QPIT for students

A number of courses at DTU Physics are taught by QPIT staff members.

We also welcome any dedicated student to join our highly motivated team to work on one of our research topics. We offer a large range of bachelor and master projects within the fields of quantum optics, solid state optics, spintronics, quantum sensing and quantum information

Possible supervisors:

A few examples of completed Master projects:

Squeezed light from a Silicon Nitride micro-ring resonator

In his theoretical Master's thesis work, Matthieu Manceau investigates the possibility of using well-known techniques from quantum optics in integrated photonics. More specifically, he looks at the feasibility of generating squeezed coherent states in integrated optical resonators built using Silicon Nitride waveguides. Silicon Nitride has a third-order non-linearity making it possible to produce squeezed coherent states by four-wave mixing and Kerr squeezing.


Super-Resolution with Coherent States

Interference of light fields plays an important role in various high-precision measurement schemes. It has been shown that super resolving phase measurements beyond the Rayleigh diffraction limit can be obtained either by using maximally entangled multi-particle states of light or using complex low efficiency detection approaches. In addition to their high technical complexity, these methods lack robustness or efficiency rendering the sensitivity performance above the shot noise limit. In this thesis, we show that super resolving phase measurements at the shot noise limit can be achieved without resorting to non-classical optical states or to low-efficiency detection processes. Using robust coherent states of light, high-efficiency homodyne detection and a deterministic binarization processing technique, we beat the diffraction limit by 12 times at the quantum shot noise limit. 

An On-chip efficient single photon source

The ability to produce single photons on demand in a single spatial mode facilitates the implementation of quantum computing and quantum communication protocols. 
In this project, work on the controlled coupling of an NV center to two different types of dielectric waveguides is performed. First we demonstrate the coupling to a tapered standard optical fiber (TF) with a cone-like structure and second we investigate the potentials of coupling to the mode of a SiN gap structure (SNGS). 
Finite Element Method (FEM) simulations of the supported modes have been made for both structures. Optimized parameters for the structure have been found in relation to a maximization of the NV spontaneous emission decay rate into the corresponding single mode waveguide structure. The results of these simulations are presented in Fig. 1 and 2. 
Experimental investigations both in relation to fabrication and coupling have been performed. Fluorescence images from TF and SNGS are depicted in Fig. 3 and Fig. 4, respectively. In terms of coupling experiments, the tapered optical fiber was found to be the more promising one of the two different dielectric structures due to the detrimental background fluorescence of the SiN waveguide. As a next step we plan to enhance the coupling strength by developing a hybrid metal-dielectric structure.