Research Labworks for MSc

Information

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 summer semester 2024 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, March 13th, 2024 at 10 am.

At the end of the winter semester students submit (at the very latest on 15.08.2024) their results in form of a scientific paper draft.

The Organization of the research labwork is managed by the F-Praktikum office. For choosing a project, please contact us via physik.f-praktikum@uni-jena.de. Please do not send requests individually to project supervisors.

 

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Laserphysics/Optics

  • Advanced Experimental Microscopy - Super-Resolution 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 three-dimensional resolutions down to the nanometer range, resulting in the ever-growing field of optical super-resolution 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 cell-biological 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 diffraction-limited and super-resolution
    • Preparation of fluorescently labeled, biological samples
    • 3D & multi-colour 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)
        • Single-Molecule 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 super-resolution 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 2 students each.

     

  • Advanced techniques for stabilization of optical cavities

    Advanced techniques for stabilization of optical cavities

    In the realm of advanced scientific research, the exploration of precise measurement techniques and the development of stable optical systems have emerged as crucial endeavors. These fields have witnessed remarkable progress, enabling breakthroughs in various scientific disciplines and pushing the boundaries of our understanding. Precise measurement techniques, coupled with ultra-stable optical systems, have revolutionized fields such as quantum optics, spectroscopy, and fundamental physics research. These techniques allow us to probe the fundamental properties of matter and light with unprecedented accuracy and precision. Additionally, they enable the detection and measurement of elusive phenomena such as gravitational waves, opening up new avenues for exploring the mysteries of the universe. At the heart of these precise measurement techniques and stable optical systems lie advanced stabilization methods for optical cavities and lasers. Optical cavities, with their ability to enhance light-matter interactions, play a crucial role in achieving high-precision measurements. Stabilizing these cavities ensures their reliability and accuracy, enabling precise control over photon generation and manipulation. Our focus will extend beyond specific applications and delve into the general principles and techniques involved in stabilizing these optical systems. We will explore advanced stabilization methods such as the Side-of-Fringe (SOF) locking technique and the Pound-Drever-Hall (PDH) locking technique, which are widely applicable 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 mode-matching optics of a cavity by using ABCD matrix.
    • Explore the Side-of-Fringe (SOF) locking technique for cavity stabilization.
    • Explore the Pound-Drever-Hall (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.
    • Electro-optic modulators for phase modulation in the PDH technique.
    • Lock-in amplifiers for demodulation and proportional-integral (PID systems) for feedback control.
    • Data acquisition systems for recording and analyzing the locking signals.

    Place:            Fraunhofer IOF institute

    Supervision: MSc. L. Gonzalez & MSc. M. Leyendecker

    For this experiment two students are recommended.

  • Beyond the Visible: Infrared Fourier Spectroscopy in Molecular Physics

    A Fourier spectrometer in the simplest realization resembles a Michelson interferometer, however, with the ability of a controlled variation of the optical path lengths, e.g., by shifting one or multiple mirrors. The resulting intensity variation at the interferometer output, known as an interferogram, contains information about the spectral distribution of the incoming light. One of the primary advantages is its ability to simultaneously capture a wide range of frequencies in a single measurement, resulting in rapid and high-resolution spectral data. It is especially valuable in situations where conventional dispersive spectroscopy methods may be time-consuming or impractical, for instance in state-of-the-art infrared (IR) spectroscopies.

    In this experiment, students will have the opportunity to upgrade an existing Fourier spectroscopy setup to operate in the infrared (IR) spectral region. This will involve the procurement and integration of IR-specific components, including appropriate detectors, IR light sources, and optical elements. Additionally, they will conduct initial experiments to investigate the IR absorption characteristics of molecular gases.

    Teaching Goals and Content 

    • To modify and enhance an existing spectroscopy setup, adapting it for IR spectroscopy
    • To learn fundamental principles and applications of Fourier spectroscopy
    • To get hands-on experience in using specialized IR spectroscopy equipment
    • design, conduct, and analyze experiments related to the IR absorption of gases

     Prerequisites

    • Knowledge and interests in basic optics, interference and high-resolution spectroscopy
    • Good experimental skills

     

    Supervisor: Dr. Joachim Hein

    Place:         F-Praktikum

    For this experiment one or two students are recommended.

  • Entangled Photons Sources from Scratch – Design and Characterization

    Generation of single photons and Bell states has been a central concept for explaining EPR paradox, proposed by Einstein in 1935. Often termed as spooky action at a distance, this phenomenon has now become practically understandable, thanks to the development of efficient entangled photon sources in past two decades. Entangled photon source

           
           

    The aim of this lab work is to give an intuitive understanding of single photon generation with non-linear materials and quantum entanglement from an experimental point of view. An analysis of factors like phase matching conditions for non-linear materials and their tuning with temperature, optical alignment, evaluation of correlation functions and analysis of single photon and entangled state.

         
         
       
       
         
           
               
               
               

    Goals

    Content

    Bell states of light and their generation

    Concepts with an overview of the course.

    Fundamentals of designing a single photon source

    Hardware and opto-mechanics selection, calculations of various beam parameters, optical alignment.

    Characterizing a source

    In terms of spectra, photon generation rate and efficiency.

    Demonstration of 2 photon interference-The Hong Ou Mandel (HOM) effect

    Determining the purity of single photons.

    Computation of coherence time of single photons.

    Transitioning to an Entangled photon source (EPS)

    Employing birefringent media to achieve an entangled state.

    Entangled state division into two channels for further analysis.

    Characterization of the EPS

     

    Development of a polarization analysis module.

    Indistinguishability analysis in polarization mutually unbiased basis for the above two channels.

     

     

       
         
         
             
             
             
       
       
       
       

    Experimental Techniques and Equipment 

    •  Nonlinear crystals- periodically poled ppktp and crystal heating oven for photon generation and temperature tuning, respectively.
    •  Si avalanche single photon detectors and timing correlator (Time tagger) for correlation measurements.
    •  Optics-lenses, mirrors, polarizers, waveplates, beam displacers, birefringent media (ppktp, YVO4, calcite), for setup construction and subsequent operation.
    •  Grating spectrometer for spectral data recording.
    •  Michelson Interferometer- design and illustration of operation.

    Supervisors:   MSc. Purujit Singh Chauhan, MSc. Sabine Hausler

    Place:            Fraunhofer IOF institute and ACP labs

    For this experiment two groups of two students are recommended.

  • Femtosecond Laser

    Nowadays the generation of ultra-short 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 ultra-fast processes, to perform ultra-precise spectroscopy, or to generate extreme electrical and magnetic fields through ultra-high light intensities, but they are also applied in material processing, medicine, especially in ophthalmology. Nevertheless, the generation and metrology of ultra-short 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 non-linear optics and frequency conversion, that requires phase matching to get reasonable efficiencies. Second harmonic generation and two-photon absorption are used for pulse characterization by auto-correlation here. The limitations of the auto-correlation 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 solid-state lasers (Ti:sapphire)
    • Cavity stability and longitudinal cavity modes
    • Dependence of output power on pump power
    • Generation of femtosecond pulses by Kerr-lens mode-locking
    • Compensation of group velocity dispersion in optical cavities
    • Impact of spectral phase on pulse duration and temporal pulse shape
    • Measurement of band-width and duration of laser pulses
    • Application of Fourier-Transform to explain pulse stretching and compression
    • Interferometric and intensity auto-correlation and their limitations for pulse characterization
    • Measurement of group velocity dispersion (GVD) of several materials

    Experimental techniques and equipment

     

    • diode-pumped, frequency-doubled 5W Nd:YV04-laser as pump source
    • homemade Ti:sapphire femtosecond laser with prism GVD compensation
    • external prism pulse compressor
    • optical spectrometer
    • second harmonic generating auto-correlator
    • photodiodes, powermeter and oscilloscope

    Supervisor:   Dr. Joachim Hein

    Place:            F-Praktikum

    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 high-resolution 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 problem-solving ability
    • Basic knowledge in programming, ideally in Python or Matlab

    Supervisor: Dr. Martin Wünsche

    Place:         Max-Wien-Platz 1

    For this experiment two students are recommended.

  • Polarization dependence of high-order harmonic generation in semiconductors

    Since the first theoretical prediction in 2006 and experimental observation in 2010, high-order harmonic generation (HHG) in solids is one of the very hot topics in modern nonlinear optics. The realm of conventional (non-resonant) nonlinear optics is an interaction of relatively low intensity light waves with a medium, thus any nonlinear phenomenon, like second- or third-order harmonic generation, is described within the perturbation theory. In the case of interaction with ultrashort pulses, the origin of the nonlinearity is the nonlinear polarization of electron charge distribution, localized near the atoms in the crystal lattice. In contrast, strong field interaction with solids proceeds in a regime when laser field strength approaches the damage threshold of the material. It results in breakdown of the perturbation theory and substantial population of the conduction band, leading to formation of an electron/hole wavepacket that can be driven by the laser field through the crystal with an amplitude that is much larger than the lattice constant. The corresponding highly nonlinear, non-local in real space and in the energy-momentum space response, periodically driven by the strong laser field, results in HHG with harmonic orders well beyond perturbative second or third order.

     The goal of the suggested project is the experimental investigation of HHG in crystalline solids as a function of the laser polarization and symmetry of the crystal. The tasks of the project are: 1) setting up the optical setup for HHG by femtosecond mid-IR laser pulses; 2) measurements of harmonic spectra, generated by ultrashort mid-IR laser pulses in c-cut and a-cut thin ZnO crystals, in dependence on the angle between the linear laser polarization and the crystal axis; 3) measurements of harmonic spectra in dependence on the ellipticity of the laser polarization by changing the polarization from linear to circular and different crystal orientations.

    Methods

    • High power lasers
    • Setting up optical experiments with modern components
    • Logging, analyzing and interpretation of measured data, comparison to literature results

    Prerequisites

    • Basic knowledge about laser and solid state physics
    • (nonlinear) optics, experimental skills, good knowledge of English

    Organization

    Person in charge: Prof. Dr. Christian Spielmann

    Supervision: Dr. Daniil Kartashov

    Place: Labs of the IOQ/QE at Max-Wien-Platz 1

    Per term, two students may work on the topic

  • Nonlinear crystals investigation for quantum optical systems (not available in WS 23/24)

    Quantum technologies are emerging in the last years, as they offer a surpassing performance to their classical analogues. Some applications are using entangled and correlated photons, to significantly enhance signal to noise ratio in microscopy and imaging, compute exponentially more data in quantum computers, and achieve unbreakable communication protocols by the laws of physics.

    Second order nonlinear crystals and waveguides are the essential building block of such systems. Correlated photons are created based on spontaneous parametric down-conversion (SPDC) in bulk materials, such as Potassium Titanyl Phosphate (KTP), Lithium Niobate (LN), and Beta Barium Borate (BBO). In this lab work, the performance of materials with different properties is to be investigated, according to their efficiency of creating SPDC photons, temperature tuning and spectral characterization of SPDC.

    Teaching Goals and Content 

    • Laser beam alignment for single mode fiber coupling
    • Working principle of quasi phase matching in periodically poled crystals
    • Temperature tuning of periodically poled materials
    • Investigating the behavior of temperature vs. output spectrum
    • Simulation of Gaussian beams in optical components (ABCD matrix formalism)
    • The effect of using different lens focal lengths on single photon coupling

    Experimental Techniques and Equipment 

    • Continuous wave pump laser at 405 nm and 775 nm
    • Polarization control and polarizing beam splitters
    • Single photon detectors
    • Spectral characterization with an optical spectrometer
    • Temperature control of the crystals
    • Two photon interference of Hong-Ou-Mandel
    • Some other equipment: Photodiodes, powermeter and oscilloscope

    Supervisors:   MSc. Sakshi Sharma, MSc. Grucheska Rosario, MSc. Rana Sebak

    Place:            Fraunhofer IOF institute

    For this experiment two students are recommended.

  • Nd:YLF Shortpulsed - Laser (not available)

    Flash lamp pumped Nd:YAG (also Nd:glass or Nd:YLF as used for this experiment) lasers are still the work horses used for laser material processing, i.e. cutting, drilling, welding, soldering, or forming of workpieces. Additionally, they are often used as a pump source for optical-parametric or femtosecond laser amplifiers in science or for instance as a driver for inertial confinement nuclear fusion. The latter applicationcomprises the world's largest lasers generating up to some MJ pulse energy in only some ns in time. Because of the acceptable efficiency, low cost of ownership, and flexibility of flash lamp pumped solid state lasers for the generation of high pulse energies, they are still widely used today. This kind of lasers have the capability to generate microsecond, nanosecond and even picoseconds pulses by techniques that are universal for short pulse lasers. The underlying basics for these techniques are taught within this experiment together with pulse characterization using auto-correlation and basics of nonlinear optics as well as laser pulse amplification. Since with the rare-earth element neodymium an almost ideally four-level laser schem can be realized, it perfectly serves as a model to understand laser dynamics in more depth.    

    Teaching goals and content 

    • working principle and properties of solid-state lasers (Nd:YLF)
    • spiking in free-running mode
    • dependence of output power on pump power
    • working principle of a Pockels cell
    • generation of short pulses by Q-switching
    • non-linear optics: second harmonic generation (SHG) and phase matching principle
    • generation of picosecond pulses by 'non-linaer mirror' mode-locking
    • measurement of pulse width by intensity auto-correlation with SHG
    • optical amplification of short pulses in flash lamp pumped rod amplifiers

    Experimental techniques and equipment

     

    • flash lamp pumped Nd:YLF-laser with four laser heads
    • cavity with SHG for mode-locking
    • cavity with Pockels-cellfor q-switching
    • motorized SHG auto-correlator for ps-pulses
    • energymeter, photodiodes, oscilloscope

    Supervisor:   Dr. Joachim Hein

    Place:            F-Praktikum

    For this experiment two students are recommended.

     

Solid State Physics

  • Electron Diffraction of two-dimensional 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 X-rays 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 X-rays. 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 low-energy 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 single-crystal 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
    • highly-ordered 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)
      • MCP-LEED (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

    Supervisor: Dr. Felix Otto    

    Venue: Labs of AG Fritz (ZAF)

    The topic is suitable for two students.

  • Exfoliation and Optical Characterization of 2D materials

    The realization of the first monolayer graphene flake in 2004 has triggered a vast amount of experimental and theoretical research, leading also, among other results, to the discovery and fabrication of several other atomically thin materials, such as the semiconducting transition metal dichalcogenides (TMDs). Besides the interest for fundamental science, 2D materials play an important role from the technological point of view and will likely contribute to develop the next generation of electronic, optoelectronic, and energy storage devices.

    In this series of experiments, graphite and TMDs bulk crystals will be exfoliated and transferred onto a silicon/silicon dioxide substrate and characterized by optical spectroscopy methods. The students, after successful mechanical exfoliation and transfer, will learn how to identify samples with different number of layers using the optical contrast method. Subsequently, they will proceed to further characterization by Raman and photoluminescence (PL) spectroscopy. Finally, students will fabricate layered heterostructures (TMD/graphene) and they will perform power-dependent PL measurements to study electron interactions and interlayer charge transfer.

    Thus, the tentative working plan includes the following lectures and experiments:

    Weeks 1-3

    • Introduction to TMDs: band structure, optical properties, fabrication methods
    • Theory: identification of number of layers in TMDs from optical contrast, Raman and PL spectroscopy
    • Exfoliation of TMD crystals and identification of the number of layers by optical contrast and PL spectroscopy

    Weeks 4-6

    • Introduction to graphene: band structure, optical properties, fabrication methods
    • Theory: identification of number of layers in graphene from optical contrast and Raman spectroscopy
    • Exfoliation of graphite crystals and identification of the number of layers by optical contrast and Raman spectroscopy

    Weeks 7-10

    • Fabrication of a layered heterostructures (TMD/graphene)
    • Power-dependent PL measurements of monolayer and heterobilayer samples

    Weeks 11-14

    • Data analysis and discussion
    • Report writing

    Objectives

    • Graphene and TMDs: fabrication and optical properties
    • Laser: basics of laser science
    • Optical characterization: optical contrast, Raman and PL spectroscopy

    Experimental techniques

    • Mechanical exfoliation and deterministic transfer of graphene and TMDs
    • Optical contrast, Raman and PL

    Supervisor: Muhammad Hussain

    Venue: GUFOS, IFK (Room E012)

    The topic can be worked on by one or two students. Supervision is possible in English only.

  • 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 so-called 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 widely-used 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, self-made CNT networks shall be tested in terms of their performance as gas sensors (FET setup). For this purpose, I-V curves are measured computer-aided 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 gas-phase 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: I-U, 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)
    • Computer-aided measurements of I-V curves

     

    Supervisor:      Dr. Marco Grünewald

    Venue:            F-Praktikum and labs of the IFK

    The topic is suitable for one or two students.  

  • Nonlinear Optics in Two-Dimensional Materials

    Nonlinear optics is a vital part of science and technology, widely used for frequency conversion, self-referencing of frequency combs, spectroscopy, sensing and ultrashort pulse characterization. Two-dimensional materials are ideal for nonlinear optics because they offer a strong optical response with nearly unlimited bandwidth. Additionally, due to their deep-sub wavelength thickness, flexibility and strength, they can be easily integrated into photonic platforms.

    In this series of experiments, we will investigate the nonlinear optical properties, namely second harmonic (SH) and third harmonic (TH) generation, of atomically thin semiconductors belonging to the category of transition metal dichalcogenides (TMDs). We will theoretically and experimentally study the SH and TH nonlinear response of TMDs, focusing in particular on their power and polarization dependence. In addition, we will discuss how the latter can be understood in a more general framework considering point group symmetries. We will study how SHG can be used for the characterization of crystal orientation and number of layers in naturally stacked TMDs. Finally, we will discuss the concept of angular momentum of light and we will experimentally study SHG and THG in TMDs when the fundamental beam is tuned from linear to circular polarization.

    Working plan:

    Weeks 1 -4: introduction to SHG in TMDs, dependence of SHG on layer number, input power and stacking, polarization resolved SHG (six fold patterns, resolving crystal axes and strain)

    Weeks 5-8: introduction to THG in TMDs, dependence of THG on layer number, input power and polarization, in comparison to SHG

    Weeks 9-12: angular momentum of light, SHG & THG for linear à circular polarization

    Objectives

    • 2D Materials and TMDs: 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 lock-in detection
    • Precise control and detection of the polarization state of light

    Supervisor: Omid Ghaebi

    Venue: GUFOS, IFK (Room E002)

    The topic can be worked on by one or two students. Supervision is possible in English and German

  • Particle-in-a-Box Model in Optical Spectroscopy

    Particle-in-a-Box Model in Optical Spectroscopy

    The particle-in-a-box model is a simplified but powerful representation used to explain quantum confinement effects. In this model, a particle, such as an electron, is imagined to be confined within a one-dimensional potential energy well, often resembling a rectangular box. The dimensions of the box, particularly its length, determine the quantized energy levels of the confined particle.

    Similar to electrons within a potential well, electrons within organic molecules can exhibit quantized energy states due to quantum confinement. Consequently, energy levels in molecules depend on their size and structural characteristics. Experimental evidence for the particle-in-a-box model shall thus be provided by means of absorption and photoluminescence measurements on suitable organic molecules.

    In order to include this experiment in the students’ lab (F-Praktikum) in the future, instructions shall be written that include background information, experimental procedures, materials needed, methods, safety precautions, and learning objectives. Designing and conducting experiments for students can not only deepen your own skills but also be a valuable contribution to the educational experience of future students.

    The main goals of this experiment are:

    1. Understanding the concept of quantum confinement and its significance in nanoscience and materials science.
    2. Relating the particle-in-a-box model to the quantization of energy levels in confined systems.
    3. Performing absorption and photoluminescence spectroscopy
    4. Experimentally validation the quantum confinement model by observing and interpreting optical spectra
    5. Create an instructional guide for conducting the particle-in-a-box model experiment in a students’ lab

    Prerequisites:

    • Basic Understanding of Quantum Mechanics
    • Electronic structure and properties of molecules (energy levels, etc.)
    • Knowledge about optical spectroscopy
    • Good laboratory skills and great care when experimenting with chemicals
    • Interest in designing a students’ experiment

    Supervisor: Dr. Marco Grünewald

    Language: German or English

    Venue: F-Praktikum

    The topic is suitable for one or two students.

     

  • 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 thin-film 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 X-ray 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 X-Ray Analysis (EDX)
      • Scanning Tunneling or Atomic Force Microscopy (STM, AFM)
      • Auger Electron Spectroscopy (AES)
      • X-ray diffractometry (in cooperation with the X-ray group)

    Experimental equipment

    • Sputter coating system from Oxford Instruments
    • Thermal evaporation system (self-made)
    • Mass Spectrometer for residual gas analysis
    • Quartz layerthickness monitor
    • Scanning Electron Microscope
    • Atomic Force Microscope
    • Scanning Tunneling Microscope
    • Auger Electron Spectrometer

    Supervisor:   Dr. Thomas Siefke

    Venue:           F-Praktikum

    The topic is suitable for one or two students.

  • Investigation of Multilayer Mirrors for X-Rays (not available in WS 23/24)

    Learning target and topics

    • Thin metal layers: deposition, characterization of the layer properties and structure
    • High vacuum technology
    • Introduction and application of various analysis methods
      • Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Analysis (EDX)
      • Scanning Tunneling or Atomic Force Microscopy (STM, AFM)
      • AugerElectronSpectroscopy (AES)
      • X-ray diffractometry

    Experimental equipment

    • Sputter coating system from Oxford Instruments
    • Thermal evaporation system (self-made)
    • Mass Spectrometer for residual gas analysis
    • Scanning Electron Microscope
    • Atomic Force Microscope
    • Scanning Tunneling Microscope
    • Auger Electron Spectrometer

    Supervisor:   Dr. Thomas Siefke, Dr. Berit Marx-Glowna

    Venue:           F-Praktikum, IFK and IOQ

    The topic is suitable for one or two students.

     

Material Science

  • Determination of crystallographic orientation-dependent osteogenic activity of TiO2

    Titanium and its alloys are the most commonly used materials for dental and orthopedic implants. The success of their implantation is determined by the level of osseointegration, i.e. integration into living bone. The process of osseointegration involves osteoblasts, whose adhesion is tightly regulated by the unfolding state (conformation) of adsorbed proteins such as fibronectin (Fn), which itself is known to depend on the biomaterial surface properties. Key surface properties that can affect protein adsorption include surface energy, hydrophilicity, and surface roughness. It should be noted that a titanium oxide (TiO2) layer spontaneously forms on the titanium surface, which comes into direct contact with the body environment and determines the course of the biological biological response.

    The goal of this project is to investigate how the arrangement of atoms on the TiO2 surface, and therefore its surface energy, influences the adsorbed Fn conformation, excluding the other material surface factors. This is a first step in determining how the crystallographic orientation of the TiO2 affects Fn-mediated osteoblast activity.

    In this project, students will be responsible for the preparation and further characterization of the adsorbed protein layer. Protein solutions of certain concentrations will be produced with the help of UV-Vis spectroscopy. Atomic force microscopy (AFM) will be used for the investigation of TiO2 surface topography and Fn structure. Moreover, TiO2 surface energy before and after Fn adsorption will be determined using AFM, to assess the Fn conformation-dependent material surface energy changes. Conformational changes of the adsorbed proteins will be additionally studied via attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR).

    Goals and context

    • Understanding the influence of material surface properties on biological phenomena
    • Protein concentration measurement and solution dilution
    • Determination of surface energy
    • Determination of surface energy
    • Characterization of protein structural changes upon adsorption on material surface
    • Nanomaterial characterization techniques

    Methods

    • Protein adsorption on TiO2 surface
    • UV-Vis to define protein solution concentration
    • AFM to detect and characterize protein structure
    • AFM to determine surface energy before and after protein adsorption
    • ATR-FTIR to characterize protein conformation

    Prerequisites

    • Interest in condensed matter physics, surface science, and materials science

    Person in charge: Prof. Dr. Klaus D. Jandt

    Supervisor:      Dr.-Ing. Maja Struczynska 

    Venue:            OSIM, Löbdergraben 32

    The topic is suitable for two students (pair). 

  • Consolidation of Titanium Oxide Powders - Microstructure Evolution and Analysis

    Surface science contributes to the improvement of materials and devices' usability where the interface plays a crucial role. The surface properties of titanium oxide (TiO2) are used in many fields of industry, e.g., the photocatalytic degradation of binder in paints or biocompatibility of bone implants. Powder pressing is one of the most commonly used methods in modern condensed matter materials engineering and is widely used to obtain TiO2 polycrystals. The final microstructure of the polycrystal depends on initial powder properties, such as grain size or shape, but also can be engineered by choosing the correct sinter parameters (e.g. time or treatment temperature).

    The aim of the project is to understand the microstructure evolution of polycrystalline samples after each of the production steps, i.e., pressing, sintering, and thermal etching. Special focus will be laid on the role of starting powder properties on sample microstructure evolution and advanced characterization methods, such as atomic force microscopy (AFM) and scanning force microscopy (SEM). In this project, students will prepare their own samples and carry out comprehensive sample characterization, from density and porosity determinations, through surface roughness measurements with AFM (before and after the thermal etching), to SEM-based microstructural-crystallographic characterization, namely electron backscatter diffraction (EBSD).

    Goals and context

    • Principles and application of isostatic presses
    • Concept of powder compaction and polycrystal formation
    • Effect of sinter parameters on density and grain size
    • Rutile pellets preparation
    • Surface reconstructions during thermal treatment
    • Grain orientation characterization
    • Comparison of different polycrystals obtained in the same process (influence of powder characteristics and thermal treatments)

    Methods

    • Isostatic powder pressing
    • Microscopical and Archimedes methods to determine density and porosity
    • Powder thermal processing
    • AFM to characterize topography and surface roughness
    • EBSD to determine the crystallographic orientation
    • Optical microscopy for surface structure observation

    Prerequisites

    • Interest in condensed matter physics, surface science and materials science

    Person in charge: Prof. Dr. Klaus D. Jandt

    Supervisor:      AOR PD Dr. Jörg Bossert 

    Venue:            OSIM, Löbdergraben 32

    The topic is suitable for two students (one pair). 

  • Switchable Antimicrobial Biomaterials

    Microbial and viral infections/contamination are significant problems in the health, mobility or food sectors. Novel materials can help to kill microbes or reduce microbial adhesion to surfaces. So far, most antimicrobial materials are static. We introduce the highly innovative concept of switchable materials.

    We will switch nano structured metals and materials of soft robotics and will identify suitable switching concepts, which are most effective against microbes.

    These completely new and fascinating materials are not only interesting for basic research, but also offer numerous application options in innovative technologies (nanorobotics), materials science and industry.

    The aim of this work is to develop from scratch metallic and organic materials for which light and/or temperature changes play key roles as an external movement stimulus and shape memory effects. Physical oscillations will be introduced to nanostructured materials. If you are interested in new, future-oriented frontier materials and physico-chemical aspects and like to work experimentally, then join our international team.

    Goals and context

    • Creation of nanostructured metals and polymers
    • Creation of new antimicrobial soft matter actuator materials (SMAM)
    • Characterization and analysis of these materials
    • Structure elucidation of the materials
    • Structure-property relationships of materials
    • Physical oscillation of materials
    • Insight into current research and development fields in nanotechnology and smart-functional materials methods

    Methods

    • Advanced literature research
    • Elaboration of metal and SMAM synthesis methods
    • Analysis of SMAM, using atomic force microscopy (AFM), electron microscopy (SEM, TEM), UV-Vis, CLSM, differential-scanning-calorimetry, XRD etc.
    • Building of novel small soft robots
    • Determination of the mechanical and switch properties of metals and SMAM
    • Time and progress allowing control of microbial adhesion tests

    Prerequisites

    • Interest in condensed matter physics, materials science and soft matter physics

    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 two student pairs (2 x 2) may work on this topic 

Computational Physics and Theory

  • N-Body-Simulation of Planet Dynamics

    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 long-term phenomena: resonances and chaotic behavior as well as secular effects. Possible examples for specific scenarios include: capture in and release from orbital resonances; long-term stability of planetary systems; Lyapunov exponent and chaotic motion; influence of small perturbers on chaotic systems; secular perihelion drift in multi-planet 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 (Bulirsch­-Stoer, Runge-Kutta, 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 self-made 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.

  • Wave Equation

    Goals and context

    • Basic concept of hyperbolic partial differential equations (PDEs) and the initial-boundary value problem (IVBP)
    • Finite differencing methods for derivative approximation
    • Method-of-line for time-domain PDEs with Runge-Kutta timesteps
    • Numerical implementation of methods to solve multi-D 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 well-posedness
    • Finite differencing approximation of derivatives and convergence
    • Runge-Kutta 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 Regge-Wheeler equation, scattering of graviational waves off a black hole and quasi-normal 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

    Organisation

    Person of charge: Prof. Dr. S. Bernuzzi

    Supervision: William Cook

    Place: Abbeanum, Fröbelstieg 1 or PAF Computerpool

    Per term, one or two or three students may work on the topic.

  • Strong Interactions on the Computer: Gauge Theory on the Lattice

    Context

    The strong interaction that binds the elementary particles in nuclear matter is responsible for most the mass of visible matter. The mass is generated due to the interaction strength and it is hence essential for the formation of our universe. Nevertheless its charges can not be observed at the scales of our everyday live due to confinement: at low energies, a free charge of the theory can not exist and only bound states of fundamental particles are observed. At high enough energies, on the other hand, the theory is rather simple due to a phenomenon called asymptotic freedom. This simple fundamental theory is specified by the guiding principle of local gauge invariance, a generalization of the gauge principle of electrodynamics.

    The confinement is an essential property of the theory, but it is not accessible by analytic perturbative methods. Some decades ago, the numerical techniques of Monte Carlo simulations on a space-time lattice have been developed. They are by now the most important methods to investigate the theory especially in the confined regime. This low temperature regime of bound state particles is separated by a deconfinement transition form a high temperature regime at which the fundamental constituents, the quarks and gluons, become relevant degrees of freedom.

    The aim of this project is to understand the theoretical foundations of gauge theories and explore properties of the theory in numerical simulations.

    Goals of the project

    • obtain understanding of theoretical foundations of gauge theories and strong interactions
    • understand the basics of lattice Monte Carlo simulations in quantum field theory
    • derive a program code for the simulation of SU(2) pure gauge theory (some skeleton code and examples are provided)
    • investigate the deconfinement transition
    • optional extensions: improved algorithms, static quark-antiquark potential and further observables

    Prerequisites:

    • basic knowledge of quantum field theory
    • programming skills (C++, C, Fortran)

    Contact:

    Supervision: Dr. Georg Bergner, Theoretisch-Physikalisches Institut

    Where: Theoretisch-Physikalisches Institut, Fröbelstieg 1 (Abbeanum)

    Per term, one or two students may work on the project

  • 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 Chern-Simons 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: Theoretisch-Physikalisches Institut, Fröbelstieg 1 (Abbeanum)

    One or two students may work on this topic per term.

  • Modelling of Nanooptical Structures with Rigorous Numerical Methods

    Goals and context

    The strong coupling of light to quantum systems relies on the confinement of electromagnetic fields to sub-wavelength 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 sub-wavelength range, "rigorous" methods are needed, which solve Maxwell´s equations without any approximation. Different approaches have become popular and important for certain classes of nanophotonic structures (micro and nano cavities, metasurfaces, nanoantennas).

    Methods

    The students will implement and use a rigorous numerical numerical method (FMM, FDTD, FEM, or BPM) 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 high-performance 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 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)

    Organization

    Person in charge: Prof. Dr. Thomas Pertsch

    Supervisor: Dr. Ángela Barreda and/or Dr. Tobias Vogl

    Place: Abbe Center of Photonics, Computer Pools

    Per term, up to two groups of one or two students may work on the topic.

  • Schrödinger vs. Dirac: Accurate numerical solutions for high-Z ions

    Context

    Most computational methods in atomic and molecular physics as well as quantum chemistry are based today on the hydrogenic atom. Unlike the single-electron Schrödinger equation in a Coulomb potential, however, no analytical solutions can be found for many-electron ions, atoms and molecules, or if external fields and particles are involved. More often than not, therefore, accurate numerical solutions are required in order to describe the excitation or ionization of atoms and molecules.

    This project aims to solve and compare the Schrödinger and Dirac equations for hydrogenic ions. For such ions with high nuclear charge (high-Z), in particular, a relativistic wave equation is required in order to understand their fine-structure and binding. Apart from its single-particle interpretation, moreover, most quantum-electrodynamical (QED) calculations of bound systems are based on Dirac's equation as well. To obtain accurate solutions for these ions, a whole toolbox of numerical methods are known, including finite-differences, basis-set-expansions or discrete-variational representations (DVR) methods.

    This project aims to solve the Schrödinger and Dirac equation for a point-like as well as extended nucleus. These solutions are to be analyzed and compared to each other with regard to their energies, degeneracy and shape of the wave functions.

    Goals of the project

    • Recall the analytical and numerical solution of the (radial) Schrödinger equa-tion in a Coulomb potential, i.e. the hydrogen atom.
    • Explore the SO3 rotational symmetry of atoms and ions.
    • Work with the coupling of orbital and spin angular momenta as it naturally arise sfrom Dirac's equation.
    • Develop a program for the setup and diagonalization of the Hamiltonian matrix to obtain accurate solutions of the low-lying bound states.
    • Understand basic numerical integration techniques (Gauss-Legende, Gauss-Laguerre, …) and how they are related to the interpolation.
    • Learn about Lagrange interpolation formulae.
    • Optional: Solve the equations above for an extented nucleus (homogeneous charge sphere, Fermi distribution, ...)

    Prerequisites:

    • basic knowledge of quantum mechanics
    • programming skills (Python, Julia, C)

    Contact:

    Supervision:  Prof. Stephan Fritzsche, Theoretisch-Physikalisches Institut

    Where: Theoretisch-Physikalisches Institut & Helmholtz-Institut Jena, Fröbelstieg 3.

    Per term, one or two students may work on the project

  • Computer experiment: Quantum tomography of photonic qubits (not available in WS 23/24)

    Context

    Quantum tomography has been widely applied in quantum computing and quantum information theory during recent years to determine the state vector (density matrix) of simple quantum systems. In contrast to a single quantum measurement, which randomly leads to one of the eigenvalues (outcomes) and eigenvectors (post-measurement states) of an observable (hermitian operator), quantum tomography aims to reconstruct the full quantum state as it is assigned to the system prior to the measurement.

    To reconstruct the (initially) unknown quantum state of a system, large ensembles of identical prepared quantum systems (states) are typically required. Moreover, a tomographically com-plete set of measurements need to be chosen to determine a quantum state uniquely. Mathe-matically, this means that this set of measurement operators need to form a valid (operator) basis for the Hilbert space of the given system. In this project, we wish to analyze the polarization state of single photons as well as of photon pairs, similar as generated in the spontaneous parametric down conversion process and as applied for EPR type experiment.

    This project aims to reconstruct the density matrices of single- and two-photon quantum states  from a simulated measurement statistics. Different methods from linear algebra and the least-square-optimization should be explored and compared to each other.

    Goals of the project

    • Recall and understand the formalism of the density matrix and quantum measurements (measurement operators) in order to obtain and analyze the outcome of any (computer) experiment.
    • Explore the close relation between the polarization state of photons and spin-1/2 particles (like electrons, protons, …).
    • Work with the (generalized) Pauli matrices and the correlation tensor of few-qubit systems.
    • Understand to role of (quantum-) tomographic methods for analyzing simple quantum gates.
    • Design a program code for the reconstruction of the density matrix from the generated outcomes (measurement statistics).
    • Explore and determine the scaling of the required effort for n-qubit systems.
    • Optional extensions: What means and how can one perform quantum process tomography?

    Prerequisites:

    • basic knowledge of quantum mechanics
    • programming skills (Python, Julia, C)

    Contact:

    Supervision:  Prof. Stephan Fritzsche, Theoretisch-Physikalisches Institut

    Where: Theoretisch-Physikalisches Institut & Helmholtz-Institut Jena, Fröbelstieg 3.

    Per term, one or two students may work on the project

  • Hydrostatic Models of Planet Interiors and Atmospheres (not available in WS 23/24)

    Goals and context:

    Most of what we know about the internal structure of planets in the solar system ( and elsewhere) is based on observations of their external properties - and on models. Such models need to cover an extreme range of physical conditions and states, from low-pressure gas to high-pressure liquids and solids, including "exotic" material succh as liquid hydrogen. In this project, simple models of planet interiors and atmospheres are constructed and tested against more refined models and observational constraints. Possible examples for specific goals include:

    • test of the limits of simple models (When do they work? When and how do they fail?)
    • implementaion and test of more advanced analytic approximations of equations of state or tabulated material properties (When und where are they useful?)
    • construction of more complex models (What role do internal enegy souces and the temperature gradient play?)
    • etc.

    Methods:

     Available analytic and numerical prescriptions for hydrostatic equilibrium, equations of state, and heat transfer are used to construct a new model or modify an existing one. Additional material properties and constraints are extracted from the literature. Possible languages for programming (and in most cases also visualization of the results) include C++, Wolfram Mathematica, Phyton, Mathlab.

    Instructor:      Dr. Torsten Löhne

    Venue:          online and/or 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. Supervision is possible in English and German.

  • Navier-Stokes-Equations (not available in WS 23/24)

    Context and goals

    Computational Fluid Dynamics (CFD) is a central part of computational physics and has been a driver for the development of modern numerical methods. It involves solving flow mechanical problems that cannot be solved analytically and are expensive to study experimentally by integrating generally nonlinear, partial differential equations.

    In this project, the students will apply numerical methods to solve the Navier-Stokes-Equations for the case of an incompressible fluid to study flow within a cavity and flow around obstacles.

    Methods

    Timestepping schemes for integration of hyperbolic equations as well as a relaxation scheme for solving elliptic equations will be employed to solve the Navier-Stokes-Equations numerically on a staggered grid in two dimensions. The stability and convergence behavior of these schemes will be examinated.

    The students will use C/C++, Python or Matlab to implement these methods.

    Prerequisites

    • Basic knowledge of partial differential equations
    • Basic knowledge of numerical methods
    • Familiarity with at least one of the suggested programming languages

    Organisation

    Person in charge: Prof. Dr. Bernd Brügmann

    Supervision: Sarah Renkhoff

    Place:  Abbeanum, Fröbelstieg 1 or PAF Computerpool

    One or two students may work on this project

  • Quantum Simulation of Particle Tunneling (not available in WS 23/24)

    Goals and Context

    The tunneling of a wave through a potential barrier is one of the fundamental experiments in quantum physics and arguably one of the most studied effects thereof. It has contributed greatly to our understand of the quantum world and is, as such, an ideal experiment to test new simulation methods. The one in question for this project are quantum computers. These utilize interference as a resource for algorithmic problems and are thus exceptionally well-suited to study interference phenomena with almost exponential speedup in scaling over their classical counterparts. Based on a newly developed method to efficiently solve wave equations in QCs we would like to re-investigate quantum tunneling both as a test-case of the method and also as a benchmark on real state-of-the-art quantum computers.

    Methods

    The students will use a newly developed method to solve Schrödinger's Equation on a Quantum Computer and implement efficient ways to model various types of potential barriers. They will then analyze the statistical nature of the Quantum Simulation to derive precision boundaries for observables. The programming is done with Python and involves the execution of code on a real quantum computer, accessed via the QISKIT interface.

    Prerequisites

    • Basic knowledge of partial differential equations
    • Basic knowledge of programming (Python)
    • Basic knowledge of Quantum Physics

    Organization

    Person in charge: Dr. Falk Eilenberger

    Supervisor: Dr. Falk Eilenberger / Siavash Davani

    Place: Abbe Center of Photonics, Computer Pools

    Per term, up to two groups of one or two students may work on the topic.

Astronomy

  • Detection and Observation of Runaway Stars

    Contents and learning objectives

    Runaway stars are young, hot, massive or intermediate-mass stars showing a peculiarly high velocity with respect to the host cluster or OB association. They are moving away from their birth place, while the majority of others remain in their birth cluster. The high velocity nature of runaway stars is explained by two independent mechanisms:

    1. Dynamical ejection scenario (DES) proposes that the stars are ejected by gravitational interaction within the dense cores of the young clusters.
    2. Binary supernova scenario (BSS) brings an alternative explanation that the star is ejected by its orbital velocity due to the supernova of the binary companion.

    Kinematic studies and observations of the young clusters has proven that the DES is working. On the other hand, high space velocities of isolated neutron stars imply that BSS is also viable. However, the star HD37424 is the only BSS runaway star which has been proven by observations. Finding BSS runaway stars provide us with great information on the supernova, supernova remnants (SNR) and neutron stars. The type of supernova, distance, age and all dependent parameters of the supernova remnant, the mass of the progenitor star and the kick given to the neutron star can be found. Therefore, exploring BSS runaways is now an important task in astrophysics. The BSS runaways can be found inside the supernova remnants (e.g. Spaghetti Nebula). The astrometry by the Gaia Satellite gives us precise distances and transverse motion vectors of the stars. A star having a significantly higher transverse velocity w.r.t the galactic neighborhood and moving away from an SNR is a potential candidate. These candidates can be detected through public astrometry and photometry data and be confirmed by spectroscopic observations. For bright stars (V<11 mag), the observations can be performed at the University Observatory in Grosschwabhausen. The project aims to teach students using astronomical catalogs, stellar kinematics, observations and data reduction and analysis.

    Tasks

    •   Selection of stars within a certain position and distance range
    •   Calculating the peculiar transverse velocity from proper motion of the stars
    •   Age estimates and tracing back the stellar motion in time
    •   Temperature and evolutionary stage estimation from photometry
    •   Spectroscopic observations of good candidates in Grosschwabhausen
    •   Data reduction and analysis

    Supervision: 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 in one group (of 2 students).

  • Gamma-Ray Burst Afterglows
    illustration of the Swift satellite (top left); host galaxy of GRB 171205A and associated GRB-SN 2017iuk (top right); light curve of GRB 921003 (bottom left); GRB-afterglow light curve of GRB 150413A (bottom right)
    illustration of the Swift satellite (top left); host galaxy of GRB 171205A and associated GRB-SN 2017iuk (top right); light curve of GRB 921003 (bottom left); GRB-afterglow light curve of GRB 150413A (bottom right)
    Foto: Sebastian Schmidl

    Content

    From the discovery of the first Gamma-Ray 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 gamma-rays: ~1051 - 1053 erg) has drastically expanded. We know today that these short-time gamma-ray 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 gamma-ray burst itself can be described within the fireball model by the collision of multiple shells traveling at high-relativistic velocities. After the burst, one can observe the afterglow of the GRB (from X-Ray 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 F-Pranktikum (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. 

  • Historische Beobachtungen als Erkenntnisschlüssel für aktuelle astrophysikalische Fragen (not available in WS 23/24)

    Lernziele und Inhalte:

    Supernovae, Novae: Im Laufe der letzten zwei Jahrtausende sind bis 1604 knapp zehn Supernova-Explosionen in unserer Galaxie von den Menschen beobachtet und notiert worden, meist Kernkollaps-Supernovae massereicher Sterne (Typ II), seltener auch thermonukleare Supernovae (Typ Ia), also explodierende Weisse Zwerge. Desgleichen wurden ggf. auch einige Novae beobachtet, also nicht-endgültige, kleinere Explosionen von Weissen Zwergen. Nova oder Supernova wurden als neuer Stern (Latein: nova stella) erkannt und bemerkt. Aufzeichnungen von Zeitpunkt, Position, Helligkeit und Farbe liegen aus Europa, Arabien und Fernost vor. Während der neue helle Stern einige Monate sichtbar blieb, kann man heute weiterhin den Supernova-Überrest bzw. die Nova-Schale (Gase) und bei Kernkollaps-Supernovae den Neutronenstern beobachten. Wichtig für die aktuelle Astrophysik sind dabei u.a., dass durch die historische Beobachtung das exakte Alter der Überreste und Neutronensterne bekannt sind, was sonst mit astrophysikalischen Methoden weniger genau bestimmt werden kann.

    Erdrotation: Ferner wurden zahlreiche Sonnen- und Mondfinsternisse beobachtet und dabei oft Ort und Zeitpunkt genau angegeben. Die Orbits von Mond um Erde und Erde um Sonne kann man heute sehr genau zurückberechnen, also Orte und Zeiten von Finsternissen berechnen. Aus Abweichungen solcher Berichte und der Rückrechnung schliesst man dann auf Änderungen in der Erdrotation durch die Verlagerung des Drehmoments seit dem Ende der letzten Eiszeit.

    Kometenorbits: Es wurden auch viele Kometen beobachtet und deren Positionen notiert. Daraus kann man heute deren Orbits bestimmen etc.

    In diesem Projekt sollen zunächst die Berichte der chinesischen Jin-Dynastie (3./4. Jahrhundert) bearbeitet werden, die in englischer Übersetzung vorliegen.

    Man soll die historischen Beobachtungen prüfen und verstehen, um sie dann besser für aktuelle Fragen der Astrophysik einsetzen zu können, z.B. die beschriebenen Sonnen- und Mondfinsternisse nachrechnen. Alternativ oder zusätzlich könnte man die Vollständigkeit historischer Aufzeichnungen bestimmen, indem man die Vollständigkeit von berechenbaren Himmelsereignissen bestimmt, wie z.B. Mond- und Sonnenfinsternisse sowie nahe Planetenkonjunktionen, die ebenfalls aufgezeichnet wurden.

    Technik:

    Literaturstudie zu historischen Aufzeichnungen; Bestimmung des Datums der Beobachtung; Identifizierung der genannten Sterne, Planeten etc., Überprüfung der Berichte durch Rückberechnung der Beobachtung. Vorarbeiten liegen vor, sind aber unvollständig, neue Ergebnisse sind zu erwarten.

    Betreuer: Prof. Dr. Ralph Neuhäuser

    Ort: Astrophysikalisches Institut, Schillergäßchen 2, Jena

    Jedes Teilprojekt kann von 1 oder 3 Studierenden bearbeitet werden. Die konkrete Aufgabenstellung wird je nach Teilprojekt etwas angepasst. Mögliche Projekte: Nachberechnung der Mondfinsternisse, Nachberechung der Sonnenfinsternisse, Vollständigkeit der Finsternisse (d.h. unter welchen Bedingungen waren sie detektierbar?), Häufigkeit bzw. Vollständigkeit von Kometen, Überprüfung der Berichte von Venus-Sichtungen am Tage, Nachberechnung von Planetenkonjunktionen, etc.

  • Observation of Open Clusters (not available in WS 23/24)

    Contents and learning objectives

    Stars are mostly born in open clusters and spend a significant part of their lives as a member 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 cluster members share similar distance, age, metallicity, extinction, and velocity; hence they are the key objects in stellar evolution studies. 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 color-magnitude (Hertzsprung-Russell) diagram of the cluster members indicates the age, metallicity and the extinction. The most massive and hottest stars of the cluster evolve faster, move away from the main sequence in the color-magnitude diagram and become cooler giants and/or supergiants. The position of the turn-off 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 color-magnitude 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 down the uncertainty of theoretical isochrones. 

    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.

    Tasks

    • Selection of cluster members regarding their positional and kinematic properties.
    • Setting the color-magnitude diagram using optical and near-infrared 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 and the cluster age by the isochrone fitting.

    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 2 students.