Wed 05 Feb 16:15: Exploring Quantum Phases of Matter on Quantum Processors
Quantum fluctuations and interactions give rise to exotic phases of matter with remarkable properties, pushing the boundaries of our understanding of many-body quantum systems. Solving these problems is notoriously difficult on classical computers due to the exponential complexity of quantum many-body physics. Quantum processors, however, open new avenues for exploring these systems, offering a direct and potentially transformative approach. In this talk, I will first outline recent progress in realizing and studying topologically ordered and symmetry-protected phases using quantum hardware. I will then discuss their intriguing dynamical properties and how these can reveal quantum phase transitions. Finally, I will introduce a class of novel, highly entangled quantum phases that exist only in non-equilibrium settings and demonstrate how to probe their stability using a quantum processor.
- Speaker: Frank Pollmann (TU Munich)
- Wednesday 05 February 2025, 16:15-17:15
- Venue: Small Lecture Theatre, Cavendish Laboratory, J.J. Thomson Avenue.
- Series: Cavendish Quantum Colloquium; organiser: Lucas Sá.
Wed 05 Feb 13:30: Cryptography, quantum computers and analytic number theory
The security of many widely used communication systems hinges on the presumed difficulty of factoring integers or computing discrete logarithms. However, Shor’s celebrated algorithm from 1994 demonstrated that quantum computers can perform these tasks in polynomial time. In 2023, Regev proposed an even faster quantum algorithm for factoring integers. Unfortunately, the correctness of his new method is conditional on an ad hoc number-theoretic conjecture. Using tools from analytic number theory, we establish a result in the direction of Regev’s conjecture. This enables us to design a provably correct quantum algorithm for factoring and solving the discrete logarithm problem, whose efficiency is comparable to Regev’s approach.
In the first part of this talk, we will provide an accessible overview of these developments and their place within the broader context of cryptography. The discussion will require no prior background as we will cover the necessary concepts, including a brief introduction to quantum computing from a mathematician’s perspective.
The second part of the talk will focus on the number-theoretic aspects of this work. We will outline the proof of a variant of Regev’s conjecture, using lattice techniques, character sums and zero-density estimates for Dirichlet L-functions.
- Speaker: Cédric Pilatte (University of Oxford)
- Wednesday 05 February 2025, 13:30-15:00
- Venue: MR4, CMS.
- Series: Discrete Analysis Seminar; organiser: Julia Wolf.
Fri 02 May 16:00: TBA
Abstract not available
- Speaker: Mrinal Dasgupta (Manchester U.)
- Friday 02 May 2025, 16:00-17:00
- Venue: MR19 (Potter Room, Pavilion B), CMS.
- Series: HEP phenomenology joint Cavendish-DAMTP seminar; organiser: Terry Generet.
Fri 21 Feb 16:00: TBA
Abstract not available
- Speaker: Rene Poncelet (Cracow, INP)
- Friday 21 February 2025, 16:00-17:00
- Venue: MR19 (Potter Room, Pavilion B), CMS.
- Series: HEP phenomenology joint Cavendish-DAMTP seminar; organiser: Terry Generet.
Wed 29 Jan 13:30: Lower bounds for incidences and Heilbronn's triangle problem
Upper bounds on the number of incidences between points and lines, tubes, and other geometric objects, have many applications in combinatorics and analysis. On the other hand, much less is known about lower bounds. We prove a general lower bound for the number of incidences between points and tubes in the plane under a natural spacing condition. In particular, if you take n points in the unit square and draw a line through each point, then there is a non-trivial point-line pair with distance at most n-2/3+o(1). This quickly implies that any n points in the unit square define a triangle of area at most n-7/6+o(1), giving a new upper bound for the Heilbronn’s triangle problem. Joint work with Alex Cohen and Cosmin Pohoata.
- Speaker: Dmitrii Zakharov (Massachusetts Institute of Technology)
- Wednesday 29 January 2025, 13:30-15:00
- Venue: MR4, CMS.
- Series: Discrete Analysis Seminar; organiser: Julia Wolf.
Fri 24 Jan 13:00: Geometric Characterizations of Kerr-de Sitter and Related Metrics in All Dimensions
The Kerr-de Sitter metric, originally proposed by Carter in four dimensions and later extended by Gibbons, Lü, Page and Pope to all dimensions, is likely to play a relevant role among Lambda positive vacuum spacetimes. To better understand what makes it special, we calculate the asymptotic data characterizing the metric near conformal infinity. This requires a review of tools in conformal geometry, such as the Fefferman-Graham expansion, and its relation with the asymptotic initial value problem in arbitrary dimensions. The asymptotic data obtained for Kerr-de Sitter admits a straightforward generalization to a broader class of spacetimes that depends on a set of parameters, which we refer to as Kerr-de Sitter-like class. This class of metrics is obtained explicitly as limits or analytic extensions of Kerr-de Sitter and the space of parameters inherits a natural topological structure from the asymptotic data. Furthermore, we discuss additional characterizations within the Kerr-Schild type metrics and the algebraically special metrics that highlight the geometrical significance of the class.
- Speaker: Carlos Peón Nieto (UPM, Madrid)
- Friday 24 January 2025, 13:00-14:00
- Venue: Potter Room / https://cam-ac-uk.zoom.us/j/84511154241?pwd=B778JtHEd8Vb7aTOdsygQhBdXWbybI.1.
- Series: DAMTP Friday GR Seminar; organiser: Daniela Cors.
Fri 31 Jan 14:00: Understanding Battery Function - New Metrologies, New Chemistries and New Insights
14:00-15:00 – three 20 minute presentations from early career researcher working on ‘energy’:
Dr Joshua Lawrence ‘Disentangling thylakoid membrane energy conversion with electrochemistry’
Ms Xinyu Liu ‘Structural disorder determines capacitance in nanoporous carbons’
Dr Sayan Kar ‘Solar-powered air-to-fuel synthesis for a circular carbon economy’
15:30-16:30 – Keynote Lecture by Prof Dame Clare Grey FRS (Geoffrey Moorhouse Gibson Professor of Chemistry) ‘Understanding battery function – new metrologies, new chemistries and new insights’.
Rechargeable batteries have been an integral part of the portable electronics revolution and are now playing a critical role in transport and grid applications to help mitigate climate change. However, these applications come with different sets of challenges. New technologies are being investigated and fundamental science is key to producing non-incremental advances and to develop new strategies for energy storage and conversion.
This talk will focus on our own work to develop NMR , MRI and new optical methods that allow devices to be probed while they are operating, from the local, to particle and then cell level. This allows transformations of the various cell materials to be followed under realistic conditions without having to disassemble and take apart the cell. Starting with local structure and dynamics, as measured by NMR , I will then show – with the optical methods – how the different dynamics can result in different intercalation mechanisms. A good example is our work on LiCoO2, where via optical approaches we were able to directly visualize movement of phase fronts as lithium is removed and inserted into this material. I will discuss our work on the application of electron spin resonance and dynamic nuclear polarization (DNP) NMR to graphitic anode materials and lithium metal batteries, to understand battery degradation. Finally, new results on extremely high-rate batteries will be outlined and extensions of our new metrologies to study a wider range of electrochemical systems will be described.
- Speaker: Professor Dame Clare P. Grey, FRS, DBE + 3 Researcher Presentations
- Friday 31 January 2025, 14:00-16:30
- Venue: Dept of Chemistry, (BMS) Bristol Myers Squibb Lecture Theatre.
- Series: Chemistry Departmental-wide lectures; organiser: Xani Thorman.
Wed 05 Feb 14:30: Modelling Excited State Processes in Molecular Crystals
The study of photoexcitations in molecular aggregates faces the twofold problem of the increased computational cost associated with excited states and the complexity of the interactions among the constituent monomers. A mechanistic investigation of these processes requires the analysis of the intermolecular interactions, the effect of the environment, and 3D arrangements or crystal packing on the excited states. A considerable number of techniques have been tailored to navigate these obstacles; however, they are usually restricted to in-house codes and thus require a disproportionate effort to adopt by researchers approaching the field. In this talk, I will describe some techniques implemented in our group to investigate excited state processes in molecular crystals, considering electrostatic embedding approaches and their use for studying nonadiabatic dynamics. I will showcase a recent application for studying singlet fission in the pentacene crystal.
- Speaker: Dr Rachel Crespo-Otero, University College London
- Wednesday 05 February 2025, 14:30-15:30
- Venue: Unilever Lecture Theatre, Yusuf Hamied Department of Chemistry.
- Series: Theory - Chemistry Research Interest Group; organiser: Lisa Masters.
Wed 12 Feb 14:30: Functional interfaces in UHV and in water : recent insights from ab initio
In this lecture I will illustrate some examples of complex and reactive interfaces that remain poorly defined at the atomic scale, which are simulated using two standard approaches in quantum chemistry, i.e. static DFT in vacuum and DFT -MD in water to explicitly treat the solvent. In nanoscience and UHV , atomic force microscopes are increasingly using molecular tips, such as the CO molecule. I’ll describe a recent example studied in collaboration with J. Kröger’s team at Ilmenau (Germany), where the CO tip becomes an active probe that interacts differentially with phthalocyanines before and after metallization and/or dehydrogenation. Another example of complex interfaces is the case of 2D materials such as graphene and also its ‘commercial’ counterpart – graphene oxide (GO) – immersed in an aqueous solvent for applications in water filtration and remediation. In both cases, realistic modeling of these interfaces has revealed unexpected chemical reactivities, enabling us to recover certain properties measured in nanofluidics.
- Speaker: Professor Marie-Laure Bocquet, Ecole Normale Supérieure
- Wednesday 12 February 2025, 14:30-15:30
- Venue: Unilever Lecture Theatre, Yusuf Hamied Department of Chemistry.
- Series: Theory - Chemistry Research Interest Group; organiser: Lisa Masters.
Wed 05 Mar 16:30: TBC
TBC
- Speaker: Charles Senecal, University of Cambridge
- Wednesday 05 March 2025, 16:30-17:30
- Venue: MR12.
- Series: Algebra and Representation Theory Seminar; organiser: Adam Jones.
Wed 12 Feb 16:30: TBC
TBC
- Speaker: Zachary Feng, University of Oxford
- Wednesday 12 February 2025, 16:30-17:30
- Venue: MR12.
- Series: Algebra and Representation Theory Seminar; organiser: Adam Jones.
Wed 05 Feb 16:30: Unipotent representations in the local Langlands correspondence
The local Langlands correspondence (LLC) is a kaleidoscope of conjectures relating local Galois theory, complex Lie theory, and representations of p-adic groups. This talk will give an introduction to the part of the LLC involving unipotent representations. Reducing modulo p, we can move from representations of p-adic groups to representations of finite reductive groups, which have a rich structure developed by Deligne—Lusztig. I will talk about joint work with Anne-Marie Aubert and Dan Ciubotaru in which we lift some of this structure to p-adic groups. I will not assume previous familiarity with these topics; instead I’ll give an introduction to these ideas via examples.
- Speaker: Beth Romano, King's College London
- Wednesday 05 February 2025, 16:30-17:30
- Venue: MR12.
- Series: Algebra and Representation Theory Seminar; organiser: Adam Jones.
Tue 04 Feb 11:00: The Proton EDM experiment
The storage ring proton electric dipole moment (EDM) experiment (pEDM) will be the first direct search for a proton EDM and will improve on the current (indirect) limit by 5 orders of magnitude. It will therefore surpass the current sensitivity (set by neutron EDM experiments) to QCD CP -violation by 3 orders of magnitude, making it potentially the most promising effort to solve the strong CP problem. This makes it manifestly one of the most important probes for the existence of axions (with important consequences for dark matter searches), CP-violation in the Higgs sector and the source of the universe’s matter-antimatter asymmetry. These, coupled with a new Physics reach of O(10^3) TeV and a construction cost of O(£100M), make it one of the low-cost/high-return proposals in particle physics today. The experiment will build upon the highly successful techniques of the Muon g-2 Experiment at Fermilab, which the UK has been a leading contributor to. In this talk, I will motivate and describe the pEDM experiment, and detail how the UK can play a leading role in making it a success by building upon its vast expertise and recent achievements.
- Speaker: Alex Keshavarzi, University of Manchester
- Tuesday 04 February 2025, 11:00-12:00
- Venue: Ryle Seminar Room.
- Series: Cavendish HEP Seminars; organiser: Dr Paul Swallow.
Tue 28 Jan 11:00: GScan’s industrial tracker system for the muon tomography applications
This presentation will discuss the development and production of the GScan detector systems, as well as its performance in tomographic measurements. We will highlight the system’s spatial resolution, material classification capabilities, and its potential to revolutionize various industries.
GScan’s technology can detect objects and chemical changes up to 10 meters deep in critical infrastructure with millimetre accuracy. This is achieved by combining muon tomography and AI/ML. Muon tomography utilises harmless, highly penetrative cosmic ray origin muons to create 3D images of large objects, such as historical pyramids, modern bridges, tunnels, mining sites, industrial systems, and nuclear reactors.
GScan’s muonFLUX detector system, developed in collaboration with the University of Cambridge, UCLouvain, Imperial College London, DLR and DESY in Germany, and CERN , is designed for scalable production and diverse applications. Despite its compact, solid, and lightweight design, the system achieves 120 μm spatial and 1 mrad angular resolution in track reconstruction, allowing for the differentiation of objects composed of low-Z materials. Its compact, lightweight, robust and transportable nature makes it suitable for commercial use, especially outdoor and mobile applications.
This presentation will discuss the development, production, and performance of the GScan detector in tomographic measurements, highlighting its spatial resolution, material classification capabilities, and potential to revolutionize various industries.
- Speaker: Andi Hektor, GScan
- Tuesday 28 January 2025, 11:00-12:00
- Venue: Ryle Seminar Room.
- Series: Cavendish HEP Seminars; organiser: Dr. Aashaq Shah.
Tue 11 Mar 11:00: Search for hadronic resonances below 100 GeV with ATLAS
Many proposed models of physics beyond the Standard Model predict new resonances. In particular, searches for resonances decaying into hadrons can probe any resonances that may be produced at the LHC . However, such dijet searches lose sensitivity at low masses due to transverse momentum trigger thresholds. This talk presents a recent ATLAS search for such low mass resonances using the invariant mass spectrum of large-radius (R=1) jets with two-pronged substructure. The jets recoil against an energetic photon from initial state radiation, which is used as a trigger, thus avoiding the issue of jet trigger thresholds. The large radius jets are clustered from inner detector tracks and narrow (R=0.2) calorimeter jets. Narrow jets are calibrated using a new in-situ method. Dedicated uncertainties on the energy scale and – resolution of these jets are derived and propagated to the large-radius jets. This enables a consistent calibration down to the lowest masses probed in the search. These techniques enable the search for boosted hadronically decaying resonances in the mass range 20-100 GeV hitherto unprobed by the ATLAS Collaboration. The observed data are found to agree with Standard Model predictions and 95% confidence level upper limits are set on the coupling of a hypothetical new spin-1 Z′ resonance with Standard Model quarks as a function of the assumed Z′-boson mass in the range between 20 and 200 GeV.
- Speaker: Lars Henkelmann
- Tuesday 11 March 2025, 11:00-12:00
- Venue: Ryle Seminar Room.
- Series: Cavendish HEP Seminars; organiser: Dr Paul Swallow.
Tue 04 Mar 11:00: Bound and Entangled: Adventures at the TTbar Threshold
TBC : Basics of Quantum information, the recent ATLAS entanglement result, a CMS entanglement result, and toponium “observations”.
- Speaker: Ethan Simpson, University of Manchester
- Tuesday 04 March 2025, 11:00-12:00
- Venue: Ryle Seminar Room.
- Series: Cavendish HEP Seminars; organiser: Dr Paul Swallow.
Tue 25 Feb 11:00: Title to be confirmed
TBC
- Speaker: Jerimiah Mitchell, University of Cambridge
- Tuesday 25 February 2025, 11:00-12:00
- Venue: Ryle Seminar Room.
- Series: Cavendish HEP Seminars; organiser: Dr Paul Swallow.
Tue 18 Feb 11:00: Title to be confirmed
TBC :
- Speaker: Laura Fabbri, University of Bologna
- Tuesday 18 February 2025, 11:00-12:00
- Venue: Ryle Seminar Room.
- Series: Cavendish HEP Seminars; organiser: Dr. Aashaq Shah.
Tue 11 Feb 11:00: Title to be confirmed
TBC : AI applications to medical imaging in cancer research
- Speaker: Lorena Escudero
- Tuesday 11 February 2025, 11:00-12:00
- Venue: Ryle Seminar Room.
- Series: Cavendish HEP Seminars; organiser: Dr. Aashaq Shah.
Tue 04 Feb 11:00: Title to be confirmed
TBC - Proton EDM experiment
- Speaker: Alex Keshavarzi, University of Manchester
- Tuesday 04 February 2025, 11:00-12:00
- Venue: Ryle Seminar Room.
- Series: Cavendish HEP Seminars; organiser: Dr Paul Swallow.