substrates
 effusion cells for deposition
Contact:
Supervisor: Dr. Felix Otto
Venue: Labs of AG Fritz (ZAF)
The topic is suitable for two students.

Growth and Characterization of Carbon Nanotubes
Hardly any other topic inspires the intellectual curiosity in the past decades such as nanotechnology. In addition to the enormous range of applications in the semiconductor, textile and automobile industry, mechanical engineering, architecture, aerospace engineering, medical and energy technology, it also provides an interesting insight into the physical and chemical processes and properties at the atomic and subatomic level. In this field the socalled carbon nanotubes are of particular importance. Since their discovery in 1991 by Sumio Ijima and his research group as well as the experimental studies of Bethune et al., different research groups largely succeeded to understand the production mechanism of these nanoscopic structures and their wide potential for applications. Beside to their high tensile strength and elasticity they have extraordinarily good conduction properties. In research they are therefore used as electronic components such as field effect transistors and electrical sensors and as probes for scanning force and scanning tunneling microscopes. In the industry they are used, among others, as conducting composites.
In this project, CNTs are grown by means of the chemical vapor deposition (CVD) technique. First, the substrates needed shall be prepared by the student itself and, especially, the for the CVD process required catalyst (cobalt or iron) shall be grown structured by means of the thermal deposition method. The characterization of the substrates and CNTs shall be done by means of atomic force microscopy (AFM) and Auger electron spectroscopy (AES) as well as scanning electron microscopy (SEM) and Raman spectroscopy, respectively. The letter is a widelyused optical analysis tool, which is perfectly suited to gain information about the quality of the CNTs as well as their structures to a certain extent. After optimizing the process parameters of the CVD, selfmade CNT networks shall be tested in terms of their performance as gas sensors (FET setup). For this purpose, IV curves are measured computeraided in dependence of different environmental parameters (partial pressure of the gas to be detected, temperature, …).
Objectives
 Nanotechnology / Nanostructures
 Carbon nanotubes  structure, properties, preparation, growth, use, characterization
 Coating processes (in particular chemical and physical gasphase deposition)
 Sample preparation
 Vacuum technology
 Learn about chemical vapor deposition (CVD) systems
 Using the scanning electron microscope (STM) or atomic force microscope (AFM)
 Application of Raman spectroscopy
 Electrical characterization: IU, sensor properties
Experimental techniques
 CVD equipment, medium vacuum
 Samples: single crystalline silicon with oxidic passivation and quartz with catalyst coating of both substrates
 Vacuum coating, thermal evaporation
 Raman spectrometer
 Scanning electron microscope (SEM)
 Atomic Force Microscope (AFM)
 Auger electron spectrometer (AES)
 Computeraided measurements of IV curves
Contact:
Supervisor: Dr. Marco Grünewald
Venue: FPraktikum and labs of the IFK
The topic is suitable for one or two students.

Insitu Flux Measurement in a Broad Ion Source
Ion sources are applied in a wide range of processes for e.g. doping, quantum dot fabrication and the creation of buried layers. For theses purposes, broad beam ion sources can be utilized to maintain fast processing times even on large implantation areas.
In 2022, operation of a unique fourgrid accelerator broad ion source (4GABIS) started at the IAP Jena. Within 4GABIS, ions are accelerated from a plasma source with voltages of up to 30 kV in a beam of around 180 mm diameter. Currently, 4GABIS is not completely characterized for all of the available acceleration parameters. Hence, the first goal of the experiments is to investigate the effect of grid voltages on the resulting shape of the beam profile. This will be measured both directly with a movable faraday cup and indirectly via resulting sputter rates. The insights of this will subsequently be applied to establish ratios between the flux of ions hitting the target and the faraday cup in measurement position, respectively. Next to that, the impact of neutralisation of ions during their flight via charge transfer will be measured. From this, charge transfer cross sections can be calculated and compared with the literature. The combined results are to be integrated into a preexisting LabVIEW program to allow for insitu measurement of ion flux.
Summary of the main goals for this experiment:
 Understanding the shaping of a hotcathode glow discharge plasma
 Investigation of grid voltage parameters to affect the resulting ion beam
 Measurement of charge transfer cross section for collisions of ions and residual gas
 Combining parameters necessary for insitu monitoring of ion flux
Prerequisites:
 Basic understanding of hot cathode glow discharge and ion acceleration
 Basic knowledge of LabVIEW programming
 Good laboratory skills
 Interest in operating a unique ion source
Contact:
Supervisor: Johannes Kaufmann
Venue: Institute of Applied Physics, Beutenberg Campus (AlbertEinsteinStr. 15)
The topic is suitable for one or two students.

Investigating Laser Heating in 2D Materials
Two dimensional materials show some unique optical properties, many of which arising from the quantum confinement that leads to a strong binding of excited electrons and the positively charged hole. Some experiments, e.g. for the study of nonlinear optics and many body physics, require high laser excitation powers which leads to a problem that has so far not been studied in detail: local heating by the laser radiation. This is especially crucial in experiments where the excitation power is scanned from low and high, since the different temperatures will lead to secondary effects that make any interpretation difficult. To mitigate the heating effects or include the heating into the models appropriately, we first need to learn more about the magnitude of said temperature increase. In our labs we work with many different materials, wavelengthranges and temperatures from ambient down to 14 K and it can be expected that each configuration will be unique, but for our first investigation that will be detailed below, we will pick the class of 2D materials known as transition metal dichalchogenides (TMDs), because they possess a Raman peak that is known to be temperature sensitive.
In the experiment we will place the sample on a thermostat and perform a measurement of this Raman peak with very low excitation power which is expected to leave the temperature nearly unchanged. By tuning the temperature of the thermostat, a correlation of peak position and temperature can be established. After that, we repeat the experiments, only this time the thermostat remains fixed at the lowest temperature and the excitation power is increased. Again, the peak position is monitored, which yields the correlation between laser powerand peak position. By combining the two results we can determine the influence of laser power on temperature.
Objectives:
 Temperature dependence of Raman mode in TMDs
 Laser induced heating in TMD
Experimental techniques:
 Raman scattering
 Cryostat/thermostat
 Twodimensional materials
Contact:
Supervisor: M.Sc. Muhammad Hussain
Venue: GUFOS, IFK (Room E011)
The topic can be worked on by one or two students. Supervision is possible in English only.

LowCost Single Crystalline Metal Layers: Fabrication and Characterization
Single crystalline metal layers on natural mica are often used in electronic devices such as transistors, solar cells, and sensors, due to their high electrical conductivity and mechanical stability. Additionally, they can be used as a substrate for growing other single crystalline materials, such as semiconductors, which can be used in electronic devices as well. The high thermal and chemical stability of natural mica also makes it an ideal substrate for a wide range of applications, such as in the aerospace and automotive industries. Overall, the costeffective fabrication of single crystalline metal layers on natural mica can have a significant impact on the development of new technologies and the improvement of existing ones.
The experiment aims to fabricate and investigate the properties of single crystalline metal layers using a thermal evaporation method. In this process, the metal material will be thermally evaporated onto a substrate of natural mica under specific conditions, such as temperature, pressure, and evaporation rate, to achieve single crystalline growth. The substrate will be carefully chosen, cleaned and prepared to ensure optimal growth conditions.
The characterization of the fabricated metal layers will be done using a combination of techniques including atomic force microscopy (AFM) and xray diffraction studies (XRD). The AFM will be used to observe the surface morphology of the metal layers, including the thickness, uniformity, and surface roughness. The XRD will be used to determine the crystal structure of the metal layers, including the crystal size, lattice spacing, and crystal orientation, as well as to identify any defects or impurities in the crystal structure.
The goal of the experiment is to understand how the thermal evaporation fabrication method and process conditions affect the properties of single crystalline metal layers and how such layers can be used in various applications such as electronics, catalysis, and sensing. The experiment will also help in understanding the relationship between the growth conditions and the crystal structure and will provide a better understanding of the fundamental physics of metal growth.
The main goals of this experiment are:
 Fabrication of single crystalline metal layers using thermal evaporation
 Investigation of the structural and morphological properties
Prerequisites:
 Familiarity with basic laboratory techniques
 Basic understanding of crystal growth and crystal structure
Methods:
 Thermal evaporation setup
 Atomic force microscopy (AFM)
 Xray diffraction studies (XRD)
Contact:
Supervisor: Dr. Marco Grünewald and Dr. Berit Marx
Language: German or English
Venue: FPraktikum and labs of the IOQ
The topic is suitable for one or two students.

NanoFabLab
Micro and nanotechnology forms the basis for a growing number of everyday objects and current scientific research. Many physical systems require a direct examination or at least a basic understanding of this technology chain.
The theoretical foundations are already taught at the FSU as part of the Micro/Nanotechnology lecture in the Physics or Photonics Master's programme and the associated seminar. Practical training has not yet been provided. This gap is to be closed by expanding the programme of the lab course.
The aim of this offer is to gain initial experience with an existing lithography line in the clean room and to jointly develop a concept for how this can be used for future teaching.
Contact:
Supervisor: Dr. Thomas Siefke
Venue: Clean room of the IFK and FPraktikum
The topic is suitable for one or two students.

Towards a quantum light source in NbOI2
Many modern quantum light sources for quantum technologies such as quantum cryptography, quantum key distribution and ghost imaging are based on the process of spontaneous parametric downconversion (SPDC). This process splits one pump photon into an idler and a signal photon and requires a material with a second order nonlinearity; it can be envisioned as the „inverse“ process of second harmonic generation (SHG). Current state of the art quantum light sources use periodically poled bulk crystals, in order to achieve necessary conversion efficencies. However, these bulky crystal make an implementation onto existing photonic structures, like fibres and waveguides, impossible.
Recently, the novel material class of layered ferroelectrics has emerged. Ferroelectrics show strong second order nonlinearity, independent of the layer number, and can be exfoliated to atomically thin layers. This culminated in researchers being able to build an ultrathin quantum light source from NbOCl_{2}, one member of the family of layered ferroelectrics.
In this series of experiments, we will investigate the nonlinear optical properties, namely second and third order nonlinearities, of the layered ferroelectric NbOI_{2}. We will theoretically and experimentally study the second and third order nonlinear response of NbOI_{2}, by performing second harmonic generation (SHG, the simplest second order nonlinear process) and third harmonic generation (THG, the simplest third order nonlinear process) measurements, focusing in particular on their power and polarization dependence. Finally, we will discuss the concept of angular momentum of light and we will experimentally study SHG and THG in NbOI_{2 }when the fundamental beam is tuned from linear to circular polarization.
Working plan:
Weeks 14: introduction to SHG in NbOI_{2}, dependence of SHG on thickness, input power and crystal axes, polarization resolved SHG (resolving crystal axes, outofplane SHG)
Weeks 58: introduction to THG in NbOI_{2}, dependence of THG on thickness, input power and crystal axes, comparison to SHG
Weeks 912: angular momentum of light, SHG & THG for linear to circular polarization
Objectives:
 Layered ferroelectrics: band structure, optical properties and crystal symmetry
 Nonlinear optics: basic theory, nonlinear susceptibility tensors for SHG and THG
 Polarization optics (Quarter wave plate, half wave plate…..)
Experimental techniques:
 Second harmonic generation (SHG)
 Third harmonic generation (THG)
 Low noise and lockin detection
Contact:
Supervisor: Paul Herrmann
Venue: GUFOS, IFK (Room E002)
The topic can be worked on by one or two students. Supervision is possible in English and German

Vacuum Coating of Thin Metal Layers
Thin layers are layers with thicknesses in the micrometer and nanometer range. Their physical parameters such as electrical conductivity often deviates from that of the bulk material, allowing for altered, tailored properties and new functionalities. In addition, the material savings are often of great economic importance. Well known is the application in the field of protection against environmental conditions, e.g. against corrosion or oxidation. However, thin layers are most important in microelectronics, where almost all components are manufactured using thinfilm technology. In optics, thin layers and layer stacks are used to influence the reflection and transmission behavior, but also the polarization. In particular, layer systems play a prominent role in Xray optics.
In the internship, metallic layers are usually deposited and characterized by different methods. Concrete topics and goals, amongst others taken from current research projects, are proposed by the supervisor at the beginning of the internship, but can be discussed and adapted depending on the interests.
Learning goals and content:
 Deposition of thin metal layers by means of various coating methods (sputter coating, thermal evaporation)
 Characterization of the layer properties (e.g., composition, roughness, crystalline properties) depending on substrate properties and coating parameters (e.g. chamber pressure, residual gas composition, process times, substrate heating)
 Introduction and application of various analysis methods
 Scanning Electron Microscopy (SEM) and Energy Dispersive XRay Analysis (EDX)
 Scanning Tunneling or Atomic Force Microscopy (STM, AFM)
 Auger Electron Spectroscopy (AES)
 Xray diffractometry (in cooperation with the Xray group)
Experimental equipment:
 Sputter coating system from Oxford Instruments
 Thermal evaporation system (selfmade)
 Mass Spectrometer for residual gas analysis
 Quartz layerthickness monitor
 Scanning Electron Microscope
 Atomic Force Microscope
 Scanning Tunneling Microscope
 Auger Electron Spectrometer
Contact:
Supervisor: Dr. Thomas Siefke
Venue: FPraktikum
The topic is suitable for one or two students.

Polymeric Nanoparticles for Targeted Drug Delivery
The recent emergence of nanomedicine has revolutionized the therapeutic landscape and necessitated the creation of sophisticated drug delivery systems. Polymeric nanoparticles sit at the forefront of numerous promising drug delivery designs, due to their unmatched control over physiochemical properties such as size, shape, architecture, charge, and surface functionality. Hence, a precise understanding of polymeric nanoparticles preparation and characterization is essential for optimizing the drug delivery system.
We will prepare polymeric nanoparticles with various sizes and crystallinities and characterize them by size investigation and morphology. The application of the materials is not just interesting for basic research but also promising for the targeted delivery of drugs with optimized structures.
The aim of this work is to develop a comprehensive understanding of polymeric nanoparticles as drug delivery vehicles, using the various nanoparticle designs and preparation methods. If you are interested in new, futureoriented frontier materials and physicochemical aspects and like to work experimentally, then join our international team.
Goals and context
 Creation of nanostructured polymeric materials
 Characterization and analysis of these materials
 Structure elucidation of the materials
 Structureproperty relationships of materials
 Insight into current research and development fields in nanotechnology and smartfunctional materials methods
Methods
 Advanced literature research
 Elaboration of nanoprecipitation methods
 Analysis of polymeric nanoparticles, using atomic force microscopy (AFM), electron microscopy (SEM, TEM), UVVis, dynamic light scattering (DLS), etc.
 Determination of the mechanical properties of polymeric nanoparticles
Prerequisites
 Interest in materials science, nanophysics and soft matter physics
Contact:
Person in charge: Prof. Dr. Klaus D. Jandt
Supervisor: Dr. Chuan Yin
Venue: OSIM, Löbdergraben 32
The topic is suitable for two students. Up to tow student pairs (2 x2) may work on this topic.

Atomic processes driven by structured light beams
Context:
Modern day optical techniques have enabled physicists to structure the intensity, phase and polarization of the light beams. For example, LaguerreGaussian and Bessel light beams have structured intensity profile. Thus, these light beam’s intensity profile appears as donut with a dark center. These light beams are often referred as twisted light beams. In addition, these light beams can be used to construct vector light fields. These vector light fields demonstrate richer polarization pattern. Interaction of these light fields with atomic targets has found numerous applications in the field of optical metrology, quantum computers, atomic clocks and many more.
In this project, we wish to analyze photoexcitation of atomic cloud using various vector light modes and analyzing the properties of fluorescence radiation. Thus, in the end to have a detailed comparison between various light fields and atomic targets.
Goals of the project:
 To express the interaction phenomena in terms of density matrix theory
 To express vector light beams in LaguerreGaussian and Bessel basis.
 Description of the lightatom interaction using time dependent perturbation theory
 To better understand paraxial and nonparaxial nature of light fields.
Prerequisites:
 Knowledge of Quantum Mechanics
 Programming skills: Julia or Mathematica.
Contact:
Person in charge: Prof. Dr. Stephan Fritzsche, TheoretischPhysikalisches Institut
Supervision: Shreyas Ramakrishna
Place: TheoretischPhysikalisches Institut & HelmholtzInstitut Jena, Frauenhoferstr. 8.
Per term, one or two students may work on the project

Dielectronic recombination of hydrogenic ions: A key to relativistic quantum physics.
The dielectronic recombination (DR) of multiply and highlycharged ions involves the capture of an electron due to the resonant excitation of another bound electron as well as their subsequent stabilization by photon emission. The DR process has been found essential for understanding the dynamics of highlyionized plasma in astrophysical objects, fusion reactors, and at several places elsewhere. In astrophysics, for example, DR affects the ionization balance of gas in galaxy clusters and the intergalactic medium and, hence, the formation of stars and largescale structures in the universe.
In this project, we wish to explore and compute the DR resonance strength for the capture of electrons by (selected) hydrogenic ions with medium or high nuclear charge, Z. This requires to determine and apply solutions to the Dirac equation as they are provided by several (atomic) codes. We wish to analyze the lowlying DR spectrum for such ions and to compare our theoretical predictions with available experimental data.
Goals of the project
 Recall the treatment of one and fewelectron ions in terms of wave functions.
 Formulate the DR resonances strength by means of twoelectron matrix elements.
 Describe the interaction of atoms with a weak radiation field.
 Understand and apply an existing (Julia) code in order to compute the DR strength and plasma rate coefficients.
 Optional: Compare different theoretical models and how well they compare with experiment.
Prerequisites:
 basic knowledge of quantum mechanics
 programming skills (Python, Julia, C)
Contact:
Supervision: Prof. Stephan Fritzsche, TheoretischPhysikalisches Institut
Where: TheoretischPhysikalisches Institut & HelmholtzInstitut Jena, Frauenhoferstr. 8.
Per term, one or two students may work on the project

Machine Learning for Conserved To Primitive Conversion
The relativistic Euler equations are nonlinear partial differential equations for the evolution of relativistic fluids, which can generically form shocks, where characteristic curves intersect. Certain numerical schemes designed to solve such problems require the equations to be written as conservation laws. Such conservation laws introduce a set of evolved "conserved'' variables, alongside the "primitive'' variables, which
characterise the fluid from the perspective of a comoving observer. Both sets of variables are required to numerically evolve the system of equations, however the map from conservative to primitive variables cannot be written in a closed form. This requires a numerical solution to this problem. Historically this is performed with a root finding algorithm such as the NewtonRaphson method. In this project the student will investigate the use of machine learning techniques to solve this problem and compare their accuracy and speed to traditional methods.Goals and Context
 Understand the Special Relativistic Euler Equations for relativistic fluid flow, and the relavance of conservative numerical schemes for shock capturing.
 Achieve a basic understanding of thermodynamical equations of state for relativistic fluids.
 Investigate the inversion of conserved fluid variables to primitive fluid variables through numerical techniques.
 Solve the problem of conserved to primitive variable conversion for an ideal gas through the NewtonRaphson method.
 Train a neural network to perform the same variable conversion.
 Compare the performance and accuracy of the methods you investigate.
Methods:
The students will numerically convert a set of conservative variables to the corresponding primitive variables for a set of test data corresponding to an ideal gas, using first traditional root finding approaches, and then by training a neural network to perform the inversion. The project will proceed following a guided sequence of tasks:
 Study of the relativistic Euler equations, the LaxWendroff theorem, and the necessity of conservation law formulation.
 Study of the ideal gas equation of state and the necessity of numerical
conserved to primitive variable inversion.  Constructing a dataset of corresponding conserved and primitive variables.
 Solution of the variable inversion problem using a root finding algorithm such as the NewtonRaphson method.
 Training of a neural network on a training dataset, and testing its accuracy on a testing dataset.
 Comparing the performance of the two above approaches in speed and accuracy.
 Investigating improvements of the neural network approach through altering the network hyperparameters.
Python is strongly recommended as a coding language for this project due to the availability of machine learning packages such as PyTorch and TensorFlow.
Prerequisites:
 Basic knowledge of numerical solution of algebraic equations
 Basic programming skills
 Basic knowledge of Machine Learning techniques helpful
Contact:
Person in charge: Prof. Dr. S. Bernuzzi
Supervision: Dr William Cook (`william.cook@unijena.de`)
Place: Abbeanum, Fröbelstieg 1
Per term, one or two students may work on the topic.

Modern Topics in Quantum and Gravitational Theories
Possible topics within this project are:
 Entanglement and its entropy measures in quantum mechanics
 Supersymmetric quantum mechanics
 Magnetic monopoles and quantization of electric charge
 Magnetic monopoles in theoretical condensed matter physics: From the Berry phase in quantum mechanics to the field theoretical description of Weyl semimetals
 Do particles exist interpolating between a fermionic and a bosonic behaviour? Anyons and their description in terms of ChernSimons theory.
 Hawking radiation and evaporating quantum black holes*
*basic knowledge of general relativity and quantum field theory required.
Contact
Supervision: Prof. Dr. Martin Ammon
Venue: TheoretischPhysikalisches Institut, Fröbelstieg 1 (Abbeanum)
One or two students may work on this topic per term.

Polarization transfer in Compton Scattering
Compton scattering is the inelastic scattering of a photon on a free electron, in which a change in the wavelength of electromagnetic radiation is observed.The Compton effect is one of the cornerstones of quantum mechanics, which accounts for both wave and particle properties of light and matter. It is well known that the cross section of this process, described by the KleinNishina formula, depends on the energy and suggests that Compton scattering is very sensitive to the polarization of incident radiation. This sensitivity is the basis of Compton polarimetry, which is currently widely used for research in nuclear and atomic physics, for example in the Helmholtz Institute Jena.
While the standard KleinNishina formula is derived for the simplest case of light scattering by an electron at rest, in this project we investigate the case where the target electron has some momentum distribution. This socalled impulse (or momentum) approximation is a good approach for understanding the Compton scattering by weakly bound atomic electrons, which is required to analyze modern polarimetry experiments. In the proposed project, we will examine different models of electron momentum distribution and study how they affect the energy distribution and polarization of scattered photons. Our theoretical predictions will be compared with new experimental data, obtained at the PETRA III synchrotron in Hamburg
Goals of the project
 Theoretical analysis of the Klein–Nishina formula and of its predictions
 Derivation of the basic expressions of the impulse approximation
 Investigating how the polarization of scattered photons depends on the energy and polarization of incident photons
 Comparision of different theoretical models of momentum distribution and selection of the best approximation for modeling experimental results
Prerequisites:
 basic knowledge of quantum mechanics
 programming skills (Fortran, Mathematica, Pyton)
Contact:
Supervision: Dr. Anna Maiorova (group Prof. Dr. Stephan Fritzsche)
Where: TheoretischPhysikalisches Institut & HelmholtzInstitut Jena, Helmholtzweg 4
Per term, one or two students may work on the project

Rigorous Numerical Simulation of QuantumPhotonic Nanostructures
Goals and context
The strong coupling of light to quantum systems relies on the confinement of electromagnetic fields to subwavelength volumes. This can be achieved by hybrid nanophotonic quantum systems, in which photonic nanostructures support tightly confined electromagnetic resonances. Computer simulations are an essential part of this research since the fabrication of nanoscopic structures is challenging and the experimental characterization of optical fields at the few photon level with nanometer resolution is equally complicated. Therefore, reliable simulation methods are required to calculate the electromagnetic response of nanostructured matter in advance. Since we are dealing with structures in the subwavelength range, "rigorous" methods are needed, which solve Maxwell´s equations without any approximation. Different approaches have explored for certain classes of nanophotonic structures (micro and nano cavities, metasurfaces, nanoantennas).
Methods
The students will implement and use a rigorous numerical method (FDTD or FEM) for the solution of electrodynamic problems. They will either use one of the existing professional implementations of such methods or will be working on their own implementation in a programming language suitable for highperformance computing. The method will be used to simulate the behavior of a nanophotonic structure and to investigate the coupling to quantum systems.
Programming can be done in any language preferred by the students, but Python and Matlab are supported by existing implementations.
Prerequisites
 Basic knowledge of electrodynamics and related partial differential equations
 Basic knowledge of optics
 Basic knowledge of numerical methods
 Familiar with at least one programming language supporting numerical simulations (preferred Python or Matlab)
Contact:
Person in charge: Prof. Dr. Thomas Pertsch
Supervisor: Dr. Ángela Barreda
Place: Abbe Center of Photonics, Campus Beutenberg
Per term, one group of one or two students may work on the topic.

Simulating a quantum computer
Goals and Context of the project
Quantum computers promise a runtime advantage compared to their classical counterparts for certain tasks. However, currently existing quantum devices operate with moderate numbers of qubits and are prone to errors due to experimental noise and decoherence. To show that quantum computers provide an actual advantage requires outperforming the best algorithms for simulating quantum dynamics on classical computer, which led to a race between scaling up quantum hardware and improving classical simulation algorithms.
The goal of this project is to build a classical emulator of quantum circuits and to use it to simulate one of the major quantum algorithms. Also, you will explore how to model noise and errors in quantum devices. The focus of the project can be adapted depending on pace and interests of the students.
Methods
 Quantum gates, quantum circuit model, quantum algorithms
 Open system dynamics simulation through quantum channels/Lindblad mater equation
 Numerical methods for linear algebra: Sparse matrices, eigenvalue problems
 Numerical solution of ordinary differential equations, numerical integrators
 Visualization tools for numerical data
 Use of libraries for quantum circuit emulation like qiskit, qutip etc.
Instructions will be provided in Jupyter notbooks with code examples in Python. If preferred, another programming language can be used.
Prerequisites:
Solid knowledge quantum mechanics
Basic knowledge of numerical methods
Familiarity with Python programming language and use of numpy/scipy libraries (or another programming language suitable for numerical simulation such as Julia, Matlab,...)
Basic knowledge of quantum optics is useful
Contact:
Person in charge: Prof. Dr. Martin Gärttner
Supervisor: Adrian Aasen, Prof. Dr. Martin Gärttner
Place: IFTO, Abbeanum
Per term, one group of one or two students may work on the topic.

Wave Equation
Goals and context
 Basic concept of hyperbolic partial differential equations (PDEs) and the initialboundary value problem (IVBP)
 Finite differencing methods for derivative approximation
 Methodofline for timedomain PDEs with RungeKutta timesteps
 Numerical implementation of methods to solve multiD PDEs
 Concepts of numerical stability and convergence
Methods
The students will solve the IBVP with the wave equation in 1+1 and 2+1 dimensions (one time dimension and one and two spatial dimensions) numerically. The project has different sequential steps:
 Wave equation and reduction to first order system
 Characteristic analysis and wellposedness
 Finite differencing approximation of derivatives and convergence
 RungeKutta time integrators
 Solution of IBVP withthe 1+1 wave equation and periodic boundaries using the method of lines
 Stability and convergence
 IBVP with open boundaries and Sommerfeld boundary conditions
 Wave equation with a potential: the ReggeWheeler equation, scattering of graviational waves off a black hole and quasinormal modes
 More spatial dimensions: the 2+1 wave equation
Students can code in their preferred language, although Python is strongly recommended (open sources, simple and optimal for visualizations).
Prerequisites
 Basic knowledge of partial differential equations
 Basic programming skills
Contact:
Person of charge: Prof. Dr. S. Bernuzzi
Supervision:
Place: Abbeanum, Fröbelstieg 1 or PAF Computerpool
Per term, one or two or three students may work on the topic.

GammaRay Burst Afterglows (not available in WS 24/25)
illustration of the Swift satellite (top left); host galaxy of GRB 171205A and associated GRBSN 2017iuk (top right); light curve of GRB 921003 (bottom left); GRBafterglow light curve of GRB 150413A (bottom right)Content
From the discovery of the first GammaRay Burst (GRBs) in 1967, it took nearly 30 years to discover an optical transient related to a GRB, which allowed to place them at cosmologic distances. Since the 90's our knowledge of those cataclysmic events (emitted energy in gammarays: ~10^{51}  10^{53} erg) has drastically expanded. We know today that these shorttime gammaray sources (duration: a few 0.1 sec to several 100000 sec) can be found at redshifts z = 0.0085 to 9.4 (correlates to light travel time of 0.12 Gly to 13 Gly) and can be divided into two categories (long and short burst). Whereas long bursts (duration > 2 sec) are related to a special variant of type Ic supernova and short bursts (duration < 2 sec) are produced by the merger of two compact objects (preferably two neutron stars). The creation of the gammaray burst itself can be described within the fireball model by the collision of multiple shells traveling at highrelativistic velocities. After the burst, one can observe the afterglow of the GRB (from XRay to the Radio), which arises from the interaction of the shells and the interstellar material (ISM) and can be observed for several days to weeks.
The Project will focus on diffent aspects and caracteristics of the optical/NIR transients that follows the appearance of a GRB and the porperties of their host galaxies.
Tasks and Learning goals
 Reduction of photometric data in the VIS and NIR
 Analysis (photometry and astrometry) of photometric data
 Modeling of Afterglow light curves to derive the main properties of the transient(time and spectral evolution)
 search and modelling of Supernova components that can be found in the light curve
 investigating the properties of the GRB host galaxies (e.g. mass, age of the dominant stellar population, star formation rate)
 search within public archives for additonal data (data mining)
 deepening the understanding of relativistic outflows, Supernovae and the host galaxies of those events
 Observations at the TLS Tautenburg with the 2m Schmidt Telescope, if weather conditions are acceptable
Organisation:
Supervision: Dr. habil Sylvio Klose; Dr. Sebastian Schmidl
Location: Thüringer Landessternwarte Tautenburg (TLS Tautenburg) and/or FPranktikum (please contact S. Schmidl for further informations)
Students can consider for example, to spend one day every two weeks in Tautenburg to work on the project.

NBodySimulation of Planet Dynamics (not available in WS 24/25)
Context and goals:
In this project, mutual gravitational perturbations in systems containing stars, planets, and minor bodies are studied. Depending on the scenario and configuration, these perturbations can lead to different types of short and longterm phenomena: resonances and chaotic behavior as well as secular effects. Possible examples for specific scenarios include: capture in and release from orbital resonances; longterm stability of planetary systems; Lyapunov exponent and chaotic motion; influence of small perturbers on chaotic systems; secular perihelion drift in multiplanet systems; Kozai mechanism. For each specific problem, analytic approximations are available and can be used for comparison with the numerical results.
Methods:
A handful of numerical integrators is available, covering a set of different algorithms (BulirschStoer, RungeKutta, Everhart, (hybrid) symplectic) and scenarios. The integrators can be compared with respect to their precision and speed. Simulation results can then be visualized and statistically examined with selfmade programs/scripts.
Instructor: Dr. Torsten Löhne
Venue: Astrophys. Inst. and Unisternwarte, Haus 2 (Schillergässchen 3)
The complex topic can be worked on by one or multiple students. The actual tasks will be adapted.

The Origins of Supernova Remnants
Stars are mostly born in open clusters and spend a significant part of their lives as members of a cluster. An open cluster contains dozens or hundreds of stars formed at nearly the same time from the same nebula and loosely bound by mutual gravitational attraction.
The supernova progenitors, massive stars, form in the cores of open clusters. Twenty percent of them are thought to be ejected due to the strong tidal interactions, while the rest remain inside the cluster. Although the massive stars undergo a supernova and die at young ages (<50 Myr), many wellstudied supernova remnants (SNRs) are not directly linked to any open cluster despite the short (<100 kyr) maximum time passed after the supernova. This could be either because the cluster has not yet been detected or has already been dispersed, or the progenitor has been a runaway star and had already left the parent cluster. Yet, in the former two cases, the birth cluster can be discovered.
The cluster members share similar distance, age, metallicity, extinction, and velocity. Therefore, the differences in apparent brightness among members are due only to their intrinsic luminosities, thus their masses. The distances and the transverse velocities of the stars can be derived from the astrometric parallax and proper motion values, respectively, measured by the Gaia Satellite. The colormagnitude (HertzsprungRussell) diagram of the cluster members indicates the age, metallicity, and extinction. The most massive and hottest stars of the cluster evolve faster, move away from the main sequence in the colormagnitude diagram, and become cooler giants and/or supergiants. The position of the turnoff from the main sequence can be used to estimate the age of the cluster. To identify the properties of the members as well as the cluster variables, the colormagnitude diagram is fitted by a theoretical isochrone calculated for certain stellar evolution models and initial mass functions. However, the parameters determined by the isochrones must be tested by spectroscopic observations of the cluster members. The atmospheric parameters of the members derived from their spectra narrow the uncertainty of theoretical isochrones.
By detecting and studying the birth cluster, the SNR progenitor masses and metallicities can be found. This information is important to classify the SNRs and their neutron stars, if there are any.This project aims to teach students how to determine the properties of the open clusters using astronomical catalogs, stellar evolution models, stellar kinematics, observations, data reduction, and analysis, as well as SNR and shock physics.
Tasks
 Searching for a positional link with the SNRs and the already known clusters through a catalog search
 Selection of cluster members regarding their positional and kinematic properties
 Setting the colormagnitude diagram of the clusters or loosely groups using optical and nearinfrared photometry from various catalogs
 Spectral observation, data reduction and analysis of the brightest members
 Measuring the effective temperature, surface gravity and metallicity of the stars
 Determination of the extinction, the cluster age, and the progenitor mass by the isochrone fitting.
Contact:
Supervisor: Dr. Baha Dincel
Location (night observation): University Observatory in Großschwabhausen
Location (data reduction and analysis): Astrophysical Institute, Schillergäßchen 2, Jena
The tasks can be worked on by up to 3 students