• G.G. Marion, van

FotU Members Presenting at Physics@Veldhoven 2022

At this year's digital Physics@Velhoven event, four FotU members will be presenting their posters. They will be online Wednesday 26-01-2022 between 13:20 and 14:20 for anyone registered for the event to ask questions about their research. Let's see what their posters are all about.


 

Jann Aschersleben will be presenting:

Event reconstruction using pattern spectra and machine learning for the Cherenkov Telescope Array


The Cherenkov Telescope Array (CTA) will be the next generation gamma-ray observatory and will be the major global instrument for very-high-energy astronomy over the next decade, offering 5 - 10 x better flux sensitivity than current generation gamma-ray telescopes. Each telescope will provide a snapshot of gamma-ray induced particle showers by capturing the induced Cherenkov emission at ground level. The simulation of such events provides images that can be used as training data for convolutional neural networks (CNNs) to determine the energy of the initial gamma rays. Analyses based on CNNs promise to further enhance the performance to be achieved by CTA, compared to other state-of-the-art algorithms. Pattern spectra are commonly used tools for image classification and provide the distributions of the shapes and sizes of various objects comprising an image. The use of relatively shallow CNNs on pattern spectra would automatically select relevant combinations of features within an image, taking advantage of the 2D nature of pattern spectra. In this work, we generate pattern spectra from simulated gamma-ray events instead of using the raw images themselves in order to train our CNN for energy reconstruction. This is different from other relevant learning and feature selection methods that have been tried in the past. Thereby, we aim to obtain a significantly faster and less computationally intensive algorithm, with minimal loss of performance.


 

Martine Schut will be presenting:

Improving resilience of the quantum gravity induced entanglement of masses (QGEM) against decoherence using 3 superpositions


A recently proposed quantum gravity induced entanglement of masses (QGEM) protocol for testing the quantum nature of a graviton uses the entanglement of 2 qubits. The entanglement can arise only if the force between the two spatially superposed masses is occurring via the exchange of a mediating virtual graviton. In this paper, we examine a possible improvement of the QGEM setup by introducing a third qubit. We compare the entanglement generation for different experimental setups with 2 and 3 qubits and find that a 3-qubit setup where the superpositions are parallel to each other leads to the highest rate of entanglement generation within τ = 5 s. We show that the 3-qubit setup is more resilient to the higher rate of decoherence. The entanglement can be detected experimentally for the 2-qubit setup if the decoherence rate γ is γ<0.11 Hz compared to γ<0.16 Hz for the 3-qubit setup. However, the introduction of an extra qubit means that more measurements are required to characterize entanglement in an experiment. We conduct experimental simulations and estimate the number of measurements needed to detect the entanglement in the QGEM protocol at 99.9% certainty. For γ> 0.06 Hz the 3-qubit setup is favourable compared to the 2-qubit setup in terms of the minimum number of measurements needed to characterize the entanglement. Thus, the proposed setup here provides a promising new avenue for implementing the QGEM experiment.


 

Eric Pap will be presenting:

Exceptional points in adiabatic quantum mechanics


In adiabatic quantum mechanics, the phenomenon of Berry/geometric phase is well-known for Hermitian Hamiltonians. The phase corresponds to parallel transport on a bundle of eigenstates. However, this standard theory does not apply to non-Hermitian Hamiltonians, which govern open quantum systems. The problem comes from non-cyclic states: states that return with a different energy, even though all system parameters are restored to their original values. These exchanges of energies and states occur around specific degeneracies, known as exceptional points. We describe a framework that generalizes the standard theory to include these non-cyclic states.


 

Gianni van Marion will be presenting:

Applying transition state theory to sphaleron transitions


Transition state theory (TST) helps us under-stand chemical reactions and their rates. Itexamines the excited state (``activated com-plex'') of the barrier separating the reactantsfrom products. The state is associated with adividing surface; The rate being linked with the flux through it.

Sphaleron transitions are a process in gauge field theory that conceptually resemble chemical reactions. They are of interest in the study of the universe's matter-antimatter asymmetry. Their rates are usually computed by path integral (PI)means.

This begs the question: Can TST be used to com-pute these sphaleron rates? This poster dis-cusses our research on this issue: It gives anintroduction to TST using classical normal form(CNF) methods and shares the results of ournumerical application of it to a particular fieldtheory. These results show that CNF-TST is con-sistent with the conventional PI approach.


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