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Canonical Momenta in Digitized SU(2) Lattice Gauge Theory: Definition and Free Theory
Get PDFHamiltonian simulations of quantum systems require a finite-dimensional representation of the
operators acting on the Hilbert space H. Here we give a prescription for gauge links and canonical
momenta of an SU(2) gauge theory, such that the matrix representation of the former is diagonal
in H. This is achieved by discretising the sphere S3 isomorphic to SU(2) and the corresponding
directional derivatives. We show that the fundamental commutation relations are fulfilled up to
discretisation artefacts. Moreover, we directly construct the Casimir operator corresponding to the
Laplace-Beltrami operator on S3 and show that the spectrum of the free theory is reproduced again
up to discretisation effects. Qualitatively, these results do not depend on the specific discretisation
of SU(2), but the actual convergence rates do
Exploring the phase structure of the multi-flavor Schwinger model with quantum computing
Get PDFWe propose a variational quantum eigensolver suitable for exploring the phase structure of the
multi-flavor Schwinger model in the presence of a chemical potential. The parametric ansatz
circuit we design is capable of incorporating the symmetries of the model, present in certain
parameter regimes, which allows for reducing the number of variational parameters substantially.
Moreover, the ansatz circuit can be implementated on both measurement-based and circuit-based
quantum hardware. We numerically demonstrate that our ansatz circuit is able to capture the
phase structure of the model and allows for faithfully approximating the ground state. Our results
show that our approach is suitable for current intermediate-scale quantum hardware and can be
readily implemented on existing quantum devices
What is the purpose of student WhatsApp group communication: a speech act categorisation approach
Get PDFWalking through: nostalgia, Mythogeography and the Rural Dérive in Peter Riley’s Alstonefield
Get PDFLandscape poet Peter Riley uses the Situationist dérive in order to negotiate the cultural landscape of the British countryside, his collection Alstonefield (2002) forming a psychogeographic investigation into spaces of nostalgia, contradiction and pastoralism in British ruralism. This essay will argue that Riley adapts the urban dérive for a contemporary rural landscape, exploring the radicalisms of pastoral tropes and exposing the spectacle in British rural perceptions. Using the framework of Phil Smith Mythogeography, a contemporary theatrical adaption of the Situationist dérive, my aim is to explore the role of walking as a negotiation of rural spectacle within the wider Radical Landscape Poetry movement
Detecting and mitigating mode-collapse for flow-based sampling of lattice field theories
Get PDFWe study the consequences of mode-collapse of normalizing flows in the context of lattice field theory. Normalizing flows allow for independent sampling. For this reason, it is hoped that they can avoid the tunneling problem of local-update Markov Chain Monte Carlo algorithms for multimodal distributions. In this work, we first point out that the tunneling problem is also present for normalizing flows but is shifted from the sampling to the algorithm’s training phase. Specifically, normalizing flows often suffer from mode-collapse for which the training process assigns vanishingly low probability mass to relevant modes of the physical distribution. This may result in a significant bias when the flow is used as a sampler in a Markov-Chain or with importance sampling. We propose a metric to quantify the degree of mode-collapse and derive a bound on the resulting bias. Furthermore, we propose various mitigation strategies in particular in the context of estimating thermodynamic observables, such as the free energy
Derek Jarman’s Tempest, William Shakespeare’s Salò
Get PDFThis article re-evaluates Derek Jarman’s adaptation of William Shakespeare’s The Tempest (1979) based on archival research into the cinematic and historical intertexts that influenced the film. Specifically, it focuses on the impact of Pier Paolo Pasolini on Jarman’s aesthetics, particularly the Italian filmmaker’s last work: Salò, or the 120 Days of Sodom (1975). The article explores how Jarman used Pasolini’s work as a filter through which to frame his adaptation of Shakespeare’s play. In so doing, he produced a decidedly Pasolinian twist on The Tempest, which he explicitly referred to in his notes as “Shakespeare’s Salò.” Bridging the gap between the Renaissance and Jarman’s contemporary moment, Jarman’s film offers a meditation on ideas of captivity and captivation in The Tempest, which extends from the play and film’s literal representations of imprisonment to their exploration of the affective power of performance and spectacle
A Comparison of the Reactivity of the Lattice Nitrogen in Tungsten Substituted Co3Mo3N and Ni2Mo3N
Get PDFBio-Inspired Multi-Objective Algorithms Applied on the Optimisation of the AODV's Routing Recovery Mechanism
Get PDFAdvances in electronic systems, wireless communication protocols, and intelligent devices allowed the development of networks of mobile devices such as cars, drones, and robots. The field of mobile ad hoc networks (MANETs) comprises networks where the mobility of the devices is one of the fundamental elements that characterise these networks. However, the node’s mobility leads to constant changes in the network’s topology, representing a challenge to routing protocols designed for MANETs. Although there is effort from researchers to tackle the intricacies of routing protocols in MANETs, there is still room for improvement as new applications with challenging specifications continue to arise. This research enriches the existing theoretical perspective by presenting an innovative method for optimising the routing performance of the ad hoc on-demand distance vector (AODV) protocol. Grounded on multi-objective metaheuristics, we aim to improve AODV’s routing recovery performance concerning routing delay, energy consumption, packet loss ratio, and route load metrics. To gauge the quality of our contribution, we compare its performance to the standard AODV, a mono-objective optimised AODV, and four other well-known routing protocols with different routing approaches. The results indicate that the proposed solution was superior to the original AODV with average improvements of 56.0%, 59.3%, 48.1% and 0.7% on route load, routing delay, packet loss ratio and energy consumption, respectively. It also presented competitive results compared to other routing protocols
Malta: The Roots of a Polarised Media System
Get PDFMalta is a state with a high level of political parallelism and polarisation, a country which is exceptional in that it has the highest amount of social media engagement, coupled with the highest level of distrust of news organisations within the EU. Yet, this is a country which has the highest general electoral turnout in the World. I investigate the historic roots which lead to this position and postulate its relevance to a broader global audience. I show that an advocacy tradition has been ever present and has value which enhances the country’s levels of pluralism and democratic credentials. The political context in which Maltese journalists operate is presented and moves to probe and acquire an insight into the electoral system, how it enhances polarisation and has pushed the main political parties to own and champion their media houses