17 November 2021

Iacopo Carusotto (Universitá di Trento)

Quantum Fluids of Light

In this colloquium, we will give an overview of the emerging field of quantum fluids of light: in the presence of a finite effective mass due to light confinement and binary interactions mediated by the optical nonlinearity of the material medium, an assembly of photons behaves as a fluid of particles and displays intriguing hydrodynamic phenomena.

After reviewing early work on Bose-Einstein condensation and superfluidity in such systems, I will sketch some among the most exciting recent developments at the crossroad of many-body physics, non-equilibrium statistical mechanics, and quantum optics.

The new features of topological lasing, aka non-equilibrium condensation into a topological edge mode, are capturing the interest of a wide community spanning across fundamental and applied research, from a remarkable topological protection of long-distance phase-locking to fabrication disorder to Kardar-Parisi-Zhang features in the emission coherence.

Strong efforts are presently devoted to the realization of strongly quantum correlated phases of photonic matter in a novel non-equilibrium context. After presenting recent realizations of Mott insulator and baby fractional quantum Hall fluids, I will sketch the new perspectives that these advances are opening for many-body physics and quantum technologies in general.

1 December 2021

Christopher Monahan (William & Mary)

Peering inside the proton

Calculating the internal three-dimensional structure of protons and neutrons has been a long-standing goal for nuclear physics. The strong nuclear force binds together quarks and gluons into protons, neutrons and other hadrons, but the strongly coupled nature of the strong force ensures that calculations of hadron structure are very challenging. Recent theoretical developments mean these calculations, using lattice quantum chromodynamics (QCD), have now become possible. Last year, the first proof-of-principle calculations of generalised parton distributions, which capture the correlations between the longitudinal momentum structure of nucleons and their transverse structure, marked the advent of a new era in lattice QCD calculations of hadron structure. I introduce the ideas that underpin these developments, and summarise some of the most exciting recent results.

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15 December 2021

Janet Anders (Exeter)

Quantum Brownian Motion for Magnets

In this talk I will discuss how a system+bath Hamiltonian, similar to the Caldeira-Leggett and spin-boson models, can be used to derive a general spin dynamics equation [1]. I will show how in the Ohmic (Markovian) limit the new equation reduces to the Landau Lifshitz Gilbert equation, a phenomenological equation widely used in magnetism. I will demonstrate how resonant Lorentzian couplings can be used as a general tool for the systematic comparison of spin dynamics of Markovian and non-Markovian regimes [1], and present numerical results of a classical spin's dynamics under classical and quantum noise.
In the second part of the talk we will explore long time steady states. The dynamical convergence to the Gibbs state is a standard assumption across much of classical and quantum thermodynamics. However, for nanoscale and quantum systems the interaction with their environment becomes non-negligible.  Is the system steady state then still the Gibbs state? And if not, how exactly does it depend on the interaction details? I will briefly outline several aspects of this timely topic [2, 3, 4].
[1] Quantum Brownian Motion for Magnets, 
J Anders, C Sait, S Horsley, arxiv 2009.00600 (2020).
[2] Weak and ultrastrong coupling limits of the quantum mean force Gibbs state, 
arXiv:2104.12606 to be published in PRL, JD Cresser, J Anders.
[3] Open quantum system dynamics and the mean force Gibbs state, 
arXiv:2110.01671, M Merkli, AS Trushechkin, JD Cresser, J Anders. 
[4] Quantum-classical transition of steady states and mean force Gibbs states in the spin boson model, 
in preparation, F Cerisola, M Berritta, S Scali, JD Cresser, SAR Horsley, J Anders.

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26 January 2022

Hannah Price (Birmingham)

Quantum Simulation with Synthetic Dimensions

In the field of quantum simulation, a quantum system, like a cold atomic gas, is artificially engineered so as to emulate phenomena such as topological phases of matter, which are now of great interest across many areas of physics. In this context, the concept of synthetic dimensions has emerged over the last decade as a powerful and general experimental approach. The main idea of a synthetic dimension is to couple together suitable degrees of freedom in order to mimic the motion of a particle along an extra spatial dimension. This approach provides a way to engineer controllable lattice models and to explore condensed-matter phenomena with different spatial dimensionalities. In this talk, I will give a brief overview of this topic, before presenting a very recent experiment to explore Bloch oscillations along a synthetic dimension of atomic trap states. I will then review how synthetic dimensions are used to implement topological models, before finally discussing perspectives for exploring physics with more than the usual three spatial dimensions. 

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9 February 2022

Tom Hayward (Sheffield)

From Stochasticity to Functionality: Harnessing Magnetic Domain Walls for Probabilistic and Neuromorphic Computing

Domain walls (DWs) in soft, ferromagnetic nanowires have been a topic of intense research interest due to proposals to use them as data carriers in energy efficient, non-volatile logic and memory devices. However, despite their apparent technological potential, these devices have been challenging to realise, because DWs pinning and propagation is highly stochastic, making digital devices unreliable [1]. While materials engineering approaches can be used to supress stochasticity [2], it is also interesting to consider whether alternative computer paradigms could prove more resistant to, or even benefit from, the DWs’ stochastic behaviours, thus converting it from a technologically inhibitive phenomenon into a functional property. 

 In this talk I will introduce the basic physical behaviours of domain walls in magnetic nanowires and show how these lead to complex and stochastic interactions between DWs and defect sites. I will then present a combination of experimental measurements and simulations that illustrate how these behaviours can be used to realise two different neuromorphic (brain-like) computing paradigms in hardware: feed-forward neural networks and reservoir computing [3]. The work presented will include experimental demonstrations of how these devices can be used to performed benchmark machine learning tasks such as spoken/written digit recognition.

 [1] T.J. Hayward and K.A. Omari, Beyond the quasi-particle: stochastic domain wall dynamics in soft ferromagnetic nanowires, Journal of Physics D: Applied Physics 50, 8, 084006 (2017).

[2] T.J. Broomhall, A.W. Rushforth, M.C. Rosamond, E.H. Linfield, and T.J. Hayward, Physical Review Applied 13, 024039 (2020).

[3] R. W. Dawidek, T. J. Hayward, I. T. Vidamour, T. J. Broomhall, M. Al Mamoori, A. Mullen, S. J. Kyle, P. W. Fry, N. J. Steinke, J. F. K. Cooper, F. Maccherozzi, S. S.Dhesi, L. Aballe, M. Foerster, J. Prat, E. Vasilaki, M. O. A. Ellis, D. A. Allwood, submitted to Advanced Functional Materials (2020).

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27 April 2022

Chandralekha Singh (Pittsburgh)

Facilitating thinking and learning in and beyond the physics classrooms using research-validated pedagogies and tools

I will discuss, using my research in physics education, how research can be used as a guide to develop curricula and pedagogies to reduce student difficulties. My research has focused on improving student understanding of introductory and advanced concepts, for example, in learning quantum mechanics.  We are developing research-validated learning tools such as tutorials and peer instruction tools that actively engage students in the learning process.  I will discuss how we evaluate their effectiveness using a variety of methodologies. I will also discuss our research studies that provide guidelines for how to enhance physics by making it equitable and inclusive.

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24 August 2022

Emily Nordmann (Glasgow)

The place and case for lectures and lecture capture in the new normal

In this talk I will discuss the evolution of research on lecture capture, from focusing on the links between recording live lectures and attendance, to integrating the use of recordings as a generic study skill, to the impact of providing recordings on widening participation and inclusivity. I will argue that the experience of the pivot to online due to covid has shown that lectures still have a place in the new normal and that the argument that lectures are not an effective way to learn only stands if the sole reason for lectures is to learn what the lecturer is teaching. that provide guidelines for how to enhance physics by making it equitable and inclusive.

31 August 2023

Niall Barr (Glasgow)

What a learning technology developer can do for you

In this talk I will introduce my role as a learning technology developer by describing some of my current and recent projects. These include YACRS, a classroom response system which was widely used at the University prior to lockdown, an experimental Adaptive Comparative Judgement (ACJ) tool, which has a lot of potential for both fair marking and peer evaluation, and, ErysNotes, a simple Python notebook application that runs on a fairly standard Web server, and which is particularly appropriate for introductory courses.

I will also describe some tools I have been working on to improve the efficiency and quality of teaching video production.

A major advantage of internally developed tools such as days is that they can be adapted to suit the needs of different lecturers relatively quickly, and are driven by pedagogy rather than marketing interests. I will be keen to hear any ideas for improvements to the existing tools. 

I will discuss how close collaboration between lecturers and the developer leads to significantly better outcomes for learning technology, and how working with the learning technology developer can also help the lecturer with Scholarship of Learning and Teaching (SoTL).

One of my areas of interest is interoperability standards for education, and I will also discuss how making use of open standards can improve sustainability and flexibility of educational material.