Colour centres in diamond, in particular the nitrogen-vacancy centre, have recently attracted significant attention as versatile tools for quantum information processing, magnetometry and biolabelling, most of these applications relying on the long-lived electronic spin of the nitrogen-vacancy centre. However, for quantum information processing, this centre suffers from mediocre optical properties which limit its use in the absence of photonic structures. In contrast, the silicon-vacancy centre displays remarkable optical properties but so far, its spin degree of freedom had remained elusive.

Using resonance fluorescence, we have shown that the silicon-vacancy centre possesses an optically accessible spin S=1/2. We have then probed the coherence of this spin through coherent population trapping, thus demonstrating the possibility to control the spin with light. Finally, we have achieved coherent control of the spin, thereby showing that the silicon-vacancy centre is a promising spin-photon interface in a quantum network.

Cas nucleases are enzymes that can be programmed with guide RNA to cut DNA with a complementary sequence. This programmability has made Cas nucleases popular genome editing tools, as they can be directed towards any desired genomic sequence by synthetically produced guide RNA. Due to the large number of competing off-targets in a genome, DNA is also cleaved at sequences with only a partial match to the guide. Such off-targeting poses a significant problem for any therapeutic application, and a large number of experiments have been performed to establish a rather peculiar set of empirical targeting rules. These empirical rules are as of yet unexplained, and detail the effect of mismatches at various positions and at various relative distances. We construct a kinetic model that explains the empirical targeting rules, and argue that it can be used to improve on current bioinformatic approaches used to predict off-target locations for genome editing applications.

It is well established that quantum dots (QD) present an atom-like spectrum and constitute a very good indistinguishable and single photon emitter making them promising candidates for quantum information processes. In this talk I will show how their discrete energy structure allows to probe the interactions between a quantum system and its surrounding solid-state environment (fluctuating charges, phonons). By performing two-photon interference experiments in an Hong-Ou-Mandel setup under strictly resonant excitation and as function of the temperature, the QD-phonon interaction can be probed. We have identified two different processes responsible for the loss of the indistiguishability, one because of real phonon transitions, the other one accounts for virtual phonon transitions due to the presence of higher lying excited states in the QD.

Pseudoscalar particles are ubiquitous in models of New Physics and could mediate the interactions of dark matter with the visible sector. Although direct detection experiments are fairly inefficient in constraining such scenarios, they can be tested through a combination of collider, cosmological and astrophysical probes. I will discuss the interplay between these observables in a simple pseudoscalar-mediated dark matter model and comment upon how these constraints evolve within UV-complete New Physics scenarios. Time permitting, I will also briefly discuss alternative ideas about the generation of the dark matter abundance in the Universe which imply a radically different phenomenology at the LHC.

It is demonstrated that topological surface states (TSS) are all around a SnTe bulk sample. It is accomplished by measuring the Shubnikov-de Haas and the de Haas-van Alphen effects for a magnetic field tilted with respect to the [100] crystal direction. The oscillatory magnetization of TSS is calculated taking into account that the bulk SnTe provides a large reservoir of holes. A very good description of experiments is obtained.