Strong coupling of a single ion to an optical fibre cavity

Achieving strong coupling between a single ion and a cavity is an important condition for cavity quantum electrodynamics, mainly for its applications in quantum networks, quantum computing and quantum interfaces. While strong coupling has been achieved in various physical systems, so far it remained elusive for single atomic ions. In this thesis I present the first observation of strong coupling between a single ion and an optical cavity. Our system is a hybrid system where a fibre based Fabry-Pérot cavity was incorporated to a 3D Paul trap. The position of the ion, relative to the cavity mode, was adjusted by applying additional rf signals on the radial electrodes of the trap, in order to maximise the coupling between the ion and the cavity. The coupling strength was measured to be g = 2π × (12.3±0.1) MHz, which exceeds both the atomic decay rate, γ = 2π × 11.5 MHz, and the cavity decay rate, κ = 2π × (4.1 ± 0.1) MHz, placing the ion-cavity coupling in the strong coupling regime. Cavity assisted Raman spectroscopy was used to precisely characterize the ion-cavity coupling strength, and observe a spectrum featuring the normal mode splitting in the cavity transmission due to the ion-cavity interaction. Due to geometric constraints in our trap, Doppler cooling was not optimal along the cavity axis, hindering the localisation of the ion and thus its coupling to the cavity. To improve the localisation of the ion, cavity cooling was used to efficiently cool the ion along the cavity axis. By using cavity cooling, we obtain an enhanced ion-cavity coupling of g0 = 2π × (16.7±0.1) MHz, compared with g0 = 2π × (15.2±0.1) MHz when using only Doppler cooling

Research data for research paper: Precise positioning of an ion in an integrated Paul trap-cavity system using radio frequency signals

<div>The data provided is the data used in 11 of the figures in the research paper. Each sheet in the spreadsheet is labelled by the figure label they correspond to in the research paper.</div><div><br></div><div><b>Abstract from research paper:</b></div><div>We report a novel miniature Paul ion trap design with an integrated optical fibre cavity which can serve as a building block for a fibre-linked quantum network.</div><div>In such cavity quantum electrodynamic set-ups, the optimal coupling of the ions to the cavity mode is of vital importance and this is achieved by moving the ion relative to the cavity mode. The trap presented herein features an endcap-style design complemented with extra electrodes on which additional radiofrequency voltages are applied to fully control the pseudopotential minimum in three dimensions. This method lifts the need to use three-dimensional translation stages for moving the fibre cavity with respect to the ion and achieves high integrability, mechanical rigidity and scalability. </div><div>Not based on modifying the capacitive load of the trap, this method leads to precise control of the pseudopotential minimum allowing the ion to be moved with precisions limited only by the ion's position spread. We demonstrate this by coupling the ion to the fibre cavity and probing the cavity mode profile. </div

A Rare and Dangerous Combination of COVID-19, Lemierre Syndrome, and Carotid Pseudoaneurysm: A Case Report

Lemierre syndrome is a rare complication of oropharyngeal infection that causes septic thrombophlebitis in the internal jugular vein. Since the onset of the COVID-19 pandemic, this condition has been dangerously overlooked and poses an even greater threat when complicated by vascular pathologies. A case is presented where the patient required emergency endovascular exclusion of a right internal carotid artery pseudoaneurysm due to Lemierre syndrome. The treatment included stent graft placement and drainage of a neck abscess, along with appropriate antibiotic treatment during hospitalization. Recognizing this diagnosis requires a high index of suspicion, particularly during the COVID-19 pandemic. The complexity of the disease necessitates extensive multidisciplinary collaboration for effective treatment

Data set for publication 'Enhanced ion–cavity coupling through cavity cooling in the strong coupling regime'

Data set for the figures in the publication 'Enhanced ion–cavity coupling through cavity cooling in the strong coupling regime.Scientific Reports 10, 15693 (2020)'The data are the ones to produce the figures in the publication. Details can be found within the spreadsheet.Abstract:Incorporating optical cavities in ion traps is becoming increasingly important in the development of photonic quantum networks. However, the presence of the cavity can hamper efficient laser cooling of ions because of geometric constraints that the cavity imposes and an unfavourable Purcell effect that can modify the cooling dynamics substantially. On the other hand the coupling of the ion to the cavity can also be exploited to provide a mechanism to efficiently cool the ion. In this paper we demonstrate experimentally how cavity cooling can be implemented to improve the localisation of the ion and thus its coupling to the cavity. By using cavity cooling we obtain an enhanced ion–cavity coupling of 2π×(16.7±0.1) MHz, compared with 2π×(15.2±0.1) MHz when using only Doppler cooling.</div