Quantum Acoustics with high-overtone bulk resonators and superconducting qubits: High-Q planar devices, phononlasers, and quantum ghosts

The field of quantum acoustics studies high frequency sounds generated at low temperatures such that quantum mechanical effects become relevant. The studies mainly revolves around propagating quantized sound waves, or phonons, a collective excitation of atoms in solids or liquids. In quantum acoustics, the engineering and design tools described...

A study of two-dimensional superconductivity at oxide interfaces using waveguide resonators

Spectroscopy and imaging of spin waves and valley excitons in two dimensions

Knowledge about the magnetic and electronic properties of materials does not only expand our fundamental understanding of nature, but is also crucial for the development of new technologies. Today’s electronic devices rely on electrical currents to transport and process information, which generate a lot of heat waste via Joule heating. These...

Cavity electromechanics using flipped silicon nitride membranes

Silicon nitride (SiN) membrane electromechanics have shown to serve as excellent systems for applied research on sensing and transduction applications. Nevertheless, their relatively large mass in combination with high-Q also makes them suitable formore fundamental research, where gravitational effects can be tested on large mass quantum states,...

Tunable quantum interfaces between superconducting qubits and microwave photons induced by extreme driving

In this work, I investigate how to implement and quantify \emph{in-situ} tunable quantum interface between superconducting qubits and resonators using external transverse driving fields beyond the rotating wave approximation (RWA). When studying the system under the time-periodic driving field, we typically rely on RWA, a useful technique that...

Coupling Harmonic Oscillators to Superconducting Quantum Interference Cavities

This thesis explores the coupling of microwave cavities containing a Superconducting QUantum Interference Device (SQUID) to a mechanical resonator by means of a flux-mediated optomechanical coupling scheme, and to a Radio-Frequency (RF) circuit via a photon-pressure interaction. While flux-mediated optomechanical systems open the door for the...

Josephson junctions in superconducting coplanar DC bias cavities: Fundamental studies and applications

This thesis investigates fundamental properties of Josephson junctions embedded in microwave circuits, and an application arising from this hybrid approach. We used the versatility of superconducting coplanar DC bias cavities to extract previously inaccessible information on phase coherent and subgap mechanisms of graphene Josephson junctions....

Measuring and controlling radio-frequency quanta with superconducting circuits

In this thesis, we will present the theoretical and experimental work that led to the realization of Radio-Frequency Circuit QuantumElectro-Dynamics (RFcQED). In chapter 1, I will introduce the field of circuit quantum electrodynamics (QED), and the motivations for extending this field to radio frequencies. In chapter 2, we provide a detailed...

Nonlinear couplings for quantum control of superconducting qubits and electrical/mechanical resonators

This thesis explores nonlinear couplings in superconducting circuits with the purpose of achieving quantum control over the elementary excitations of light and motion. It consists mainly of three research themes. The first theme concerns the experimental realisation of a tuneable coupling scheme, giving rise to different interactions with...

Mesoscopic transport in 2D materials and heterostructures

This thesis presents an experimental work on electronic transport in two-dimensional (2D) van der Waals systems. The variety of the physics of the chapters reflects the exploratory character of the Ph.D. study and demonstrates the versatility and the unique properties of some of the members of the vast group of van der Waals materials. In the...

Optomechanics in a 3D microwave cavity

This thesis explores certain technologies that are related to the field of cavity optomechanics; specifically, optomechanics where the cavity is a 3Dmicrowave cavity.

Coherence and nonlinearity in mechanical and josephson superconducting devices

In this thesis, the microwave detection of mechanically compliant objects is investigated. This starts with a system of a suspended metal drum capacitively coupled to a high impedance microstrip resonator. The mechanical non-linear dissipation of the drums is studied. Next, a suspended nanowire coupled to a CPW resonator is studied. With an...

Suspended carbon nanotubes coupled to superconducting circuits

Carbon nanotubes are unique candidates to study quantum mechanical properties of a nanomechanical resonator. However to access this quantum regime, present detectors are not yet sensitive enough. In this thesis we couple a carbon nanotube CNT mechanical resonator to a superconducting circuit which is a root towards such sensitivity.

Carbon nanotubes as electromechanical resonators: Single-electron tunneling, nonlinearity, and high-bandwidth readout

A carbon nanotube (CNT) is a remarkable material and can be thought of as a single-atom thick cylinder of carbon atoms capped of with a semisphere. This is called a single-walled CNT and, depending on how the cylinder is rolled up, CNTs are either semiconducting or metallic. A CNT is made into a mechanical resonator by suspending it between two...