The Solid-state Colour Centres team of the Universität Leipzig belongs to the Applied Quantum Systems (AQS) department. The main research topics of the team are the engineering, spectroscopy and applications of colour centres and spin centres in the solid state (mostly diamond and silicon, but also SiC or hBN) for quantum applications.
Based on a long experience within the field of the nitrogen-vacancy (NV) centre in diamond, we are currently focussing our research on emerging defects such as the ST1 (oxygen) and the MgV centre in diamond or the G-centre (carbon) in silicon. This goes along with the search and identification of new defect centres and their properties. Besides, charge-assisted engineering of colour centres is a renowned competence of the team and we are still very active in this field. The method proved to be general and very efficient for NV centres, strongly improving their scalability, charge state stability and coherence time, therefore aiming at their ultimate deterministic creation with high spatial resolution and optimal optical and spin properties. Currently, different approaches are followed to diversify and further improve the method.
The research within the Solid-state Colour Centres team is organised as follows:
- Creation of colour centres (by ion implantation & thermal annealing)
- Imaging & spectroscopy (confocal, ODMR, wide-field, sub-diffraction)
- Defect engineering (charge state, coherence time, doping, Fermi-level tuning, diffusion)
- Applications (qubits, quantum sensors, single-photon sources, quantum registers).
The creation of colour centres in diamond, silicon (and other materials such as SiC or hBN) is a long tradition within the team. The AQS group possesses different ion accelerators providing a large range of ion species, implantation energies and ion fluences, enabling the creation of solid-state defect centres from dense ensembles down to the single centre level and at high-resolution if needed. Beside, lithography and etching capabilities are available on site to conceive devices.
The imaging & spectroscopy relies on modular and versatile optical setups well adapted to the study of specific aspects of the different colour centres. Scanning confocal fluorescence microscopes are the heart of our optical lab. The spectroscopy of new defects (and their charge states) is an important research topic of the team. For example, optically detected magnetic resonance (ODMR) techniques based on NV centres contribute to new developments of material science, at the scale of the single defect and of its very close environment.
The defect engineering is a hot topic of research on colour centres in solid-state as it aims and enables to get the best optical and spin properties of the centres, by improving their formation process and controlling their close environment. This is relevant for the scalability and reliability of qubits with long coherence time, the sensitivity of quantum sensors, the reproducibility and performance of devices.
Applications of colour centres cover a large range of domains, including modern quantum technologies. The team aims at building small quantum registers and quantum nodes, as the building blocks of a future large-scaled quantum computer. The field of quantum sensing was pioneered by NV centres in diamond and is a field of research within the team and AQS group, from basic research to applications. Besides their quantum nature making them good single-photon sources, some of the colour centres offer coherent control of their spin at room temperature.
BSc/MSc/PhD Theses Topics
In case you are interested to join in for a BSc, MSc or PhD, please contact us. We are glad welcoming new people and ideas.
Actual themes for bachelor/master theses:
- Charge states (tuning) of emerging colour centres in diamond. The work consists in studying the different charge states of new colour centres. The goal is to place single centres within a semiconductor junction (p-i-p for example) and to actively.
- Hyperfine couplings in ST1 (oxygen) centre in diamond
- Optical and spin spectroscopy of ST1 centres in diamond
- ST1-NV centres hybrid quantum register at 300 K in diamond
- Red diamond pickups for a quantum guitar
- The role and diffusion of hydrogen in diamond and the passivation of colour centres
- Shallow colour centres produced by plasma treatment of the surface
- NV spin coherence time in doped diamond
- ST1 centre creation yield and properties in p-type and n-type diamond
- Photocurrent spectroscopy for shallow donors in diamond (collaboration with Bergakademie Freiberg)
- Active tuning of G-centres in silicon with p-i-n junction (collaboration with Université de Montpellier, France)
- Vacancies in hexagonal Boron-Nitride: creation, spectroscopy and magnetometry (collaboration with Université de Montpellier, France)
- Rapid thermal annealing (RTA) for new colour centres engineering in diamond (collaboration with ENS Paris Saclay, France)
- Colour centres produced by ion implantation in heated/cooled sample
- Colour centre screening in sapphire
- Surface treatment for charge state tuning of colour centres induced by band bending
- Nanostructures created by self-organised surface masking
- Temperature dependence of the properties of colour centres
