Thomas Luschmann

Offered Bachelor’s or Master’s Theses Topics

Quantum acoustics in novel piezoelectric multi-layer systems

The field of quantum acoustics aims to investigate quantum mechanical effects in acoustic resonator structures. Combined with e.g. optical and / or superconducting circuits, this offers the possibility to create quantum hybrid systems, which are discussed in the context of storing and converting quantum states. In this project, we shall investigate one of the building blocks, i.e. the surface acoustic wave (SAW) resonator. With your help, we aim to develop and optimize SAW resonators operating in the GHz frequency range with high quality factors and test these devices at moderately low (3-10K) and millikelvin temperatures. Your bachelor thesis will bring you in touch with state-of-the-art nanofabrication technology and introduce you to microwave spectroscopy tools like vector network analyzers, as well as cryogenic measurement environments. Careful data analysis of the transmission and reflection data of these resonators combined with modeling will put you in the position, to make a meaningful contribution to the creation of quantum hybrid systems.

suitable as

• Bachelor’s Thesis Physics

Supervisor: Hans-Gregor Hübl

Quantum acoustics in the giant atom limit

The field of quantum acoustics aims to investigate the interaction between matter and sound, in a similar way that quantum optics (QO) studies the interaction between matter and light. In detail, we enable this interaction using surface acoustic waves (SAWs) and artificial atoms (Qubits) formed by superconducting quantum circuits. Quantum acoustics offer interesting differences to quantum optics. The propagation speed of sound in solids is approximately five orders of magnitude slower than for light in vacuum, leading to the SAWs much shorter wavelengths compared to electromagnetic waves. This allows the exploration of the “giant atom” regime in which the size of the artificial atoms becomes comparable to or larger than the wavelength of the interacting wave. In this regime, interesting physics like interference and non-exponential decay of quantum states become accessible. We are looking for a motivated master student for a master thesis in the context of quantum acoustics. The goal of your project is to investigate the static and dynamic interplay between surface acoustic waves and one (or more) superconducting qubits. Your thesis project includes the fabrication of aluminium-based superconducting circuits on silicon and lithium niobate using state-of-the-art nano-lithography and metal deposition techniques. Subsequently, these circuits shall be experimentally investigated in a cryogenic microwave measurement setup. As such, the project will allow you to gather expertise in quantum physics, nanofabrication, microwave engineering, and cryogenic techniques.

suitable as

• Master’s Thesis Condensed Matter Physics
• Master’s Thesis Applied and Engineering Physics
• Master’s Thesis Quantum Science & Technology

Supervisor: Hans-Gregor Hübl

Ultra-sensitive microwave spectroscopy setup for electron spin resonance

Planar superconducting microwave resonators are key for the ultra-sensitive detection of spin properties. We employ planar microwave resonators fabricated from various superconducting materials like Nb, NbN and NbTiN and test their performance with respect to field and temperature stability. With your help, we aim to improve our resonator design and test their performance with an existing variable temperature setup operating between 1.5 and 300K. You shall further asses the overall performance of the setup using electron spin resonance. Your bachelor thesis will bring you in touch with state-of-the-art microwave spectroscopy tools like vector network analyzers, as well as cryogenic measurement environments. In addition, you will fabricate and optimize microwave resonators and perform the microwave spectroscopy measurements. Moreover, the careful data analysis of the magnetic field dependent datasets will put you in the position, to make a meaningful impact on novel spin resonance spectroscopy approaches.

suitable as

• Bachelor’s Thesis Physics

Supervisor: Hans-Gregor Hübl