Workgroup Prof. Artur Widera

Open positions

We offer thesis and research projects on all levels

  1. PhD thesis
  2. Master‘s and Diploma thesis
  3. Bachelor‘s thesis and research assistants

If you are interested, please come and see us. For your information, we have compiled some experience from the last thesis projects in our group:


Constructing a source for entangled Photonpairs

Dennis Lönard – Bachelor of Science in Physics

Project:

My bachelor thesis consisted of theoretically describing a setup for the generation of entangled photon pairs and setting it up in the laboratory. The core of this setup consisted of a KTP crystal, whose non-linear optical properties allows the so-called process of spontaneous parametric down-conversion. In this process a low-frequency (blue) laser beam is converted into a higher-frequency (red) laser beam. The crystal is built into a Sagnac interferometer (see figure), so that the blue laser beam is guided through the crystal in both directions. This produces two red laser beams, whos Photonpais, are entangled with each other when they leave the interferometer.

Conclusion:

During my bachelor thesis, I was able to gain a very good insight into everyday laboratory work. Starting with the planning and construction of my experiment up to the documentation and theoretical description of the involved physical processes, I have been able to experience all aspects of an experimental physicists' existence for myself. At the same time I was allowed to make decisions on how to solve problems, but if necessary, I could always rely on the advice of my counselors.


Fermi superfluids in optical disorder potentials

Sian Barbosa – Physics Diploma

Project:

My diploma thesis consists of a more technical and an experimental part. At the beginning, I was involved with several upgrades to the experimental apparatus, a few of which were the planning and rebuilding of the repumper laser system, the optimization of the compressed-MOT sequence as well as the co-creation of a novel method to calibrate the optical speckle disorder potential used in the experiment.

I conducted experiments with molecular Bose-Einstein condensates (mBEC) and unitary Fermi gases consisting of lithium atoms. The gas was displaced inside the trap such that it undergoes so-called dipole oscillations through the disorder potential. I observed the influence of the speckle potential on the oscillation and compared the analyzed data to different theoretical predictions.

Conclusion:

During my diploma thesis, I learned a lot about optics, electronics, programming (especially Python) as well as about the physics of the BEC-BCS crossover and disorder phenomena. Notably, I very much enjoyed the frequent teamwork to overcome technical and, in particular, scientific challenges.


Integration of nitrogen-vacancy centers in polymer waveguides

Jonas Gutsche – Physics Diploma

Project:

On the one hand, my diploma thesis included measurements of the coherence properties of nitrogen-vacancy centers (NV centers) in nanodiamonds. On the other hand, I immersed these nanodiamonds in a photoresist and used direct laser writing subsequently to produce polymer waveguides. As a result, I have integrated a quantum system, which enables magnetometry or thermometry into a microscopic lab-on-chip.

In terms of methodology, my work encompassed a broad spectrum of optical setups in the laboratory, as well as simulations with COMSOL of antennas for microwave excitation of NV centers and the programming and execution of measurement series on their coherence properties. I was also able to gain experience in the cleanroom facilities of the Nano Structuring Center (NSC), where I produced some samples for photoresist structuring and the investigation of nanodiamonds.

Conclusion:

Working on the waveguide project gave me a lot of freedom regarding changes to the microscope setup and trying out different measurement methods. My suggestions were always discussed constructively and implemented in teamwork.

I particularly liked during my work that I was able to tackle "problems" and tasks independently.


Characterization of an optical lattice using Kapitza-Dirac diffraction

Felix Lang – Bachelor of Science in Physics

Project:

During my bachelor thesis, I measured the depth of an optical lattice using Kapitza-Dirac diffraction of a Bose-Einstein condensate (BEC). In this technique, the laser beams forming the optical lattice are pulsed for a short duration, resulting in a matter-wave diffraction in momentum space. The atoms are imaged after a time-of-flight measurement. The depth can be derived by analysing the atoms’ density distribution.

After a first phase of literature research and simulations to identify good measurement parameters I was ready to take data. In the next step I analysed the data and compared it to the theoretical model. Finally, I wrote my thesis.

Experience:

Throughout my bachelor time I could take part in the laboratory routine of the BEC experiment. While doing so, I learnt a lot about atomic physics and quantum gases.

I did the simulations and data analysis using Python which improved my programming knowledge. Furthermore, I was able to learn the basics of scientific writing which will be very helpful for my future.


A tunable laser system for imaging of rubidium at high magnetic fields

 Jennifer Koch – Diploma in Physics

Project:

My diploma thesis comprised the planning and construction as well as the integration of a laser system for the absorption imaging of ultracold rubidium clouds in high external magnetic fields. The planning particularly included the design of the laser system for the given physical applications. Therefore, calculations were carried out which describe the behaviour of the rubidium atoms in an external magnetic field.

Conclusion:

Since my work extends from planning to application, the required skills were very versatile. Therefore, I was able to extend my knowledge in programming, electrical and optical design as well as data analysis.


Interaction of Individual Ultracold Cs Atoms with a Rb Quantum Gas

Steve Haupt – Master of Science in Physics

Project:

My project included -

  • The independent operation of a quantum gas lab with the conception of independent research projects and data acquisition, including the setup and alignment of laser systems
  • Analysis of experimental data and numeric modelling of the system in the programming language python
  • Regular presentation of results in the research group

Schedule:

  • Getting Started/literature research: 10 %
  • Setup of optics and electronics: 10 %
  • Running the experiment and data acquisition in the lab: 35 %
  • Data analysis and programming: 25 %
  • Writing up the thesis: 20 %

Experience:

Working on a quantum gas experiment requires a diligent, precise and methodical working attitude and is rewarded with (partly) worldwide unique measurements and results. I specially liked the combination of idependency and responsibility for small projects (experiment and analysis) and the team orientation on the experiment. Already very soon, one gets the chance to co-decide on important steps for the experiment‘s future.


Preparations for driving Feshbach resonances on ultracold Rubidium and Caesium atoms

Manuel Stein – Diploma Physics

Project:

In my diploma thesis, I have been working towards Feshbach resonances on the Boson experiment. In this context I was dealing with microwave manipulation of atomic states, so I got in touch with high frequency technology – a completely new field for me.

Experience:

Due to the duration of the thesis project I had to practice documenting my work – a very valuable skill. In contrast to the advanced lab classes the work required the close coordination with the other students on the experiment, and even more persistence – however, this allowed to dig very deep

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