Trapped ions are one of the leading platforms for quantum technologies due to their excellent control over their internal electronic and external motional degrees of freedom. Many techniques and interesting effects rely on the coupling of the ions to their motion, which makes precise control of them paramount.

In this work, two novel techniques for motional state detection are presented. They allow the probing of certain motional states with a single measurement, without affecting the motion of the measured ion. These techniques are employed to generate and detect a highly entangled state between two motional modes in a novel manner. Furthermore, we harness the rich and intricate dynamics arising from the coupling of the ion's motion to its electronic degrees of freedom to study the emergence of interference. Theoretical predictions, describing interference both in the quantum and the classical regimes, are verified, offering a new and more intuitive description of interference, not just for trapped ions, but for a variety of systems that can be described in a similar way.

On the other hand, Rydberg excitation with trapped ions enables new interaction mechanisms and makes them extremely sensitive to their surroundings. This thesis presents advances towards Rydberg experiments with longer ion strings and concludes with a first demonstration of coherent population transfer between Rydberg states in trapped ions. The methods developed significantly increase the toolbox for trapped Rydberg ions, enabling more sophisticated experiments, especially when multiple different Rydberg states are involved, and allow more flexibility when using longer ion strings.

Developmental gene regulation depends on the coordinated action of transcription factors, chromatin regulators, and histone modifications that establish and maintain cell-type-specific transcriptional states. In this thesis, I investigate how activating and repressive chromatin factors shape lineage specification in Drosophila melanogaster embryogenesis, with a particular focus on the histone acetyltransferase CREB-binding protein (CBP) and Polycomb-mediated repression. Using genomic, genetic, and single-cell approaches, this work addresses how chromatin states are established during zygotic genome activation (ZGA), how CBP controls distinct steps of transcription, and how active and repressive histone modifications together define developmental trajectories.

The first paper examines the regulation of dorsoventral patterning genes. We demonstrated that RNA polymerase II is recruited to their promoters independently of whether the gene is expressed. Chromatin profiling revealed that H3K27ac closely correlates with gene and enhancer activity, while CBP occupancy at promoters remains invariant. These results identify promoter-proximal pausing as a central regulatory step in early developmental patterning and suggest that inactive CBP can remain associated with silent but poised promoters.

The second paper of the thesis dissects the catalytic and non-catalytic functions of CBP during ZGA. By combining catalytic inactivation and targeted protein degradation, we show that CBP has separable roles in transcriptional elongation and initiation. Its catalytic activity is required for pause release, whereas its non-catalytic activity supports pre-initiation complex stability and RNA polymerase II recruitment. CBP is dispensable for chromatin opening itself and therefore acts downstream of pioneer factors such as Zelda. 

The third paper addresses how CBP activity is regulated across the genome. We show that CBP activity enhances its own recruitment and affects transcription factor binding at regions pioneered by the transcription factor Zelda. Catalytic functions of CBP are shown to be crucial for proper expression of early patterning genes in the Drosophila embryo. Inactive CBP persists at a subset of paused promoters primed by the pioneer factor GAF, and may contribute to Polycomb-associated repression. Together, these results establish CBP as a transcription factor-dependent regulator whose catalytic and non-catalytic functions differently contribute to early development.

The final part of the thesis extends this analysis to later embryogenesis using single-cell nanoCUT&Tag to co-profile H3K27ac and H3K27me3 in individual nuclei. We suggest a new way for epigenetic potential visualization, and found genes where Polycomb repression and gene activity co-occur in one cell lineage. The data distinguishes between two repressive states: active Polycomb-mediated repression and passive chromatin inaccessibility. H3K27me3 associates with genes exposed to activation cues rather than with all silent developmental genes. We further corroborate this conclusion by showing preferential upregulation of lineage-matching genes when H3K27me3 was partially depleted in a mesoderm lineage. 

Together, the studies in this thesis show that developmental epigenetic regulation occurs by the controlled and context-dependent action of co-activators, co-repressors, and pioneer factors that together ensure lineage commitment and maintain robust boundaries between cell identities.

This doctoral thesis examines how participation in a queer mainstream fan culture contributes to meaning-making in the everyday lives of young people. The study is based on ten months of ethnographic fieldwork with fans aged 15–35, the majority of whom were 15–26. The empirical material consists of interviews, participant observations, and fan-created artworks. Through an ethnographic and queer theoretical approach, the dissertation foregrounds the participants’ own perspectives, with particular attention of time, emotion and everyday life. Across four empirical chapters, the dissertation analyzes different temporal and  affective dimensions of fandom.

The first chapter ”enchantment,” examines how fans orient themselves towards enchanting cultural experiences.  If queerness in everyday life has been associated with vulnerability and pain, engaging with queer fan cultures offers a new optic through which queerness appears in a different light. Within the enchanted framework, queerness is not only linked to suffering but also to beauty and possibility. The chapter further highlights how a foundational aspect of being a fan, lays in meeting like-minded others and creating a community. The orientation towards enchantment becomes meaningful when experienced collectively with other fans.

The second chapter, ”Ecstasy,” examines how enchantment is intensified through collective ecstatic states. Drawing on empirical material describing fans waiting for a pop concert to begin, the chapter illustrates how playful and seemingly ­ ”silly” forms of joy, generates a shared emotional intensity. Interpreted through queer temporal perspectives, these moments are conceptualized as forms of micro-ecstasy. 

The third chapter, ”Escapism,” shifts attention from the intensity of ecstasy to quieter practices characterized by withdrawal, waiting and seclusion. The chapter sheds light on the ”insivible” fans that are less drawn to the social dimensions of fan cultures. They engage with fandom in more private ways. These fans create meningful experiences of enjoyment and emotional attachment in solitude. The findings suggest that escapism becomes significant by providing secluded spaces for comfort, rest and pleasure.  

The fourth chapter ”The hangover,” explores the processes through which enchantment transforms to disenchantment. Here, toxic community dynamics, algorithmic platform logics and emotional exhaustion lead fans to renegotiate their sense of belonging within fan communities. This chapter therefor examines the ambivalent and at times painful dimensions of fan culture. Experiences of disenchantment also raise questions concerning future participation and how fans manage their ”personal archives” of fan engagement. Decisions to leave a fan community often involve practices of archiving, erasing or preserving traces of participation. These negeotations are analyzed through queer theocratical perspectives on everyday archiving. 

The final chapter ties together the thesis’ main arguments and reflects further upon how ideas of queer temporality can contribute to the field of youth culture studies.