Description
The Poster Session is held on Tue and Thu. All posters are to be presented on both days. However, due to technical reasons, the contributions are only listed in the timetable of Tue.
Magic-angle twisted bilayer graphene has received a lot of attention due to its flat bands that lead to intricate correlated phases. However, control over the system parameters of such devices is limited. We propose a single graphene sheet with adatoms periodically placed on top as an alternative system that realizes flat bands. Performing first principle calculations, we obtain realistic...
2D-materials represent some of the simplest systems for the study of a variety of different phenomena, including superconductivity magnetism and other phase transitions. A prototypical 2D-system can be constructed depositing a noble gas over a substrate with a weak interaction between the two, such as graphite, to create a tunable layered crystalline structure. In this work we demonstrate how...
We analyse the dynamics and universality of Dirac and nodal loop gap closures under a continuous quench by employing the Landau-Zener formalism. We reveal that the scaling behaviour of the topological defect density can deviate from the prediction of the Kibble-Zurek mechanism when the gap closure is extended. This is also observed in the presence of multicriticality, where we recover...
Superconductor-semiconductor hybrids are platforms for realizing effective p-wave superconductivity. Spin-orbit coupling, combined with the proximity effect, causes the two-dimensional semiconductor to inherit p ± i p intraband pairing. An external magnetic field can then result in transitions to the normal state, partial Bogoliubov Fermi surfaces, or topological phases with Majorana modes....
Poly(furfuryl alcohol) (PFA), produced through polymerization of furfuryl alcohol, is a thermosetting polymer and basis of thermoset resin systems, and it has been investigated in several studies (IR, 13C-NMR, Raman, DSC), new aspects being considered each time. The target of the present study, performed within the Interreg Italy Austria project ITAT1023 InCIMa and ITAT1059 InCIMa4, is the...
Magnetite (Fe3O4) is the first magnetic material ever discovered. At 125K, the system undergoes a metal-insulator transition (MIT) accompanied by a structural transition as well as a magnetic rearrangement, the so-called Verwey transition.
Light offers the appealing possibility of manipulating the electronic and structural properties of matter. Here, using two different photon-energies, we...
Dielectric-Loaded Surface-Plasmon-Polariton waveguides (DLSPPWs) offer suitable solutions to guide mid-IR light along the surface of semiconductor-based optoelectronic devices. Since the main portion of the mode in typical semiconductor-Au-Ge plasmonic layer structures is propagating outside in the surrounding medium, this geometry allows to efficiently address chemical sensing of liquids...
Terahertz quantum cascade patch antenna lasers are a promising technology to realize surface emission in the terahertz range. The laser emission frequency can be tuned by changing the patch size and array geometry. Biasing these sub-wavelength structures requires metallic connection lines with limited effect on the patch mode.
We present epilayer-down mounted patch arrays on a substrate...
In this work we present the realization of low-density polyethylene (LDPE) ridge-waveguides using spinning-deposition, standard-lithography and oxygen-plasma-etching for patterning. Parameters such as toluene-solvent concentration, spinning-speed and bake-out-process temperature in a vacuum-oven are optimized in order to obtain the required film-thickness. Ellipsometry data shows a...
Infrared spectroscopy is a reliable tool for chemical sensing in various fields from industry over environmental monitoring to medicine. Interband cascade lasers (ICLs) have proven to be important light sources for such applications. Utilization of ring-shaped laser geometries provides a collimated beam profile as well as vertical light emission. We combine the ring geometry with the ICL...
Quantum cascade lasers facilitate compact optical frequency comb sources that operate in the mid-infrared. Enhancing the optical bandwidth of these chip-sized lasers is important to address their application in broadband high-precision spectroscopy. We provide an investigation of the comb spectral width and show how it can be optimized to obtain its maximum value. The interplay of nonoptimal...
The quantum cascade laser has evolved to be a compact, powerful source of coherent mid-infrared light. However, its fast gain dynamics strongly restricts the formation of ultrashort pulses. As such, the shortest pulses reported so far were limited to a few picoseconds with some hundreds of milliwatts of peak power, strongly narrowing their applicability for time-resolved and nonlinear...
A convenient light source together with a suitable detector comprise the basic setup for sensing and imaging applications.
We present a flexible terahertz (THz) frequency comb source operating at room temperature that provides great freedom in the spectral content design. A robust setup merges two mature technologies, namely optical fibre communications and opto-electronic frequency...
The photon-driven nature of the transport in terahertz quantum cascade laser can be exploited to detect light. Responsivities higher than 16 V/W are demonstrated on a patch-array antenna coupled device. The ~ps lifetimes also allows ultrafast operation. Preliminary studies suggest bandwidth higher than 5 GHz.
We present ring-shaped THz Quantum Cascade lasers operating in four different emission regimes, including single-mode, harmonic state, dense comb, and chaotic multimode emission. The dense comb regime exhibits over 30 equidistant modes covering a bandwidth of 622 GHz. A single and narrow beat note at the roundtrip frequency is indicating comb formation. Our experimental results are explained...
The recent discovery of AV$_3$Sb$_5$ (A=K,Rb,Cs) has uncovered an intriguing arena for exotic Fermi surface instabilities in a kagome metal, displaying charge ordered and superconducting phases with unconventional properties. In this presentation I will discuss the understanding of these instabilities that emerges from a range of – partially complementary and partially controversial –...
The Kitaev model on the honeycomb lattice is a paradigmatic system known to host a wealth of nontrivial topological phases and Majorana edge modes. In the static case, the Majorana edge modes are nondispersive. When the system is periodically driven in time, such edge modes can disperse and become chiral. We obtain the full phase diagram of the driven model as a function of the coupling and...
The relation between the pseudogap phase and the superconducting dome in high Tc superconductors is still not well understood despite intense research. To develop better insight into this relation and understand the electronic properties of these materials, we study the Fermi surface via time- and angle-resolved photoemission spectroscopy (tr-ARPES). We measure the size and topology of the...
Electron transfer is a crucial part of chemical reactions which drive everyday processes. With the help of an electro-chemical radiofrequency scanning tunneling microscopy setup, we are observing single electron mediated oxidation-reduction processes in transition metal corroles. We are specifically distinguishing different valence states of a transition metal ion and controllably switch from...
The maximal vortex velocities $v^*$ are limited by the flux-flow instability (FFI) and contain information on the scattering mechanisms of charge carriers in the samples. However, the nucleation of FFI does not necessarily occur in the entire sample but can have a local character. Here, we demonstrate that the $v^*$ in superconducting MoSi films with smooth edges can exceed $v^*$ in films with...
Extension of nanostructures into the third dimension is now a major approach in magnetism, superconductivity, and spintronics due to recent advancements in synthesis techniques and discovery of rich novel phenomenology induced by geometry, curvature, and topology effects. Herein, certain shape and curvature induced effects in ferromagnetic 3D nanostructures are presented, with focus on Co-Fe...
High-performance and sustainable technologies call for novel light-weight high-temperature structural materials as gamma-TiAl-based alloys, which – in terms of weight – clearly outperform classical Ni based alloys. The typical research focus lies on their mechanical properties. However, in order to correctly interpret electrical materials testing techniques also their electrical behavior is...
Changes in the ordering and electric metastable effects make the precise power rating of photovoltaic copper-zinc-tin-sulphide (CZTS) devices difficult. Reliable measurement routines are crucial for total yield prediction and investment return calculations. The aim was to find faster methods to stabilize CZTS solar devices using illumination and thermal treatment. The method used here on CZTS...
The goal of our work is generating an automated workflow for calculating quasi-particle band gaps within the so-called GW method. The resulting protocol is applied to a large materials dataset of about 100 materials, from binary to quaternary compounds. Conventional approaches of performing these calculations require significant amounts of computational resources and user interaction,...
Es werden die ersten Highlights des FFG Projekts der FTI-Initiative “Produktion der Zukunft” präsentiert. Das Ziel ist, eine konventionelle, erdölbasierte Wickelfolie für Supermarkt-Palettenverpackungen durch eine biobasierte, recycelbare Stretchfolie zu ersetzen. Da biobasierte Kunststoffe meist teurer, steifer und weniger dehnbar sind, sollen funktionale Perforationsmuster entwickelt werden,...
The need for 3D integration in semiconductor industry has driven the key technology of wafer bonding to a new level. Low temperature plasma activated wafer bonding (LT-PAWB) requires high adhesive forces between two polished surfaces at reduced annealing temperatures. In this process silicon wafers with a deposited dielectric layer (SiO2, SiCxNy) are activated, contacted and annealed. The...
The controlled motion of single molecules gives deeper understanding of the relation between molecular motion and the chemical and geometrical properties of molecules on the surface. However, the thermal motion of molecules is a stochastic process, which is difficult to control. Here, we have used scanning tunneling microscopy, kept at temperatures of about 7 K and ultrahigh vacuum conditions,...
Hybrid material systems combining semiconductors and magnetic nanostructures are prospective building-blocks for the next generation of high-density recording media. In phase-separated (Ga$\delta$FeN) layers grown epitaxially on Al$_{x}$Ga$_{1-x}$N buffers, the specific concentration of Al determines the density of strain-related dislocations, which allow controlling the preferential...
The desire to combine properties such as ready availability, low price and biodegradability makes cellulose and its derivatives an ideal prerequisite for different applications. We demonstrate a new approach of patterning thin films based on Trimethylsilyl-cellulose (TMSC) via proximity X-ray lithography, creating positive and negative tone structures in one single exposure at the same energy...
Solid-oxide fuel cell (SOFC) cathode materials like lanthanum–strontium manganite (La$_{0.8}$Sr$_{0.2}$MnO$_{3}$, LSMO) are an active field of study for efficient chemical energy conversion into clean electricity. Since the surfaces play a crucial role in the relevant reactions, closer investigation is needed for establishing a model. We use our setup for pulsed laser deposition (PLD) and...
Little is known about the surface tension of pure liquids in contact with their pure gaseous phases, i.e. without the presence of other gases or contaminants. This is surprising given that contaminants are known to greatly affect surface tensions values.
Recently we have developed a method to dose liquid water with UHV purity using a small cryostat[1]. We combine this approach with the...
Collecting quantitative low-energy electron diffraction [LEED I(V)] data normally requires expensive acquisition systems that complement LEED control electronics. We design a fully functional setup, based on an Arduino controller, combining easily and cheaply available parts as part of the “Vienna Package for TensErLEED” (ViPErLEED). In addition to standard LEED I(V) signals, the design is...
Redox chemistry on perovskite surfaces attracts attention due to these materials’ promising catalytic properties and the presence of ferroelectricity in many perovskites. In this study, STM and XPS have been used for investigating the interaction of cobalt with the $KTaO_3(001)$ surface. In UHV conditions, the freshly cleaved $KTaO_3$ surface was exposed to water vapor prior to cobalt...
A new In Situ Spectroscopy beamline (X07DB) has been recently established at the Swiss Light Source (SLS). The beamline is now open to the user community via proposal access, offering studies of solid-gas and solid-liquid interfaces using ambient-pressure X-ray photoelectron spectroscopy. Two experimental endstations are available, capable of studying "real" catalysts such as...
Perovskite surfaces are often probed by diffraction techniques, and a commonly measured (1x1) pattern is interpreted as a (1x1) atomic arrangement. We use the KTaO3(001) to demonstrate the pitfalls of this assumption. Cleaving KTaO3(001) in vacuum and a subsequent exposure to water vapour results in the formation of a (2x1) reconstruction. The (2x1) pattern is only observed in LEED at very low...
We demonstrate an approach to manufacture 2D materials into nanoribbon networks. Small organic molecules deposited on 2D materials can form nanoneedles aligning predominantly in either zig-zag or armchair orientation. This study shows their usage as masks. These hybrid heterostructures are plasma etched resulting in single-crystal nanoribbon networks. Raman spectroscopy, atomic force...
The accelerator science has long sought to increase the quality factor of SRF cavities. The approach is to use Nb$_3$Sn in a thin film form grown on Cu. One main advantage of Nb$_3$Sn is its high critical temperature- twice the currently used Nb. The challenge of growing Nb$_3$Sn directly on Cu is multiple and requires the use of a barrier layer in between Nb$_3$Sn and Cu. This work hence...
Epitaxial Ge0.9Sn0.1 layers are well-suited for Si-integrated optoelectronics. However, their thermal stability at the nanoscale is far from a complete understanding. For detailed insights into the decomposition process induced by the components' negligible miscibility and the low Sn melting temperature, in situ TEM experiments have been performed. To trace the sample evolution upon annealing,...
A nuclear excitation following the capture of an electron in an empty orbital has been recently observed for the first time. The experiment remains particularly fascinating and unexplainable by state-of-the-art theory. So far, the evaluation of the cross section of the process has been carried out widely using the assumption that the ion is in its electronic ground state prior to the capture....
The n2EDM experiment will search for the neutron electric dipole moment, to elucidate the Baryon Asymmetry of the universe.
The precession frequency of spin-polarised neutrons will be measured in a magnetic field and an electric field, in a Ramsey-type experiment.
The magnetic field will be continuously probed by a laser via the spin precession of Hg atoms in the precession chamber to...
A powerful and adaptable tool for performing experiments with positrons and positronium, is a positron trap. Positrons can be confined by using magnetic and electric fields combined with Nitrogen and CH$_4$ buffer-gas. Such a device can produce ~10$^5$ e$^+$/s in bunches with a diameter of 1-2 mm and an energy spread of approximately 50 meV.
Such a trap is under construction at SMI and will...
How can I improve the learning success in my physics exercise class? Can I prepare an engaging lesson efficiently? Our Engaging Physics Tutoring (EPT) project addresses these questions by providing a hands-on didactical tool-box for physics teaching assistants. 13 fully worked out lessons for introductory physics as well as nuclear and particle physics lectures are available online as eBooks....
A Wien (velocity) filter for the Ion Laser InterAction Mass Spectrometry (ILIAMS) facility at the Vienna Environmental Research Accelerator (VERA) was characterized and commissioned.
First, simulations via the ion beam simulation program SIMION were done to find the best position in terms of mass separation for a Wien filter within the facility.
After installation of the Wien filter,...
We present results from a pilot study at high spectral resolution (R=100,000) of diffuse interstellar bands (DIBs) in the near-infrared J-band with VLT/CRIRES. Several so far unknown near-IR DIBs are detected. The membership to DIB families is investigated, as indication of the origin from common carriers. The DIB sightlines are characterized to unprecedented accuracy and precision due to the...
Excellent particle detection momentum threshold, together with cost-effective scale-up prospects, make the proposed TPC, a strong candidate for reducing the systematic errors in future neutrino oscillation experiments. Thousands of photons per primary electrons are produced through a gas electron multiplier. These photons, normally in the UV range, are shifted to visible using a PEN wavelength...
This contribution describes how the so-called Barbero–Immirzi parameter, which is akin to the theta parameter in QCD, deforms the SL(2,R) symmetries of the gravitational boundary data on a null surface. Our starting point is the definition of the gravitational action and its boundary terms. We introduce the covariant phase space and explain how the Holst term alters the symmetries on a null...
Dihydrogen halide clusters are the subject of various theoretical and experimental studies. In their anionic state they are weakly bound complexes and can provide insight into dynamical processes in chemical reactions. Here we report the three-body reaction rate of Cl$^-$ with H$_2$ forming the Cl$^-$(H$_2$) complex, as well as the temperature dependence of this reaction in the range of 10 –...
Experimental observation of state-to-state interactions, here specifically reactive encounters of ions and molecules, requires both precise control of the initial conditions and sufficient resolution of the product states. We have designed and simulated a new crossed beam velocity map imaging spectrometer, which exploits coincidence detection of products to push the experimental possibilities...
Different neutral and charged interstellar molecules constitute the building blocks for a rich reaction network in the interstellar medium (ISM). The abundance of negative ions in the ISM and their role in the chemistry of these environments has been subject to long-standing discussions in astrochemistry. Photodetachment cross-section studies are crucial for predicting the abundance of anions...
A single ring of sub-wavelength spaced dipole-coupled quantum emitters possesses only few radiant but many extraordinarily subradiant collective modes. These exhibit a 3D-confined spatial radiation field pattern forming a nano-scale high-Q optical resonator. Proven to show promising results in the single-ring case, a spin-wave Ansatz was chosen to investigate the radiation properties of...
In this work, we studied dissipative phase transitions (DPT) in optomechanical systems. We applied the stability analysis at a well-defined thermodynamic limit to arrive at the corresponding phase diagram, which exhibits two types of instability lines: soft and hard mode instabilities—directly related to DPTs. The optomechanical phase diagram shows a rich structure composed of first and...
Simulating quantum magnetism is one of the major high goals pursued currently in the field of ultracold atoms and molecules. Recently a new approach was suggested for the production of a dipolar quantum gas utilizing both electric and magnetic dipole moments. The scheme relies on exciting dysprosium atoms into a superposition of long-lived opposite-parity states near degeneracy. We have set up...
The combination of quantum gas microscopy and ultracold polar molecules promises experimental access to rich new many-body physics. Our experiment focuses on achieving this using the KCs molecule. We present recent work on optical transport of ultracold atoms using a focus tuneable Moiré lens. The use of this lens makes the setup more robust, compact and stable compared to conventional...
Trapped atoms and atomic ions are among the best-controlled quantum systems which find widespread applications in quantum science. However, a similar exquisite control over molecules has remained elusive so far due to their complex energy-level structure with additional rotational and vibrational degrees of freedom. We employ a quantum-logic protocol which uses a single co-trapped atomic ion...
Molecular quantum optics deals with phenomena related to the wave nature of molecules, in particular the interaction of molecules with light. Modern molecule interferometry observes quantum effects in massive particles and more recently also biologically relevant molecules. The high sensitivity to beam shifts and wave dephasing can be used to extract a variety of molecular electronic...
Accurately controlling the dynamics of physical systems by measurement and feedback is a pillar of modern engineering; Achieving this in an optimal way is a challenging task that relies on both quantum-limited measurements and specifically tailored algorithms for state estimation and feedback. We demonstrate real-time optimal control of the quantum trajectory of an optically trapped...
We provide an argument to infer stationary entanglement
between light and mechanical oscillator based on measurement of light only. We propose an experimentally realizable scheme involving an
optomechanical cavity driven by a resonant, continuous-wave field operating in the non-sideband-resolved regime. This corresponds to the conventional configuration of an optomechanical position- or...
We have studied how a coherent phenomenon can control the polarization rotation in the Rb vapour. Experimentally we have observed a sharp rotation spectrum in the vicinity of electromagnetically induced transparency in a V-type system. The dependencies of various system parameters have been investigated. Theoretical models have been developed to explain the observed phenomena. The observed...
The ASACUSA CUSP collaboration at the Antiproton Decelerator (AD) of CERN aims at a precise measurement of the ground-state hyperfine splitting of antihydrogen, which promises to be one of the most sensitive tests of CPT symmetry. A dedicated mixing trap serves as a source for in-flight spectroscopy. While antiprotons are supplied from the AD, positrons from a $^{22}$Na source are slowed down...
We have built an enhancement cavity able to sustain 20 watts of intracavity power in the deep-UV range (244 nanometer) on several hour time scales, in a vacuum chamber designed for muonium 1S-2S precision spectroscopy. These performance are reached when fluoride coated mirrors are in a low oxygen pressure environment ($10^{-3}$ millibar), meanwhile in higher vacuum ($10^{-8}$ millibar) up to...
In commercial telecommunication and high-precision spectroscopy, single-sideband modulators are widely used for optical frequency shifting. Drifts of the bias voltages, which control the phases between the arms of the dual-parallel Mach-Zehnder modulator, require stabilization to enhance suppression of the carrier and the second sideband. Modern methods rely on the modulation of these bias...
Traditional laser locking methods rely on reference sideband generation from the main carrier. A modulation-free alternative is the use of spatial modes in an optical cavity. In this poster, we present an all-passive modulation-free method of locking a laser to an optical resonator. We engineer the input beam to contain 2nd order spatial modes of a non-confocal 3-mirror cavity. This method is...
The terahertz (THz) region lies in between of the RF and optical spectral regions and is expected to become a part of novel wireless links due to its high bandwidth and safety. Therefore, a refined control over THz radiation is required.
We investigate the influence of spatially controlled, near-infrared induced charge carriers in high-resistivity silicon on a collimated THz beam. Our...
Bringing milligram-scale mechanical oscillators to the quantum regime for enhanced sensing is currently a very sought after goal. Prospects range from investigation of macroscopic quantum mechanics and exploration of quantum aspects of the gravitational interaction to searches of unknown (fifth) forces. Sufficient isolation and achieving quantum control have remained challenging in this mass...
The competition between short-range and cavity-mediated infinite-range interactions in a cavity-boson system leads to the existence of a superfluid and a Mott-insulator phase within the self-organized regime. We quantitatively compare the steady-state phase boundaries of this transition measured in experiments and simulated using the Multiconfigurational Time-Dependent Hartree Method for...
We study fundamental effects of spontaneous emission with a mirror, which is used to couple a Ba$^+$ ion with its retroreflected fluorescence light. This back-reflected fluorescence induces a mechanical effect on the ion's motion, varying sinusoidal with the ion-mirror distance resulting in a force.
We present a method to control this force to study the effect of back-reflected light on the...
We propose a new platform to investigate the interaction of antiprotons with ordinary matter at the kinetic energy of a few K or lower. We will confine antiprotons and negative ions in a Penning trap to prepare both species at low temperature within the same trapping volume. After co-trapping, the anions will be photodetached with a laser pulse to form cold neutral atoms, which will interact...
Applications of lasers in quantum metrology require precise control of the laser frequency. This is usually achieved by locking the frequency of a slave laser at a tunable offset from a master laser. Here we present a new scheme for a robust and high precision laser offset frequency locking. A hybrid frequency discriminator generates an error signal that has a wide capture range of more than...
Preparing a massive oscillator near the quantum limit has become a central goal in fundamental sciences.Optomechanics, where a mechanical mode is coupled to a light field, allows to operate a mechanical object near its quantum ground state. Our setup consists out of a microwave SQUID based cavity inductively coupled to a mechanical cantilever.Despite being deeply in the unresolved sideband...
We reported depletion spectra of Rb2+ complexed with up to ten Helium atoms. The ions were formed by doping helium nanodroplets in a pickup cell filled with low-density Rb vapor and subsequent electron ionization. Two absorption bands were observed between 920 and 250 nm, due to transitions into the 12Σu+ and 12Πu states. The transitions are blue- and redshifted, respectively, when the number...
Quantum-key distribution (QKD) is one of the most promising strategies for perfectly secure communication.Protocols based on entangled photon pairs are particularly attractive because of enhanced tolerance to losses and simplified generation of perfectly random secure keys. We use semiconductor-based sources of entangled photon pairs to implement QKD. Different from sources explored so far,...
Quantum systems based on cold atoms trapped in tweezer arrays are powerful analog simulators of the Hamiltonians they implement. Their experimental control has advanced to a point where they can be programmed to simulate a wide variety of physical systems. We report on a circuit- and gate-based description of cold atomic quantum simulators and how they integrate into a modern quantum computing...
We develop a framework (based on a recently studied framework of tensor decompositions) to decompose multivariate polynomials into univariate polynomials in a general way, explicitly expressing the polynomial's invariance. If the polynomial is contained in some positivity cone (for example sum of squares polynomials), we introduce and characterise corresponding inherently positive...
While a lot of effort has been made to understand the physical cause and effect relations, a general characterization of the ones that are, at least in principle, admissible by a logically consistent theory is still missing. With this poster I present the main ideas and formalisms that are used in this research direction, focusing both on the quantum and the classical case. The presentation is...
Transmon qubits require a large shunt capacitance to decrease the sensitivity to charge fluctuations. It is usually realized by very large capacitor plates, which increase the coherence due to decreased coupling to parasitic losses localized in material interfaces but it lowers the achievable integration density and increases parasitic cross coupling. We achieve the large capacitance by narrow...
Multipartite entanglement can be quantified by considering Local Operations assisted by Classical Communication (LOCC). However, for systems with fixed local dimensions, the partial order induced by LOCC is generically trivial. Consequently, we study a physically motivated extension of LOCC: multi-state LOCC. Here, one considers simultaneous LOCC transformations of finitely many pure states....
Despite their involved structure transformations via local operations assisted by classical communication (LOCC) are an active field of research due to their relevance to entanglement theory and their natural occurrence in communication scenarios.
However, generically no LOCC transformations are possible among multipartite pure states. Therefore, we focus in this work on entanglement classes...
Permutation-symmetric states are both mathematically interesting and physically relevant. To understand these states better, it is important to study their entanglement properties and the allowed transformations via local operations assisted by classical communication (LOCC) which are the free operators in the resource theory of entanglement. We characterize the stabilizers of a large class of...
We consider graph states under party-local Clifford transformations (PLC). Such transformations arise e.g. in quantum networks where shared entanglement between spatially close nodes complements local operations. Bravyi et al solved PLC equivalence of graph states for 3 parties via the introduction of an entanglement generating set (EGS), a finite set of states into a collection of which every...
In quantum computation, indefinite causal structures allow to perform certain tasks more efficiently than any conventional (causal) quantum algorithm. For example, the quantum switch can decide whether two unitary gates commute or anticommute with a single call to each gate, while in any causal quantum algorithm at least one gate has to be called twice. A generalization of this task to $n$...
Characterizing and controlling the coupling between qubits and environmental degrees of freedom is one of the central problems in quantum systems engineering. The coupling of one quantum system to multiple environmental degrees of freedom attracted significant attention during the last years both on theoretical and experimental sides, especially in the field of superconducting quantum...
We develop an optical technique to perform the quantum state tomography of a dipolar scatterer’s state of motion. We approach this problem by experimenting with trapped ions and trapped silica nanoparticle as levitated dipolar scatterers. By manipulating the light emitted by the scatterers, we aim to measure the position and the variance operators of the scatterer’s state of motion. This will...
Trapped ions are a well-established platform for analog or variational quantum simulation of quantum magnetism. Up to now, ions in linear Paul traps allow for simulations of the 1D Ising model with up to 50 spins. In our project, we aim for extending this approach to the second dimension which will enable studies of 2D non-equilibrium physics with a larger particle number (> 50). Here we...
The predissociation spectra of the $^{35}$Cl$^-$(H$_2$) and $^{35}$Cl$^-$(D$_2$) complexes are measured at low frequencies between 400 and 800 cm$^{-1}$ in an ion trap at different temperatures. Above a certain temperature, the ligand switching between the two isotopologues $ortho$ and $para$ leads to a strong suppression of the excited hyperfine configuration. Performing the experiment below...
The plasma sheath mechanisms are well-known in non-magnetised plasmas, but a model for a sheath in a tilted magnetic field does not exist. In this work, we present the development of a facility to study the sheath of RF plasmas in a tilted magnetic field. We aim at characterising the sheath by determining the potential, the electron and the ion temperatures and densities. To measure these...
Drift wave turbulence occurs ubiquitously in inhomogeneous magnetised plasmas, and determines transport in magnetic fusion experiments. The quasi two-dimensional turbulence implies an inverse energy cascade that condensates in persistent zonal flows, which correspond to a global sheared rotation in a torus. We study bifurcation from turbulence to flow regimes by simulations with a gyrofluid...
Gyrokinetic and gyrofluid models for magnetised plasmas evolve gyrocenter densities ne and ni of electrons and ions, that are coupled via a polarisation equation which determines the consistent electric potential phi fulfilling quasi-neutrality. Full-f models, based on the full distribution functions f without smallness assumptions of a Bousinesq approximation, use polarisation equations in...
Localised pressure perturbation "blobs" of plasma in a magnetic field with a field gradient grad B perpendicular to the field direction experience an interchange instability. The resulting propagation of a blob down the field gradient is similar to the Rayleigh-Taylor instability in neutral fluids, and contributes to intermittent losses in the outer scrape-off layer of fusion plasmas. We study...
The ASACUSA collaboration at CERN aims to perform a ppm measurement of the ground-state hyperfine structure of antihydrogen. Due to the Long Shutdown 2 no antiprotons are provided by CERN. For this reason, a proton source was developed to produce hydrogen by mixing electrons and protons in the same apparatus and with the same techniques which will be used for the antimatter experiment.
The...
The combination of crossed beams with kinematically complete velocity map imaging is a powerful tool to obtain experimental insight into reaction dynamics. The obtained differential cross sections can be linked to atomistic reaction mechanisms. We are investigating reactive scattering of CH$_3$I with atomic oxygen anions. Energy dependent experiments ranging from 0.4 eV to 2 eV relative...
The iron hydride cation (FeH+) is believed to be an abundant transition metal compound in the interstellar medium (ISM). Due to the lack of laboratory data, it has not been identified in spectral observations. We performed infrared multiple photon dissociation (IRMPD) spectroscopy of FeH+ tagged with two argon atoms. The Fe-H stretch in Ar2FeH+ is observed at 1854 cm-1, and two weaker...
Proton transfer reactions (PTR) are a useful means to detect volatile organic compounds in the atmosphere. By replacing the commonly used H$_3$O$^+$ with N$_2$H$^+$ or ArH$^+$ as the primary ion, an additional range of molecules becomes accessible for protonation, making PTR suitable for ultra-high purity (UHP) gas analysis.
Utilizing Fourier-transform ion cyclotron resonance (FT-ICR) mass...
In force spectroscopy of chemical bonds, single molecule chains are being stretched using an atomic force microscope (AFM). Strong surface anchors are required to address covalent bonds. Here acid chloride anchors are tested, featuring a very reactive functional group. Rupture force and rupture length of stretched polyethylene glycol was measured. The slope of the force curves is used to...
Plasma Fireballs are luminous, sharply defined, quasi-spherical plasma objects, which ap-pear in the vicinity of a positively biased electrode placed in background plasma, existing in both stable and dynamic states where a periodic expulsion and backflow of ions near the sheath edge is observed generating oscillations in the range of 20 kHz. In this work we present results on the study of the...
The gas-phase photophysics of complex biomolecules enable us to understand the intrinsic structural and functional properties without solvent influence. The photodetachment and photodissociation of deprotonated 2’-deoxyadenosine-5’-monophosphate anion (dAMP–), a monomer of DNA, contribute to its intrinsic photoresponse, fragmentation channels, and the associated lifetimes. We report on the...
Nanomedicine is quickly emerging field at the interface between nanotechnology and pharmacy with even some of the COVID-19 vaccines being prime examples. However, the microscopic imaging of these new technologies is lacking behind, causing a gap between practical application and theoretical understanding. In this poster, we present the results of characterizing protamine-microRNA nanoparticles...
Optical tweezers are a powerful tool for measuring tiny forces on the microscale. However, when multiple traps are used, it is challenging to simultaneously measure the individual forces and torques.
We present a generally applicable holographic force measurement method to recover the individual forces based on a single farfield image. As this method does not require information about size,...
In this contribution, a new experimental setup will be discussed which enables mass spectrometry and laser spectroscopy of (bio)molecular ions in a well-defined and ultracold environment. The setup consists of a helium nanodroplet (HND) source and an electrospray ionization (ESI) source in combination with a time-of-flight mass spectrometer. The ESI enables the transfer of fragile molecules...
Liquid crystal based spatial light modulators (LCoS SLMs) are widely used due to their ability to continuously modulate the phase of a light field. A common problem in these devices is the pixel crosstalk, which causes the response of the SLM to deviate from the ideal behaviour. We use detailed numerical simulations of the SLM to reproduce the measured response and model the crosstalk effect....
In general, 4D printing is a programmable deformation of the manufactured object over time, triggered by an external stimulus. For the sample production, a specially developed wood filament with a high sensitivity to moisture was used. Two different sample types having various print directions were designed and produced using an FDM 3D printer. As soon as the specimens came into contact with...
Disulfide bonds play an important role in biology, as they can influence the conformation of proteins through the covalent connection of adjacent strands. Reversible cleavage of the bond occurs both through physiological agents and forces. It is therefore interesting to study the effects of forces on the disulfide bond in the single molecule. For this purpose, we used an atomic force...
This work illustrates recent advances based on MicroScint, a technology aimed to realize a beam transverse profiler with high spatial resolution based on a microfluidic device. The active area consists in a silicon microfabricated structure filled with an organic liquid scintillator, with spatial resolution down to 30um. We also developed scintillating resin-based devices, obtained through...
Preparing the ground state of a Hamiltonian is a problem of great significance in physics with deep implications in the field of combinatorial optimization. We propose a variational quantum adiabatic algorithm (VQAA) for optimized adiabatic paths. We aim at combining the strengths of the adiabatic and the variational approaches for fast and high-fidelity ground state preparation. Our...
Treating reference frames as physical systems, subject to the
laws of quantum mechanics, they become quantum reference
frames. Located at the interplay of quantum and gravitational
physics, their treatment marks an essential step towards the
construction of a relational quantum theory. In this work, we
introduce a relational formalism which identifies coordinate
systems with elements of...
