Research Phase and Master's Thesis in the Physics programs

An essential step for implementation of quantum computing architectures is an efficient readout of qubits. In the field of superconducting quantum circuits, this is typically realized by dispersively coupling a superconducting qubit to a microwave resonator. Then, the frequency of the resonator depends on the state of the qubit. The former can be extracted by probing the resonator with a coherent  tone. However, efficiency of this readout approach is fundamentally limited by quantum  laws. The corresponding threshold is commonly known as the standard quantum limit and bounds quantum efficiency of the readout process by 50%. Nevertheless, recent investigations have shown that it is possible to circumvent this limit and reach quantum efficiency of the qubit readout of 100% by exploiting broadband readout signal combined with Josephson parametric amplifiers.

The goal of this Master project is to build a proof-of-principle experimental setup and perform microwave cryogenic measurements on a superconducting transmon qubit in the broadband regime in order to demonstrate violation of the standard quantum limit in the dispersive readout.

Scientific motivation: 

Does there exist an undiscovered type of neutrino, a so-called sterile neutrino? Could this particle be the Dark Matter? These are among the most topical open questions in Astroparticle physics at the moment. 

The aim of the TRISTAN project, is to develop a novel multi-pixel Silicon Drift Detector system to upgrade the KATRIN apparatus. This upgrade would allow the  KATRIN experiment to search for this hypothetical new particle. 

Thesis Topic:

The topic of this Thesis project is the characterization of the next-generation TRISTAN prototype detectors. The goal of this project is a detailed understanding of the detector response to photons and electrons. For this purpose you will perform measurements with x-ray calibration sources and with an electron microscope at the Semiconductor Laboratory of the Max Planck society in Munich. For this purpose a dedicated test stand has to be designed and fabricated. The measurements and data analysis will be complemented with detailed Monte Carlo simulations of the particle interactions in the detector and the signal generation. 

You will gain & learn:

• Learn about astroparticle physics 

• Detailed understanding of semiconductor detector technology

• Expertise in experimental hardware work 

• Programming in Python and C++

• Work in a fun team with lots of social events

Scientific motivation:

The structure of astrophysical compact objects e.g. black hole binaries (BHB) can not be resolved with optical methods. Therefore one has to use other methods to get informations on processes in and around these systems. By measuring the polarization of the emitted hard X-rays it is possible to draw conclusions on their production mechanism and the geometrical structure of BHBs. The CubeSat project ComPol (Compton Polarimeter) aims at measuring spectrum and polarization of the BHB Cygnus X-1 in the hard X-ray range (20 - 2000 keV).

Since it will be a CubeSat based mission, the whole system has to be very compact to fit in the satellites volume (~10x10x30cm³). The small detector area together with strong weight limitations makes it ambitious to achieve a good sensitivity. Besides lab tests simulations are needed to get the best out if it.

Thesis Topics:

1. Simulation based design study for ComPol, a Compton telescope inside a Nano-satellite

2. Characterizing and testing components of the first ComPol prototype

You will gain & learn:

• Learn about astroparticle physics

• Understand the working principle of Compton telescopes

• Detailed understanding of semiconductor detector technology

• Expertise in experimental hardware work

• Knowledge of Monte Carlo particle simulation with Geant4

• Programming in Python and C++

• Work in a fun team with lots of social events

The CRESST (Cryogenic Rare-Event Search with Superconducting Thermometers) experiment operated at the Gran Sasso underground laboratory employs highly sensitive cryogenic detectors to the search for signals of the elusive dark matter particles, a main ingredient of the Universe whose nature is still unknown. 

The energy thresholds reached in CRESST-III are the lowest in the field, making CRESST the most sensitive experiment to light dark matter. Optimisation of the tungsten thin-film thermometers and of the techniques for data analysis promise still improvement in energy threshold, which could significantly boost the physics reach of the experiment.

Scientific topics

A student can contribute to:

- design, production and prototyping of new CRESST detectors in Munich 

- development of high purity crystals 

- development of new software tools for data analysis

- dark matter data analysis

and, if interested, can participate in the operation of the main experiment at Gran Sasso. 

Thesis can be carried out at the Chair for astroparticle physics of the Physics Department and/or at the Max-Planck-Institute for Physics (MPP). Supervision at the Physics Deptartment by Prof. Schönert / Dr. Strauss and at the MPP by Prof. Schönert /  Dr. Federica Petricca. Please contact schoenert@ph.tum.de, raimund.strauss@ph.tum.de and petricca@mpp.mpg.de for further information. 

Scientific motivation: 

What is the mass of the neutrino? This is one of the most fundamental open questions in Astroparticle Physics today. We know from neutrino oscillations that neutrinos must have a mass, but its actual value is still unknown. The knowledge of the neutrino mass would be an important key to understand the formation of structures in the early universe and it could help to shed light on the fundamental origin of masses.

The Karlsruhe Tritium Neutrino (KATRIN) experiment is a direct neutrino mass experiment, which is designed to determine the neutrino mass via a precise measurement of the tritium beta decay spectrum. KATRIN just started data taking in April 2019. The goal is to reach a sensitivity to the neutrino mass of 200 meV after 3 years of data taking. So, right now is the perfect moment to join the experiment!

Thesis Topic: In this Thesis project you participate in the analysis of the KATRIN data. You will analyze new data sets, acquired in the near future, which will provide unprecedented sensitivity to the neutrino mass. Besides using existing techniques we also focus on developing novel analysis tools based on Bayesian techniques and neural networks. Finally, you will gain a deep understanding of the experiments, as systematic uncertainties in the theoretical description of the measured beta-decay spectrum are of key relevance to achieve the desired sensitivity. 

You will gain & learn: 

• Participate in world-leading experiment to directly determine the neutrino mass

• Learn about astroparticle physics 

• In-depth knowledge on data analysis

• Programming in C++ and Python

• Work in a fun team with lots of social events

Motivation:

The observation of neutrinoless double beta (0𝜈ββ) decay would establish the Majorana nature of neutrinos and explicitly show that lepton number conservation is violated. In their search for the rare decay in the isotope Ge-76, the GERDA and Majorana Demonstrator experiments have achieved the lowest backgrounds and best energy resolutions of any 0𝜈ββ decay experiment. Building on the successful results of these experiments, the Large Enriched Germanium Experiment for Neutrinoless Double Beta Decay (LEGEND) collaboration aims to develop a phased 0𝜈ββ decay experimental program. The first phase of LEGEND, a 200 kg measurement utilizing the existing GERDA infrastructure at LNGS in Italy, is expected to start in 2021. Be part of this amazing collaboration with about 200 scientists from all over the world.

Thesis topics:

1. Development and characterization of ASIC-based readout electronics for Germanium detectors (with possibility of research stay at Berkeley lab)

2. Analysis of first LEGEND data (e.g. focus on optimization of energy resolution)

3. Pulse shape simulations (e.g. investigation of impact of diffusion and self-repulsion)

Technical skills and scientific environment:

• Data analysis methods in experimental physics, C++ and Python programming

• Electronics and cryogenics (liquid Argon & Nitrogen)

• Astroparticle physics

• Scientific writing and presentation of scientific results

Scientific supervision:

• Prof. Dr. Susanne Mertens

• Dr. Michael Willers (Postdoc)

Scientific motivation: 

Does there exist an undiscovered type of neutrino, a so-called sterile neutrino? Could this particle be the Dark Matter? These are among the most topical open questions in Astroparticle physics at the moment. 

The aim of the TRISTAN project, is to develop a novel multi-pixel Silicon Drift Detector system to upgrade the KATRIN apparatus. This upgrade would allow the  KATRIN experiment to search for this hypothetical new particle. 

Thesis Topic:

To search for keV sterile neutrinos in the differential energy spectrum of tritium a sophisticated model is required, which will be the main aspect of this Thesis topic. You will develop and extend the existing model used in the KATRIN experiment for the neutrino mass measurement, to suite the keV sterile neutrino search. A key aspect of this investigation is the understanding of systematic uncertainties and their impact on the final sensitivity of the final TRISTAN experiment. Additionally, already now we can extract an differential energy spectrum from the ongoing measurements through the Forward Beam Monitor, where you can test your model and may extend the current limits for keV sterile neutrinos.

You will gain & learn:

• Learn about astroparticle physics 

• In-depth knowledge on data analysis

• Programming in Python and C++

• Work in a fun team with lots of social events

Modern quantum circuits allow to study strong light-matter interaction in a variety of systems. This so-called strong-coupling regime is key for many aspects of quantum information processing. This project focusses on strong coupling between a paramagnetic electron spin ensemble and a superconducting microwave resonator. Strong coupling is an established phenomenon in this system. However, many aspects regarding the dynamics of this coupled system as well as the non-linear response properties are not fully understood, yet, and we will address these aspects within this project. For this project, we will use superconducting microwave resonators based on NbTiN and spin paramagnetic spin ensembles of phosphorous donors and erbium centers in silicon.

We are looking for a highly motivated master student joining this project. Within your thesis, you will address questions regarding the dynamic response of a strongly coupled system based on a paramagnetic spin ensemble and a microwave resonator. In this context, you will fabricate and optimize microwave resonators and operate them at cryogenic temperatures. In addition, you will use complex microwave pulses, to control the coupled system and experimentally investigate its dynamical response. Within the project, you will learn how to fabricate superconducting microwave resonators in our in-house cleanroom and how to synthesize microwave pulses using arbitrary waveform generators

The project deals with the development of a miniature superconducting polarization sensitive slow neutron detector. As a completely novel idea, the device has a variety of future applications, among those a future next-generation experiment to measure the electric dipole moment of the neutron (EDM), which would through this development gain orders of magnitude in sensitivity. The EDM measurement in turn is key for the explanation of the excess of matter vs. antimatter in the Universe, making our small-scale R&D project potentially highly interesting. If you like this project, please dont hesitate to contact Roman Gernhäuser or Peter Fierlinger

Die Detektorentwicklung der nächsten Jahre wird sich auf den 100-TeV-Hadroncollider, das nächste große Zukunftsprojekt in der experimentellen Teilchenphysik konzentrieren. Für das Myonsystem der Detektoren
an diesem Collider werden Myonkammern benötigt, die eine hohe Myonnachweiseffizienz und Ortauflösung selbst bei hohem Gammastrahlungsuntergrund aufweisen. sMDT-Kammern,
das sind Kammern mit zylindrischen Driftrohren mit 15 mm Durchmesser, scheinen hierfür besonders gut geeignet. Allerdings muss ihre bereits gute Hochratenfähigkeit verbessert werden. Zwei sich ergänzende Ansätze werden hierbei verfolgt. Zum einen kann man die Ortsauflösung und Myonnachweiseffizienz bei hohem Raten durch eine hierfür angepasste Elektronik erhöhen. Zum anderen eröffnen neue Zeitdigitalwandler mit Pikosekundenauflösung die Möglichkeit durch die Auslese der Driftrohre an beiden Enden, den Ort des Teilchendurchgangs in allen drei Raumkoordinaten zu messen. Durch geschickte Auslegung der
Ausleseelektronik können diese Myonkammern sogar selbsttriggernd betrieben werden.

You will develop novel integration algorithms in high-dimensional spaces.  Possibilities include various forms of importance sampling algorithms and the further development of the Adaptive Harmonic Mean Integration algorithm using differently chosen volumes for integration.  Test problems will be chosen from physics projects to validate the algorithm.  Good programming skills and knowledge of linear algebra are a pre-requisite for the project.

This project will explore the use of latest hybrid-pixel photon-counting detectors for improving the image quality in 2D (panoramic) dental imaging applications. More specifically, the project aims at developing advanced dual-energy/ spectral artefact reduction algorithms and their experimental demonstration of their applicability in preclinical experiments. The project will be carried out in close collaboration with an industrial collaboration partner in the Munich area.

Character of thesis work: experimental physics (50%) & image processing (50%)

For more information, please contact: Thorsten Sellerer (thorsten.sellerer@tum.de), Franz Pfeiffer (franz.pfeiffer@tum.de)

In this work, you will manufacture your own printed perovskite solar cells and build a new setup for current-voltage measurements of the illuminated solar cells to determine their efficiency.

Next-generation perovskite solar cells show very high efficiencies competitive to silicon solar cells and have the potential to revolutionize photovoltaics in the near future. Their heart is a thin-film absorber that can be easily deposited onto glass or flexible substrate using a slot-die printer.  You will build solar cells with printed perovskite absorber layers, that are compatible with commercialization. Our group has long-standing experience in perovskite fabrication and printing deposition that you can rely on during your work in our group. For characterization, we have the possibility to conduct X-ray scattering for structural analysis and SEM measurements for real-space imaging, among others.

However, the key method of characterizing solar cells is to measure the diode-like current-voltage-behavior of the cell under well-known laboratory illumination. From this measurement, the most important performance parameters such as the efficiency, current characteristics, and internal resistances of your cells can be extracted. In our labs, we already have such a device, but it does not allow measuring our solar cells in inert atmosphere. In this work, you will build a new setup that enables these measurements inside an inert gas atmosphere. The basic concept is already set up, I would be happy if you wish to learn more about this. Further tasks will include strategic planning of the individual components, drawing parts in CAD, guiding our workshop in constructing the parts, and the final assembly of the setup. You will test the setup by characterizing your printed perovskite cells and correlate the findings to your chosen experimental parameters.

Quantum experiments often require fast and versatile data processing which allows for a quantum feedback operation. This approach opens the road to many fascinating experiments such as quantum teleportation, entanglement purification,  quantum error correction, among others. Here, we would like to develop a specific measurement and feedback setup, based on a field programmable gate array (FPGA), for experiments with propagating quantum microwaves.

The main goal is to program and experimentally test a specific image for an FPGA  which would allow for acquisition of microwave signals and feedback generation over few hundred of nanoseconds. This timescale is the prerequisite for exploiting quantum correlations effects for quantum communication and cryptography protocols with propagating squeezed microwaves which are conducted in our lab. This project will offer a deep insight into the state‑of‑the‑art FPGA devices, microwave measurements, and cryogenic experiments with superconductors.

The aim of this Master thesis is to explore different modes of cell wall growth, which is locally controlled by enzymes but has a global effect on the shape of the cell. Which schemes of enzymatic action permit stably growing cell shapes? And which ones can mimick the observed growth behavior of different bacterial species? These fundamental questions are surpisingly largely open, partially due to the difficulty of experimentally determining which local properties of the cell wall affect the enzymatic activity. In light of this experimental barrier, conceptual theoretical models can classify different plausible schemes by their large-scale behavior, which is more easily observed experimentally. This thesis will combine simulations of stochastic models for growing shapes with simple analytical toy models to address some of the open questions.

Next generation organic solar cells are solar cells beyond the silicon type photovoltaic devices. Organic solar cells have reached efficiencies in the champion solar cells well above 15%. Key element of such solar cells is the highly designed active layer, which transfers light into separated charge carriers. Aim of this experimental project is the preparation and full characterization of an active layer for high performance organic photovoltaic devices to further understand the fundamental correlation between morphology and solar cell performance. In this work a novel efficiency record-setting system will be investigated regarding the influence of an additional third component, in our case, either solvent additive or polymer. The project will involve a literature review, sample preparation, photovoltaic device fabrication and photoluminescent measurements. The focus is the usage of advanced scattering techniques for the determination of structural length scales of the active layer in the solar cell.

The smaller a device is, the higher its resonance frequency becomes. For our future quantum optomechanics experiments we will be working with mechanical resonators that operate at GHz frequencies and simultaneously couple strongly to light. Using mechanical and optical band structure calculations, you will design, make, and measure phononic and photonic cavities. The project involves nanofabrication in the cleanroom, as well as using the extreme sensitivity offered by on-chip optomechanics. We are aiming for devices made from silicon nitride, which has a lot of tensile stress in it. For micromechanical structures this material gives much better mechanical properties compared to, for example, silicon devices. An important aspect of the project is to understand if this is also true for the high frequency devices.

Hybrid materials combining nontrivial conducting and magnetic properties are of high current interest, especially in the context of potential spintronic applications. The organic charge transfer salts (BETS)₂FeX₄ with X = Cl, Br provide perfect natural structures of conducting and magnetic layers alternating on the single-molecule level. Our project is aimed at a quantitative study of the interaction between the two subsystems and of the role of the subtle structural modifications in this family. To this end, high-precision measurements of quantum oscillations in the electrical resistance and magnetization will be carried out on single crystals of these compounds under strong magnetic fields. The results will be analyzed in terms of electronic correlation and magnetic interaction effects.

Physics: Correlated electronic systems; magnetic ordering and superconductivity; magnetic quantum oscillations.

Techniques: Strong magnetic fields; magnetotransport; magnetic torque; cryogenic (liquid ⁴He and ³He) techniques.

Contact person:  Mark Kartsovnik (mark.kartsovnik@wmi.badw.de)

GRAVITY [1] is a novel instrument which combines the light of four telescope at the ESO VLTI observatory. Employing the techniques of fringe tracking and phase referencing, it allows to measure complex visibilities at IR wavelengths and for imaging at unprecedented angular resolution in this part of the electromagnetic spectrum. Our group's particular interest is the use of GRAVITY for high-precision studies of the galactic center, where it has enabled several breakthrough discoveries [2]. To cope with the data complexity, we are developing a novel imaging code, based on the framework of Information Field Theory [3], which is written in python and based on the NIFTy [4] package. The goal of this master project is to investigate instrumental systematics, their impact on image reconstruction and to implement a model or correction. Eventually, a better description of the instrument will push the sensitivity towards fainter objects and allow to study Sagittarius A*, the radio source associated with the massive black hole in the center of the Milky Way, in greater detail.

Contact: Dr. Julia Stadler <jstadler@mpe.mpg.de>

[1] GRAVITY collaboration, "First light for GRAVITY: Phase referencing optical interferometry for the Very Large Telescope Interferometer", Astronomy & Astrophysics, Volume 602, id.A94, 23 pp.

[2] GRAVITY collaboration, "GRAVITY and the Galactic Center", ESO Messenger Vol. 178, 2019

[3] T. Enßlin, "Information Theory: Information Theory for Fields", Annalen der Physik, vol. 531, issue 3, p. 1970017

[4] P. Arras et al., " NIFTy5: Numerical Information Field Theory v5", Astrophysics Source Code Library, record ascl:1903.008

Bose-Hubbard systems offer an intriguing opportunity of studying quantum driven-dissipative dynamics. Nowadays, these systems can be conveniently implemented by combining superconducting resonators with Josephson junctions. In order to successfully measure nonclassical effects in these systems, such as generation of antibunched light, one needs to accurately quantify their respective frequency range and nonlinearity strength. This goal can be achieved by cryogenic microwave measurements of a Bose-Hubbard dimer with superconducting quantum circuits and numerical modelling of the respective Hamiltonian. These two steps comprise the main body of the current master project. The successful project will potentially lead to a development of robust single-photon microwave sources and further exploration of quantum matter in the form of networks of nonlinear superconducting resonators.

Even though we know that neutrinos must have masses, we do not know yet which mechanism generates them. One possibility is that they are their own antiparticles, being of “Majorana” type. An experimental hint for this would be the measurement of lepton number violating interactions e.g. at the LHC, neutrinoless double beta decay or meson decays. In an effective field theory, we want to study the complemenatry of these interactions and their experimental prospects in more detail.

In this project, we aim to fabricate and investigate novel organic-inorganic hybrid materials for thermoelectric applications. The goal is to realize efficient low temperature (T < 100°C) thermoelectric thin films and coatings which can contribute for example to energy efficient buildings. By combining nanostructured inorganic materials with conducting polymers a novel approach for this class of materials shall be realized. Possible inorganic nanomaterial components include Silicon nanocrystals (either undoped, n-type or p-type doped) as well as other nanoparticles. Different polymer materials such as the polymer blends of conjugated polymers, which can be tuned in conductivity and in its nanostructure, shall be used as the organic partner in our hybrid approach.

Hybrid solar cells combine an inorganic and an organic component into a photovoltaic cell. They combine the advantages of inorganic materials (e.g. metal oxides: TiO2 or GeO) such as high charge carrier mobility and very high stability with those of organic materials (e.g. conducting polymers: PTB7) such as cost-effectiveness and flexibility. In comparison with standard silicon solar cells, the hybrid solar cells can be easily manufactured and can allow for alternative processing techniques as for example spray-coating and printing. In contrast to dye sensitized solar cells (DSSCs), hybrid solar cell devices contain no dye as active components and consequently problems such as photo-bleaching are mitigated. Moreover, all materials in the hybrid solar cells are solid and thus no sealing to protect against leakage of aggressive solvents such as in DSSCs is required. Regarding application, the hybrid solar cells are more environmentally friendly. Compared to organic solar cells, which are composed purely out of organic components, hybrid solar cells are expected to have higher lifetime stability. In particular, a degradation of the morphology, which is one pathway in organic solar cell degradation, cannot happen in the hybrid solar cells. The inorganic component acts as a corset to the morphology and prevents structural changes. Despite all these advantages of hybrid solar cells, so far most research on alternative solar cells beyond the silicon solar cells, has been focused on DSSCs and organic solar cells. hybrid solar cells have gained much less attention and therefore have a high undiscovered potential, which will be investigated in the present thesis based on novel pathways.

This project will explore the use of latest hybrid-pixel photon-counting detectors for improving the diagnostic accuracy of chest X-ray examinations. More specifically, this work will use dedicated phantoms for assessing the potential clinical benefit of photon-counting-based material decomposition algorithms for better lung cancer and tuberculosis detection. The project will be carried out in close collaboration with the Department of Radiology at the TUM Klinikum Rechts der Isar.

Character of thesis work: experimental physics (50%) & image processing (50%)

For more information, please contact: Thorsten Sellerer (thorsten.sellerer@tum.de), Franz Pfeiffer (franz.pfeiffer@tum.de)

Quantum optics is an extremely powerful approach towards quantum communication, quantum sensing, and quantum computing. In particular, quantum information stored in photons has very low decoherence and can be transmitted over large distances through optical fibers. To date, most experiments in quantum optics use optical tables full with mirrors and beam splitters that all have to be carefully aligned and stabilized. This may be good enough for initial demonstrations, but in order to bring quantum science into the realm of quantum technology, a more scalable approach is required.

With our expertise in making photonic chips using advanced nanofabrication, we are making putting these exciting quantum optics experiments on chips. Here, light is routed via optical waveguides. Furthermore, by bending a waveguide, one gets the equivalent of a free-space mirror; a beam splitter cube becomes a directional coupler and so on. By combining these elements, we can make the building block for e.g. an optical quantum computer. With that, the possibilities are almost unlimited.

For such large-scale optical quantum circuits we also want to incorporate single-photon sources, superconducting single-photon detectors, and optomechanical phase shifters. This all happens on a single chip. Making and characterizing the components is the first step and from there on, you are making more and more complex quantum chips. You will be doing the nanofabrication in the cleanroom, and then use our optical measurement setups to see how each device is performing. Depending on your preference, it may also be possible to add a modelling component to the project.

See http://www.groups.ph.tum.de/en/qtech/openings/ for a detailed description of this project.

Das zytoskelett ist ein aktives Polymernetzwerk innerhalb von jeder eukaryontischen Zelle. Die Aktivität diesesNetzwerks ermöglichen alle lebensnotwendigen Prozesse von Zellen - von der Zellteilung, Zellbewegung bis hin zum Zelltod. Im Rahmender Arbeit sollen einzelne Komponenten in vitro rekonstruiert werden und deren Dynamik quantifiziert werden. Ziel ist es eine Art künstliche Zellen zu bauen, um die biologischen Prozesse besser verstehen zu können. Zum Einsatz kommen eine Reih von hochauflösenden Mikroskopiemethoden, Bildverarbeitung und biochemische Technologien. 

Nanostructuring of thin films has been utilized as a method for light trapping and enhancing the optical path-length of photons within the absorbing material. Structured surfaces utilize geometries to enforce such routes, which are commonly attained by energy, cost-extensive techniques such as lithography, plasmon resonance. Hybrid perovskites are solution processable materials that exhibit efficiencies competitive with the state-of-the-art silicon solar cells, at significantly lower costs. The precursors exhibit colloidal nature, which makes it possible to tune thin film morphologies by controlling the chemical nature of these precursors by harnessing self-assembly behaviour in drying colloidal dispersions.

Mixed hybrid perovskite thin films will be prepared from colloidal solutions. The solution will be characterized by SAXS, DLS, UV-Vis. Interaction of the solution with substrates will be studied by means of contact angle measurements. Thin films prepared from colloidal dispersions will be characterized by XRD, SEM, AFM, UV-Vis. Solar cells will be prepared and characterized for their photovoltaic response.

White smokers are likely the cradle of life. Their pores and tunnels allow for pockets of catalytic sites that fuel reactions at the very origin of life. How do these catalytic sites form and grow with the smoker? You will map out the structure of two-dimensional smoker models generated in William Orsi’s lab at LMU. You will then use your maps to simulate the flow and transport of reactants with the flow through the smoker. Methods: Matlab, Image Analysis, Statistical Physics, Stochastic Processes, Fluid Physics. Prerequisites: Statistical Physics and fascination for the marvels of nature.

Optomechanics provides extremely sensitive methods to measure the displacement of mechanical resonators. However, the forces are much smaller in optomechanics compared to those in nanoelectromechanical systems (NEMS). The goal of the project is to make, and measure opto-electromechanical devices which have strong electrostatic interactions. This includes the electrostatic spring effect where the resonance frequency depends strongly on the applied voltage. The next step is trying to measure the potential by measuring the ringdown of different mechanical modes. The devices will be made using advanced nanofabrication techniques such as electron beam lithography and reactive ion etching.

See http://www.groups.ph.tum.de/en/qtech/openings/ for a detailed description of this project.

More than half of the stars forms in multiple systems. The dynamical interactions between the multiple stars can have a profound influence on the formation and evolution of stars and planets. This, however, is not well understood, especially at the early stages of star formation, due to the difficulty of observing young stars obscured by its surrounding natal cloud. Recent high-resolution ALMA (the Atacama Large Millimeter/submillimeter Array) observations have spatially resolved the emission from complex organic molecules around a very young protostellar binary system [1], also constraining the stellar masses and orbital parameters. The emission from these molecules coincides with features seen in the dust around the binary accretion disks, possibly corresponding to spirals or tightly wound structures. These features are difficult to explain if the emission arises solely due to heating from the forming protostars, the most common scenario used to explain the appearance of warm complex organic molecule emission around protostars. We propose to investigate the role of shocks created by the binary interactions in the production and distribution of molecular tracers at scales from a few up to 100 astronomical units. Gravitational forces from the binary stars can create shocks in the disk surrounding them. Detailed numerical simulations will be needed to investigate the temperature and density structure created by the interaction. This study will shed light on how the binary interactions can influence the chemical inventory in multiple systems at planet formation scales. During this master project, the student will carry out 3D hydrodynamical simulations with the orbital and gas properties observed in the protostellar binary [2]. Detailed thermo-dynamics will be built to investigate the origin of the high temperature and density tracers seen in the gas phase towards this embedded binary system. The student will analyze the spirals or other types of shocks features formed in the simulations, and how it depends on the numerical and physical parameters.

Prerequisites: Basic knowledge in programming (C/C++ and Python will be used).

Contact: Dr. Munan Gong <munan@mpe.mpg.de>, Dr. Maria Jose Maureira <maureira@mpe.mpg.de>, Prof. Dr. Paola Caselli <caselli@mpe.mpg.de>

[1] Maureira et el. 2020, "Orbital and Mass Constraints of the Young Binary System IRAS 16293-2422 A". The Astrophysical Journal 897.

[2] Moody et al. 2019, "Hydrodynamic Torques in Circumbinary Accretion Disks", The Astrophysical Journal 875.

Nach der Entdeckung des Higgsbosons am LHC im Jahre 2012 ist die Untersuchung der Eigenschaften des Higgsbosons in den Vordergrund gerückt. Viele Erweiterungen des Standardmodells sagen kleine Änderungen der Kopplungen des Higgsbosons an die schwachen Eichbosonen voraus. Das Studium der Raten der Produktion des Higgsbosons in Assoziation mit zwei Eichbosonen sowie die Untersuchung der
Winkelverteilungen im Zerfall des Higgsbosons in zwei Z-Bosonen gestatten es, die Art und Größe der Abweichungen der Kopplungen von der Standardmodellvorhersage einzugrenzen.

Titanium dioxide is a semiconductor widely used in solar cells. To harness the energy of the solar spectrum, it is sensitised with dyes which are bound by single or dual tethers. Most commonly these anchors are carboxylate groups, however catecholates and hydroxamates are also reported as convenient and robust alternatives.

With this project we aim to provide a comparative study on the microscopic events that lead the different tethers to guide the adsorption of molecular dyes on model titania surfaces. Scanning tunnelling microscopy under ultra-high vacuum conditions and at a temperature range of 250 to 350 K will be used as a convenient tool to provide real-space information about the adsorption and diffusion of single and dual anchors on single crystal surfaces of titanium dioxide.

Im Rahmen des MADMAX Projektes zur Suche nach dunkler Materie Axionen werden verschiedene
Testaufbauten bei Raumtemperatur und in flüssigem Helium (4 K)
zur Kalibrierung und zur Untersuchung der genauen Signalantwort des
experimentellen Aufbaus betrieben. Es werden Reflektionsdaten Daten
genommen und ausgewertet.

In the frame work of the MADMAX projects several test stands at room tamperature and in liquid helium
for the investigation of the detailled system response and for calibration of the setup are being operated. Reflectivity data will be atken and analyzed.

In 2011, a new solid lithium electrolyte was reported, featuring liquid-like Li-ion conduction in a crystalline solid matrix. The ultrafast room temperature transport of tetragonal Li10GeP2S12 (LGPS) with a conductivity of several mS/cm exceeds the values of most crystalline Li conductors by one order of magnitude. Accordingly, there has been a strong search in realizing LGPS-type materials based on the homologous elements Si and Sn. LXPS (X=Ge,Sn,Si) electrolytes appear in a tetragonal and orthorhombic modification. While the orthorhombic phase is an undesired inpurity in the LGPS electrolyte, orthorhombic LSPS leads to an enhancement of the conductivity. A possible explanation of the increased conductivity,
is an interplay of orthorombic and tetragonal LSPS, which distorts tetragonal LSPS. This distortion may lead to a favorable opening of Li-channels. The aim of this work is to investigate the effect of distortion on the materials conductivity for tetragonal LSPS. To do so a machine-learned force-field will be provided. The project will start with the construction of distorted LSPS structures and will then focus on Molecular Dynamics (MD) calculations for appropriate LSPS ensembles at finite temperatures. Finally, the conductivities will be calculated via the Nernst-Einstein relation.

The combination of quantum mechanical calculations and machine-learning techniques has led to massive advances in the high-throughput computational screening of materials and molecules. Here, it is frequently stated that training data obtained from quantum mechanical simulations (e.g. using density functional theory) is 'noise-free', because the calculations can be numerically converged to very high precision. However, this assumes that the self-consistent algorithm used to calculate the Kohn-Sham determinant always converges to the correct ground-state solution, which is by no means guaranteed. The goal of this project is to quantify the noise introduced into DFT data by different choices of intital guess and convergence acceleration. To this end, the true ground-state solutions for a representative set of molecules will be determined using wavefunction stability analysis. This benchmark will allow the development of an effective 'black-box' method for obtaining well-converged training data. Furthermore, the effect of noise on quantum mechanical machine-learning applications will be studied.

The candidate should be interested learning the fundamentals of density functional theory and supervised machine learning. The project will require the development of automated workflows for high-throughput electronic structure calculations and data analysis. Experience with a scripting language (e.g. Python) and UNIX operating systems is advantageous but not mandatory.

Questions about the project can be directed to johannes.margraf@ch.tum.de.