Theoretische Arbeiten



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  band structure Urheberrecht: Alex Ziesen

B.Sc.-Arbeit Disorder Effects on Chern Insulators

The topological protection of surface states generates a lot of interest in modern day physics. In this thesis, you will put this to the test by simulating a Chern Insulator under the influence of disorder. Besides the analytical treatment of the clean system, you will set up a Kwant simulation to observe disorder effects on the one-dimensional chiral edge states in various geometries.
Contacts: , Fabian Hassler

  Damped harmonic oscillator Urheberrecht: Lisa Arndt

B.Sc.-Arbeit Quantum harmonic oscillator with dissipation​

Open quantum systems play an important role in many quantum optics applications. In this thesis, you will analyze and simulate a harmonic LC-resonator coupled to a transmission line. The coupling can annihilate excitations in the harmonic oscillator by transferring the energy to the transmission line where it appears as radiation. This effectively leads to dissipation. Among other methods, you will employ the quantum Langevin equation to gain a deeper insight into the dynamics of the system.
Contacts: , Fabian Hassler

  Shapiro setup Urheberrecht: Lisa Arndt

B.Sc.-Arbeit Kramers escape rate with path integrals​

The Kramers problem is to find the rate at which a thermally activated particle escapes from a potential well over a potential barrier. The resulting escape rate has important applications for chemical reactions and phase transitions. In this thesis, you will learn how to use path integrals to calculate the Kramers escape rate of different potential barriers
Contacts: , Fabian Hassler

  Shapiro setup Urheberrecht: Lisa Arndt

B.Sc.-Arbeit Hysteresis in underdamped Josephson junctions​

If the potential of a driven, nonlinear system exhibits more than one (local) minimum, it can show hysteretic behavior. This means that the state of the system depends not only on the current system parameters but also on its history. In this thesis, you will employ a variety of methods to investigate hysteretic effects in an underdamped Josephson junction.
Contacts: , Fabian Hassler

  Detector setup Urheberrecht: Fabian Hassler

M.Sc.-Arbeit Detector theory for microwave photonics with superconducting quantum circuits

In superconducting quantum systems, a significant part of the emitted microwave radiation can be collected and converted to an amplified output signal. This allows for a detailed study of the correlations of the radiation. The statistics of the radiation can offer a valuable insight into the quantum nature of the radiation. It demonstrates phenomena like squeezing or multi-photon processes. In order to study such phenomena theoretically, it is necessary to develop a fitting model for the detector. The goal of this project will be to explore different theoretical detector models for microwave photonics, including the initial detection of the photons, the amplification of the signal, and possible backaction due to the detector.
Contacts: , Fabian Hassler

  Schema zur Illustration des Hall Effekts Urheberrecht: David DiVincenzo

B.Sc.-Arbeit Hall Effect Gyrator

This work will continue recent investigations in our group on the action of an essential component in quantum microwave science, the gyrator. Here you will do calculations of the real-time propagation of electromagnetic fields in this device. Contact: David DiVincenzo

  Qubit-Heterostruktur Urheberrecht: Pascal Cerfontaine

B.Sc.-Arbeit Improved Quantum Dot Qubits

In this project you will explore theoretically variants of the semiconductor quantum dot to perform quantum gate fidelity and readout. There will be an emphasis on tailoring the spin-orbit action to achieve optimal performance, and on varying the electron number and confinement strength. Contact: David DiVincenzo

  Flux Qubit Urheberrecht: Gianluigi Catelani

B.Sc. and M.Sc. Projects Superconducting Qubits

In these projects you will study theoretically some basic properties (energy levels, wave functions, matrix elements) of superconducting qubits such as the fluxonium and the flux qubit. These properties can be accurately calculated numerically in most cases, especially if the problem reduces to that of a quantum particle in a one-dimensional potential. The goal here is to construct an approximate but accurate analytical solution to such a quantum-mechanical problem, using perturbation theory, the WKB approximation, etc. For a B.Sc. project, a symmetric double-well potential will be analyzed. Extension of the results to asymmetric potentials, and to two- or three-dimensional problems, can be considered for a M.Sc. project. Contact: Gianluigi Catelani (