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Particle, condensed matter and quantum physics: links via Maxwell's equations

Event

Location

Kavli Royal Society Centre, Chicheley Hall, Newport Pagnell, Buckinghamshire, MK16 9JJ

Overview

Satellite meeting organised by Professor Anatoly Zayats, Professor John Ellis CBE FRS and Professor Roy Pike FRS

The electromagnetic field distribution above a plasmonic crystal. Credit: Daniel O’Connor and Ryan McCarron, King’s College London

Event details

Maxwell’s equations unify electricity and magnetism and link research in all modern physics. This meeting will provide in‐depth discussions of the state of the art and inter‐relations between the fields of high-energy physics, experimental and theoretical condensed matter and quantum physics so as to explore common themes and analogies between them, exposing young researchers to connections between current developments in these fields.

Abstracts will be made available shortly.

draft programme is available to download and recorded audio of the presentations will be available on this page after the event.

Attending this event

This is a invitation only residential conference, which allows for increased discussion and networking.  It is free to attend, however participants need to cover their accommodation and catering costs if required.

Enquiries: Contact the events team

Participants are also encouraged to attend the related scientific discussion meeting which immediately precedes this event.


Event organisers

Select an organiser for more information

Schedule of talks

18 November

09:00-13:15

Session 1: Maxwell and the universe

6 talks Show detail Hide detail

Chairs

Professor John Ellis CBE FRS, Kings College London, UK

09:05-09:30 Isolated photons, dressed electrons and jets: defining the final state in high energy collisions

Professor Jonathan Butterworth, UCL, UK

Abstract

At particle colliders, the energy is such that to a good approximation the products of a collision can often be treated as bullet-like particles, and Feynman diagrams treated as probabilities, rather than amplitudes. But clear definitions of observables remain vital to reduce model dependence and achieve the best precision - as well as being desirable in principle. I will discuss some of the issues around this - some of which are resolved, and some of which are the subject of active debate.

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09:30-10:00 The MOeDAL experiment at LHC: broadening the LHC horizons

Professor Nick Mavromatos, King's College London, UK

Abstract

In the talk I will review the current physics programme of the MoEDAL experiment at Point 8 of the Large Hadron Collider (LHC) ring at CERN (Switzerland). This experiment, which has resumed full operation recently, after LHC started its second run after the long shut down, is the seventh and newest LHC experiment. The experiment is dedicated to the search for highly ionizing particle avatars of physics beyond the Standard Model, extending signi ficantly the discovery horizon of the LHC. Slowly moving, highly ionising particles that could signal new physics at the LHC-run-II energies of up to 14 TeV, include, among others, long-lived charged supersymmetry partners of ordinary matter that are predicted to exist in supersymmetric extensions of the standard model, new types of quarks, termed ``quirks'', which are bound together in hadronic structures but through a new kind of strong forces, and of course monopole-like magnetically charged particles, of masses in the range 4-7 TeV/c^2 = (7 - 16) x 10^{-24} Kg (termed ``electroweak monopoles'') , that have been predicted to exist in some modifications of the standard model. In view of the nature of this meeting, I will put the emphasis of my review on a brief description of the theory behind such monopole-like configurations, their production mechanisms at LHC energies and the corresponding MoEDAL searches, which are largely complementary to the corresponding programs of the large multipurpose LHC detectors ATLAS and CMS.

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11:00-11:30 Maxwell in one equation, at home in space-time

Professor Anthony Lasenby, University of Cambridge, UK

Abstract

The subject of this talk is the link between Maxwell's equations and Clifford Algebra. The latter entered mainstream physics via the Pauli and Dirac algebras in the 1920s, but it is less commonly known that the Maxwell equations themselves can benefit from being written in a Clifford Algebra form. The simplest form of the equations is achieved in a more recent version of Clifford Algebra called Geometric Algebra (GA), which was pioneered by David Hestenes in the 1960s. GA provides a unified mathematical language spanning complex numbers, quaternions, spinors, and the tensors of general relativity, and providing for each a home in the geometric algebra of spacetime. Applied to the Maxwell equations, it allows them to be written in a single compact equation, and in a form which displays clearly its relation with other wave equations of relativistic physics, such as the neutrino and Dirac equations. The benefits of the new form are not just cosmetic, but suggest new solution approaches, and the example of radiation from a moving charge will be discussed, where the GA approach provides one of the most compact (and intuitively useful) expressions for the radiated fields so far found.

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11:30-11:45 Finite-energy electroweak monopoles at the LHC

Dr Tevong You, University of Cambridge, UK

Abstract

Monopole configurations in the Standard Model have infinite energy and are therefore not physical. One possibility to obtain a finite mass monopole is to embed the Standard Model SU(2)xU(1) into a semi-simple group. Alternatively the Standard Model may be modified by a non-minimal Higgs coupling whose form is chosen to regularize the infinite energy. A finite-energy electroweak monopole compatible with Higgs measurements is constructed.

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11:45-12:00 Magnetic current and new modifications of Maxwell's equations

Mr Mehdi Nosrati, University of Alberta, Canada

Abstract

Maxwell’s equations are the main foundation of current communication technology; however, given certain ambiguities and unknown parameters, they are still incomplete. Magnetic current is apparently the main crucial missing component of these equations. In this talk, we will resolve to revise these equations as well as the conventional definitions of the terms and parameters from the beginning, basing ourselves merely on logical theory to justify all measurements made so far. These revisions will be initiated by modifying Bohr’s Model and the physical differentiations of magnetic and electrical charges and fluxes in order to justify all electromagnetic phenomena under a consistent umbrella. Consequently, we can theoretically present a rational illustration of magnetic current and amend the contradictions and inconsistencies in the current models and theory of electromagnetic waves. Furthermore, a question is put forward to determine whether we can go beyond Maxwell’s equations. In order to answer this question some rational justifications, confirmed with measurements, will be presented which demonstrate that we can propagate the wave inside a metallic waveguide merely by using a magnetic field without generating an electrical field. Finally, a general question is put forward asking the gravity can be linked to electromagnetic forces or not. Criticizing the Standard Model and String theory, a different hypothetical model is presented to justify the gravity based on the proposal theory.

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12:30-13:00 Higgs Physics at the Run2 LHC

Dr Veronica Sanz, University of Sussex, UK

Abstract

A way to search for new physics is to look for deviations in Higgs and electroweak production. This talk explains how to do this in detail in the context of an Effective Theory approach. It will be shown how a global fit of LEP and LHC Run1 data has constrained new physics participating in the electroweak sector to a level that is competitive and complementary to direct searches for new states and move onto the prospects for discovery at Run2 LHC.

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13:15-14:15

Lunch

14:15-17:15

Session 2: Maxwell and condensed matter

5 talks Show detail Hide detail

Chairs

Dr Joe Bhaseen, King’s College London, UK

14:15-14:30 Emergent coulomb physics in Heisenberg spin liquids

Dr Jorge Rehn, Max Planck Institute for the Physics of Complex Systems, Germany

Abstract

Condensed matter systems exhibit a richness of possible ground states, with some carrying excitations with unique properties otherwise not shared by the elementary particles in nature. A particular class of geometrically frustrated spin models is known to exhibit excitations that much alike mimics the behavior of Coulomb charges. At low temperatures these systems are described by an emergent gauge field, with spin configurations mapped to configurations statistically described by a field governed by a magnetostatic action. These so-called classical Coulomb spin liquids were up to now known to exist only in models whose concomintant gauge-charged excitations live on a bipartite lattice.

The situation where the charges occupy the sites of a non-bipartite lattice was hitherto unknown, and in this talk a model with emergent charges on a triangular lattice will be presented. This has interesting new consequences for observable physical phenomena, and goes along with a novel mapping to a gauge field. Dilution of this system produces disorder nucleated 'vector' charges that are fractionalized objects carrying 1/3 of the moment of the original spins in the model, making this perhaps the first instance of a classical spin system exhibiting fractionalization into 3 objects. A zero temperature effective theory for these fractionalized, Coulomb vector charges, will be presented, which represents a new kind of Coulomb spin model presenting a glassy phase.

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14:30-14:45 A study of the effect of curvature on near-field radiative heat transfer

Dr Karthik Sasihithlu, Imperial College London, UK

Abstract

Electromagnetic wave-effects become important in radiative heat exchange between two bodies when they are separated by gaps less than wavelength of light. When the two bodies support surface modes which can be thermally excited, the enhanced near-field radiative transfer due to photon tunnelling can exceed the classical blackbody limit by several orders of magnitude. While the dependence of near-field radiative transfer on the gap between two planar objects is well understood, the effect of curvature on near-field radiative transfer is unclear. In particular, the relevance of an approximate method (called proximity approximation) to predict the near-field interaction between curved bodies is disputed. Hence, the exact computation of near-field radiative transfer between curved bodies, such as between two spherical bodies, become important. This computation is based on a first-principles derivation using vector spherical wave expansion method which is commonly employed to analyse electromagnetic scattering problems in spherical coordinates. In this talk, drawbacks in current methods to compute the radiative transfer between the spherical bodies are discussed, and a simplified form of the coefficients of vector translation theorem is shown which enables computation of radiative heat transfer for nanoscale gaps. Based on the analysis of results, a modified form of proximity approximation method is also proposed to resolve the discrepancy between theoretical predictions and experimental observations.

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14:45-15:00 Graphene, plasmons and transformation optics

Dr Paloma Huidobro, Imperial College London, UK

Abstract

The optical, and consequently, plasmonic properties of graphene (an atomic-thick honeycomb lattice of carbon atoms) can be controlled by external means such as a gate voltage, and for this reason graphene has attracted a lot of attention as a highly versatile plasmonic material. Plasmons in graphene feature a deep subwavelength confinement together with a strong enhancement of the electromagnetic fields, which can be employed to increase the low optical absorption of this 2D material having a great potentiality for graphene-based optoelectronics.

In this contribution Dr Huidobro uses transformation optics to study plasmons in graphene excited with the help of subwavelength dielectric gratings. The potential of transformation optics, which has successfully provided analytical solutions to various problems in plasmonics, resides in its ability to relate highly symmetric structures to more complex ones. Here they consider gratings formed by a periodic modulation of graphene’s conductivity, as well as this together with a subwavelength dielectric grating of the same periodicity placed close to the graphene sheet. In both cases, the shape of the periodic profiles derive from a conformal transformation that maps a Cartesian mesh into a wavy and periodic one, and they can be accurately approximated to a sinusoidal shape. It shows coupling to highly confined graphene surface plasmons that provide very large field enhancements, thus increasing the low optical absorption of graphene. For the case of periodic modulation of the conductivity they discuss the optimal conditions for coupling into the surface plasmons.

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16:00-16:30 From Einstein-Maxwell to quantum transport

Dr Joe Bhaseen, King’s College London, UK

Abstract

Recently there has been a great deal of interest in the possible applications of gauge-gravity duality to condensed matter problems. This talk will discuss applications of these holographic techniques to strongly correlated systems. The methods provide unifying links between different domains of physics, including gauge theories, gravity, fluid dynamics and quantum mechanics.

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16:45-17:15 The history of Maxwell’s equations

Basil Mahon

Abstract

Maxwell’s equations have been called the Mona Lisa of physics. Simple, elegant and powerful, they encapsulate the laws of electromagnetism, which, 150 years ago, opened the door to hitherto undreamt of regions of scientific knowledge. As Albert Einstein put it, these laws marked the end of one scientific epoch and the start of another (our own). Richard Feynman was in no doubt that future historians will judge Maxwell’s discovery to be the most significant event of the nineteenth century.

Basil Mahon will show that the emergence of these wonderful equations owes as much to the experimental genius of Michael Faraday as to the theoretical genius of Maxwell. By creating the entirely new concept of the electromagnetic field, the two men made it possible for scientists to break free from the strictly mechanical view of the physical world which had prevailed since Newton’s time. Maxwell’s theory was so different from anything that had gone before that none of his contemporaries really understood it, and several decades passed before the theory gained acceptance. Basil Mahon will discuss the factors that brought this acceptance about, including the contribution of Oliver Heaviside.   

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19 November

09:00-12:30

Session 3: Maxwell and electromagnetism

6 talks Show detail Hide detail

Chairs

Professor Anatoly Zayats, King's College London, UK

09:00-09:30 Electromagnetic doughnuts: localised and propagating toroidal excitations

Professor Nikolay Zheludev, University of Southampton, UK

Abstract

Recent progress in toroidal electrodynamics that has been possible with artificial metamaterials will be reviewed. The toroidal dipole is a localised electromagnetic excitation independent from the familiar magnetic and electric dipoles. While the electric dipole can be understood as separated opposite charges and the magnetic dipole as a current loop, the toroidal dipole introduced by Y. B. Zaldovich in 1958 it corresponds to currents flowing on the surface of a torus. Resonant interactions of induced toroidal dipoles with electromagnetic waves have recently been observed in metamaterial structures at microwave, terahertz and optical frequencies. They provide distinct and physically significant contributions to the basic characteristics of matter including absorption, dispersion, and optical activity, the origin of which cannot be comprehensively interpreted in the context of standard multipoles alone. Interference of radiating induced toroidal and electric dipoles leads to transparency windows in artificial materials as a manifestation of the dynamic anapole. Toroidal excitations also exist in free-space as spatially and temporally localised electromagnetic pulses propagating at the speed of light and interacting with matter.

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09:30-09:45 Near-field terahertz spectroscopy: studying terahertz resonators on a micro-scale

Dr Irinia Khromova, King's College London, UK

Abstract

Terahertz radiation allows for non-destructive detection of objects and processes ’invisible’ at optical and microwave frequencies. Modern terahertz science promises break-through security, medical, and quality control techniques, as well as access to crucial astronomical observation and environmental monitoring. However, the emerging terahertz technology is held back by the scarcity of functional materials and devices required for manipulation of terahertz radiation.

This talk demonstrates opportunities and advantages of the near-field terahertz time-domain spectroscopy for direct studies of terahertz electromagnetic resonances occurring on a micrometre scale. As examples of micro-resonators, it considers conductive micro-fibres and dielectric micro-spheres. Micro-resonators are at the heart of numerous promising terahertz solutions, including the metamaterial approach – creating functional materials from artificial pre-designed resonant micrometre-sized ‘meta-atoms’. Experimental studies of micrometre-scale terahertz resonances are essential, yet inaccessible to common far-field spectroscopic techniques due to extreme sensitivity requirements.

This non-contact technique maps the field patterns of terahertz resonant modes excited in individual conductive or insulating micro-objects, and gives access to essential parameters of micro-resonators, including their resonance frequency, local field enhancement and quality factors. Depending on the underlying physics of observed terahertz resonances, it allows for material and structural characterisation of micro-objects.

This work uses the examples of carbon micro-fibres and titanium dioxide micro-spheres to show the advantages of near-field terahertz time-domain spectroscopy for non-contact terahertz conductivity probing and anisotropic material characterisation; and direct observation of versatile resonant modes, including surface-plasmon resonances in conductive dipoles, and magnetic dipole resonances in dielectric subwavelength terahertz resonators.

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09:45-10:00 Transformation optics applied to electron-loss problems in plasmonics

Mr Matthias Kraft, Imperial College London, UK

Abstract

Transformation optics is a relatively new subfield in electromagnetic research. Yet, it has been at the heart of many of the most promising advancements in electromagnetism in recent years. Originally developed to aid numerical simulations in cylindrical geometries, it has since been applied as a design tool for such exotic devices as invisibility cloaks or negative refractive index lenses. Within the last 5 years, transformation optics has entered the field of plasmonics. It has proved valuable as a design tool for devices such as beam shifters, surface cloaks or light harvesters. Moreover, it has also proven itself as an analytical tool in the study of interacting plasmonic nano-particles or van der Waals forces. This talk would like to add an entry to the already long list of fields where transformation optics can make a difference. The study of electron energy loss spectroscopy of plasmonic nano-particles.

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11:00-11:30 From spinning fields to chiral optical forces

Dr Cyriaque Genet, ISIS - University of Strasbourg and CNRS, France

Abstract

Direct manipulation of particles through light-induced forces has led to formidable progress, which has been impacting research in many areas ranging from ultracold-matter physics to biology. The rise of nano-optics has offered the experimentalists new types of optical excitations associated with inhomogeneous fields and complex beam topologies that lead to a great variety of dynamical effects. It was pointed out recently that light radiation pressure is determined by the sole orbital part of the Poynting vector, with no contribution from its spin part. This has important consequences that can be clearly illustrated in the context of surface plasmon optics. The intrinsic spinning character of a plasmonic field brings indeed a clear dynamical distinction between orbital and spin energy flows that can be readily discussed in terms of induced optical forces and torques. Simultaneously, the interest focuses on exploiting the connections between spin-orbit interaction and the concept of chirality at the level of the plasmonic near field. These connections have direct fundamental implications with new possibilities opened in the context of chirality. In particular, new types of optical forces have been recently unveiled when a chiral object is illuminated by a chiral light field that can lead to new chiral separation and discrimination schemes. Such new effects and schemes will be presented and discussed when aiming at manipulating chiral nano-objects using tailored chiral optical fields.

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11:30-11:45 Spin Hall effects in photonics

Dr Francisco Rodríguez-Fortuño, King's College London, UK

Abstract

Scalar waves can be uniquely described by their amplitude and phase distributions through space; while the amplitude determines the position, the phase distribution determines the propagation direction (wave-vector) of the waves. In addition to those spatial degrees of freedom, electromagnetic waves, being described by vector fields, also posses polarization degrees of freedom, determined by the directions in which the electric and magnetic fields oscillate with time. Spin-orbit interactions of light describe how, under certain circumstances, the polarization of light can affect its propagation direction. This coupling between the spatial and polarization degrees of freedom is completely described by Maxwell's equations applied to the appropriate geometry, and can be analogous to spin-orbit interactions of relativistic quantum particles and electrons in solids. After mentioning some general examples, this talk will focus on a novel kind of spin-orbit interaction that arises on near fields, which are associated with an elliptical or circular polarization in the electric and/or magnetic fields, and can be exploited for an extremely robust polarization-controlled nano-routing of electromagnetic waves in a wide range of scenarios. Experimental examples in different platforms will be described, as well as the reciprocal scenario, in which light propagation can be used to synthesize polarizations.

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11:45-12:00 Multipoles, spherical t-designs and polarization state reconstruction

Dr Matthew Foreman, Max Planck Institute for the Science of Light, Germany

Abstract

Measurement of the polarisation state of light is a common problem in many branches of fundamental and applied science. Accurate and robust measurements are essential in all such applications. Recently, interest has grown in determining higher order polarisation properties, as these can play a key role in nonlinear and quantum processes. Whilst polarisation dependent optical nonlinear processes can provide important insights into crystal and molecular structure, higher order properties described through a multipolar expansion of the polarisation matrix can contain “hidden” polarisation correlations, which are of interest both in a quantum and in a classical context.

Optimisation of linear polarisation measurements is well studied, however, the problem of optimally reconstructing higher order polarisation properties has to date remained unsolved. The authors present their recent work in which they derive an analytic solution to this problem using an arbitrary number of measurements. Their analysis hence generalises existing results in the linear domain which have been predominately confined to minimal measurement sets, however, critically the authors present optimal measurement strategies for higher order problems. The presented method employs the elegant mathematical framework of spherical t-designs, thereby the derived optimal measurement sets constitute a powerful generalisation of the concept of mutually unbiased bases.

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12:30-13:30

Lunch

13:30-17:30

Session 4: Maxwell and quantum

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Chairs

Professor Roy Pike FRS, King's College London, UK

13:30-14:00 Can we make a spin qubit activated switch for lossless quantum photonic circuits?

Dr Ruth Oulton, University of Bristol, UK

Abstract

Lossless switches for single photons are a key element in photonic quantum circuits for quantum information processing and quantum simulations.  One requires that, dependent on the state of one quantum bit (qubit), one may switch the logic state of another qubit.   Essentially, this would require the state of one photon to switch another photon (for example from horizontal to vertical polarisation). For photons, this process is impossible to achieve deterministically (i.e. predictably without loss) without a very strongly non-linear material. Dr Oulton will discuss that this strong non-linearity may come from the interaction with a single quantum emitter.  She will outline how a trapped electron spin in a quantum dot, a nanosized region of semiconductor, may be used to achieve this strong non-linearity.  Dr Oulton will then go on to discuss how photonic structures surrounding the quantum dot may be used to increase the interaction strength, discussing previous approaches using high quality factor optical cavities.  Before explaining that these high quality factor structures, which are difficult to manufacture, are perhaps not necessary and that present, easily fabricated structures may be used, bringing the lossless single photon switch closer to reality.

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14:00-14:15 Quantum information processing with photons in dielectric circuits

Dr Pieter Kok, University of Sheffield, UK

Abstract

Scalable quantum technologies require faithful conversion between matter qubits storing the quantum information and photonic qubits carrying the information in integrated circuits and waveguides. In this talk I show how photons generated by quantum dots in waveguides can be manipulated to create a variety of resources necessary for scalable quantum technologies.

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14:15-14:30 Light-matter interactions for scalable quantum photonics

Dr Josh Nunn, University of Oxford, UK

Abstract

The high frequency of optical signals makes them ideal carriers of classical and quantum information, capable of supporting large alphabets and high data rates over long distances, with zero thermal noise even at room temperature. It has long been known that optics could provide a route to large scale quantum information processing in ambient conditions. But despite advances in waveguide and detector technology, large scale quantum photonics remains impossible because logic operations and quantum correlations can only be generated probabilistically. Here I will describe how coherently driven media can be used to modify propagating light fields to overcome this scalability challenge.

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15:30-16:00 Photonic contributions to quantum technology

Sir Peter Knight FRS, Imperial College London, UK

Abstract

Quantum Physics has focused on light, matter and their interaction, from the early days of quantum mechanics right down to the present day. Much of this work has concentrated on the nature of quantum correlations beyond what is allowed classically. Although understanding the duality of wave and particle challenges our classical intuition, one cannot escape asking hard questions on this issue, and indeed this subject was at the heart of Bohr-Einstein debate in the early years of the 20th century.  The emergence of quantum optics and especially studies of the nature of nonclassical light and its exploitation in quantum computing and quantum cryptography have put this back at the heart of current physics Progress in identifying, generating and characterizing nonclassical states has been spectacular. Quantum Information Science in part has grown out of this progress: the quantum world allows information to be encoded, manipulated and transmitted in ways quite different from classical physics. This paper will discuss the formation, propagation and manipulation of single photon wavepackets, explain how these can be used in simple quantum networks (for example in quantum walks and in Boson Sampling), and describe recent work on detecting single photons non-destructively.

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16:15-17:00 Panel discussion

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Particle, condensed matter and quantum physics: links via Maxwell's equations Kavli Royal Society Centre, Chicheley Hall Newport Pagnell Buckinghamshire MK16 9JJ