Third-party funded projects

This project employs cryogenic scanning tunneling microscopy (STM) to create atom-based quantum structures on semiconductor surfaces and explore their electronic properties by scanning tunneling spectroscopy. By assembling ionized adatoms with atomic precision, the researchers aim to construct quantum dots and complex arrays with tunable electronic properties. The goal is to gain detailed insights into electron behavior in reduced dimensions, crucial for fundamental science and future quantum technologies.

PDI is currently building up an application laboratory for time-resolved cathodoluminescence spectroscopy, where the detectors will be optimized for ultraviolet wavelengths down to about 180 nm. The system will be capable of measuring classic semiconductor thin-films and heterostructures, 2D materials, as well as 3D nanostructures.

Microcavity exciton-polaritons (polaritons) are light-matter quasi-particles arising from the strong coupling of photons and quantum well excitons in a semiconductor microcavity. Polaritons are composite bosons with µm-sized thermal de-Broglie wavelengths (λdB) of several µm at temperatures of a few Kelvin. A gas of polaritons transitions to a collective single quantum state (an atomic Bose-Einstein-like condensate, BEC) when their λdB exceeds the average inter-particle distance. Own to the long λdB, a polariton BEC can be confined in µm-large intra-cavity traps produced by a lateral modulation of the cavity spacer thickness during the growth process (see figure).

This project aims at the realization of hybrid quantum systems based on the coupling of single electrons and single phonons in the form of acoustic waves in tailored nanostructures. Our focus is the study of the electron-phonon interaction in systems consisting of electrostatic quantum dots placed in a high-quality phonon resonator aiming at reaching the strong coupling regime.

The key objective of this project is the development of integrated terahertz quantum-cascade lasers for high-resolution spectroscopy and future space applications at 3.5 THz and 4.7 THz. These two frequencies are very important for the detection of the OH radical and neutral atomic oxygen, respectively, in atmospheric research as well as in astronomy. The overarching goal is to integrate the QCL chip with optics for optical isolation, outcoupling, and beam shaping as well as an optical fiber.

This project aims to provide new experimental insights into the formation and impact of point defects in Ga2O3. We approach this challenge by cross-linking different experimental characterization techniques, such as micro-Raman spectroscopy and time-of-flight secondary ion mass spectroscopy (SIMS), on molecular beam epitaxy (MBE) grown Ga2O3 thin films deposited in well-defined regimes (i.e. metal- or oxygen-rich). We aim to provide concrete guidelines for the synthesis of Ga2O3 on how to avoid or engineer point defects as a means of controlling its functional properties.

Aharonov-Bohm spectroscopy is a powerful tool to study the quantum statistics of quasi particles in the integer and fractional quantum Hall regimes. Related major activities are in particular driven by the search for non-abelian states which could pave the path towards topological quantum information processing. However, a detailed understanding of how interaction affects the quantum states is still lacking for both quantum Hall effects. We will tackle this challenge by performing phase dependent magneto-transport experiments in conjunction with self consistent model calculations taking into account electron-electron interaction.