Previous Niels Bohr Lectures

 

SPECIAL Niels Bohr Lecture by Howard Stone, Princeton University

15. okt. 2024, kl. 10.30

Soft materials, from biofluid mechanics to molecular biology

Abstract: Modern research questions in fields centered around biology, from molecular biology to bioengineering and biophysics, often require for their solution understanding of physical chemistry, the physics of soft materials, and the out-of-equilibrium conceptual framework that is part of classical mechanics, including hydrodynamics.

In this talk, I will try to sketch some of the ways in which classical concepts, extended to be applicable to the conditions relevant to biologically inspired questions, offer new insights.

We will touch on several themes, from larger than the scale of a cell to smaller than the scale of cell. For example, our studies have demonstrated, respectively, changes in wettability that can enable bacterial transport in porous materials, surface-attached bacterial cells that can “twitch” upstream in a channel flow, and that there can be transcriptional modifications that accompany swimming cells in channel flows.

Moreover, the modern revolution in sub-cellular biological condensates can be usefully viewed from the lens of physical chemistry and mechanics.

I will provide some examples and then show the link of condensates to the formation of the spindle in a dividing cell, which is a fundamental aspect of molecular biology.

Finally, if there is time, new ideas regarding the use of molecular rotors for measuring the viscosity of biological membranes will be explained. The work summarized above is drawn from many collaborations that I have had, including recently and back ten or so years.

Niels Bohr Lecture by Drummond Fielding, Cornell University

9. okt. 2024, kl. 16.15

Bridging the Divide: A Multi-Scale Approach to Galaxy Formation

Galaxies are at the core of nearly all modern astrophysical studies. They serve as essential cosmological probes, tracing the structure of the universe, while also providing the stage on which stars form and black holes grow. Despite their incredible importance, our understanding of galaxy evolution remains far from complete.

There are fundamental inconsistencies between our best models and observations. The key piece in this cosmic puzzle lies in deciphering the complex balance between the inflows and outflows that shape galaxies and regulate the fuel supply for their continued growth.

Understanding these galactic gas flows has, to date, been inhibited by the seemingly insurmountable range of spatial and temporal scales inherent to the governing processes.

I will describe recent efforts to bridge this vast range of scales and illuminate the principles underlying galaxy formation using novel simulations that connect small-scale processes, like atomic cooling and turbulent mixing, with larger-scale phenomena, such as supernova explosions and cosmological structure formation.

Our new model points to an intuitive picture that aims to reconcile the tension at the heart of galaxy formation.

Niels Bohr Lecture by Andreas Wallraff

12. juni 2024, kl. 16.15

­­Loophole-free Bell Inequality Violation with Superconducting Circuits*

Andreas Wallraff: Department of Physics, ETH Zurich, Switzerland

Abstract: Superposition, entanglement, and non-locality constitute fundamental features of quantum physics. Remarkably, the fact that quantum physics does not follow the principle of locality can be experimentally demonstrated in Bell tests performed on pairs of spatially separated, entangled quantum systems.

While Bell tests were explored over the past 50 years, only relatively recently experiments free of so-called loopholes succeeded. Here, we demonstrate a loophole-free violation of Bell’s inequality with superconducting circuits [1].

To evaluate a CHSH-type Bell inequality, we deterministically entangle a pair of qubits and perform fast, and high-fidelity measurements along randomly chosen bases on the qubits connected through a cryogenic link spanning 30 meters. Evaluating more than one million experimental trials, we find an average S-value of 2.0747 ± 0.0033, violating Bell’s inequality by more than 22 standard deviations.

Our work demonstrates that non-locality is a viable new resource in quantum information technology realized with superconducting circuits with applications in quantum communication, quantum computing and fundamental physics.

Niels Bohr Lecture by Vincenzo Vitelli

29. maj 2024, kl. 16.15

Odd Turbulence

Abstract: Fully developed turbulence is a universal and scale-invariant chaotic state characterized by an energy cascade from large to small scales where the cascade is eventually arrested by dissipation.

In this talk, we discuss how to harness these seemingly structureless turbulent cascades to generate patterns. Pattern formation entails a process of wavelength selection, which can typically be traced to the linear instability of a homogeneous state.

By contrast, the mechanism we propose here is fully non-linear. It is triggered by a non-dissipative arrest of turbulent cascades: energy piles up at an intermediate scale, which is neither the system size nor the smallest scales at which energy is dissipated. Using a combination of theory and large-scale simulations, we show that the tunable wavelength of these cascade-induced patterns can be set by a non-dissipative transport coefficient called odd or gyro viscosity.

This non-dissipative viscosity is ubiquitous in chiral systems ranging from plasma and bio-active media to quantum fluids. Cascade-induced patterns could also occur in natural systems including atmospheric flows, stellar plasma such as the solar wind, as well as the pulverization of objects or the coagulation of droplets where mass rather than energy cascades.

Niels Bohr Lecture by Thomas Hertog

15. maj 2024, kl. 16.15

On the Origin of Time

Abstract: Perhaps the biggest question Stephen Hawking tried to answer in his extraordinary career was how the universe could have created conditions so perfectly hospitable to life. Pondering this mystery led him to study the big bang origin, but his early work ran into a crisis when the math predicted many big bangs producing many universes, most far too bizarre to harbor life. 

Holed up in theoretical physics departments across the globe, Hawking and I worked shoulder to shoulder for twenty years, to develop a fresh vision of the universe’s birth that could account for its mysterious biophilic design. At the heart of our cosmogony lies a novel quantum framework for early universe cosmology that predicts that time and indeed physics itself fade away back into the big bang, leading to a Darwinian-like perspective on cosmogenesis.

In this colloquium I recount our quest to get a grips on the origin of time, and the bold new take on some of the universe’s fundamentals we have been led to. 

Niels Bohr Lecture by Erwin Frey

8. maj 2024, kl. 16.15

Emergence and Self-Organisation in Biological Systems

Abstract: Isolated systems tend to evolve towards thermal equilibrium, a special state that has been a research focus in physics for more than a century. By contrast, most processes studied in living and life-like systems are driven and far from thermal equilibrium.

A fundamental overarching hallmark of all these processes is the emergence of structure, order, and information, and we are facing the major challenge of identifying the underlying physical principles.

Two exciting problems are the self-organised formation of spatio-temporal patterns and the robust self-assembly of complex structures. In both fields, there have been recent advances in understanding the underlying physics that will be reviewed in this talk.

Niels Bohr Lecture by Collin Broholm

17. april 2024, kl. 16.15

Quantum fluctuations on triangular lattices of Ising spins

Abstract: In the quest to chart qualitatively new states of matter, frustrated magnets offer a variety of opportunities. A frustrated magnet is a crystalline solid where the leading interactions between atomic magnetic moments are incompatible with an ordered magnetic state. The result is a degenerate manifold of spin configurations from which novel collective states of matter can emerge. I shall describe our use of magnetic neutron scattering to characterize these and to determine the frustrated interactions for deep engagement with quantum many body theory.

The particular example I focus on is the triangular lattice of spins-1/2 with uniaxial (Ising) antiferromagnetic interactions, which indeed has finite entropy at . In the cobalt based model systems that we have examined [1], weak transverse interactions introduce quantum fluctuations that lift this degeneracy and produce a rich magnetic phase diagram. We provide experimental evidence for compressible (gapless) and incompressible (gap-full) phases with spontaneous translational and rotational symmetry breaking. We associate the gapless phases near zero and full magnetization with super-solid states of hard core bosons on the triangular lattice.

Niels Bohr Lecture by Immanuel Bloch

10. april 2024, kl. 16.15

Quantum Simulations with Atoms, Molecules and Photons.

Abstract: 40 years ago, Richard Feynman outlined his vision of a quantum computer for quantum simulations of complex calculations of physical problems.

Today, his dream of analog and digital quantum simulations has become a reality and a highly active field of research across different platforms ranging from ultracold atoms and ions, to superconducting qubits and photons.

In my talk, I will outline how ultracold atoms in optical lattices started this vibrant and interdisciplinary research field 20 years ago and now allow probing quantum many-body phases in- and out-of-equilibrium with fundamentally new tools and single particle resolution and control.

Novel (hidden) order parameters, entanglement properties, full counting statistics or topological features can now be measured routinely and provide deep new insight into the world of correlated quantum matter.

I will introduce the measurement and control techniques in these systems and delineate recent applications regarding quantum simulations of strongly correlated electronic systems.

Niels Bohr Lecture by Mark Lancaster

20. marts 2024, kl. 16.15

Title: Is new physics hiding in the magnetic interactions of a muon?

Abstract: The interaction of a muon’s spin with a magnetic field defines its magnetic moment in terms of the gyromagnetic ratio, g. In the Dirac equation, g is exactly 2, but additional higher order QED, electroweak and strong interactions increase its value by ~ 0.1%. Moreover, new interactions beyond the Standard Model of particle physics can also contribute at the level of approximately 1 part per million. Very precise measurements are thus required to uncover new, beyond the Standard Model, interactions.

I will describe the most recent, world's best, measurement, from the Fermilab Muon g-2 experiment: a measurement with a precision of 0.2 parts per million which is the most accurately measured quantity using a particle accelerator storage ring and the plans to improve this precision and the Standard Model calculation which will hopefully resolve whether the magnetic interaction of a muon is a harbinger of new physics or not.

Niels Bohr Lecture by Mark Saffman

31. jan. 2024, kl. 16.15

ABCs of Rydberg physics: from Atoms to Bottles to Computers

Abstract: One hundred years ago Quantum Mechanics was invented and applied first to understanding the structure of atoms. A hundred years later, the tables have turned, and atoms are a tool for gaining a deeper understanding of quantum mysteries.

Arrays of atoms with interactions provided by highly excited Rydberg states provide a setting where atomic physics takes on extreme properties which are being harnessed for quantum applications. In the last few years remarkable progress has been achieved with neutral atom arrays, and they are now established as a leading platform for quantum information processing. 

In this talk I will delve into aspects of Rydberg physics that endow these highly excited atoms with remarkable properties and show how we can trap, control, and program their quantum states.

Niels Bohr Lecture by Nicola Spaldin

24. jan. 2024, kl. 16.15

Title: Hunting for Hidden Order

Abstract: Most magnetic materials, phenomena and devices are well described in terms of their constituent magnetic dipoles. There is mounting evidence, however, that higher-order magnetic multipoles can lead to intriguing magnetic behaviors, which are often attributed to "hidden order" since they are difficult to characterize with conventional probes. 

In this talk I will focus on the existence and relevance of the so-called magnetoelectric multipoles, which form the next-order term, after the magnetic dipole, in the multipolar expansion of the energy of a magnetization density in a magnetic field. 

I will describe how magnetoelectric multipoles underlie multiferroic behavior and dominate the magnetic response to applied electric fields, then discuss signatures of hidden magnetoelectric multipolar order and possibilities for its direct measurement.

I will argue that all is not lost if your material lacks magnetoelectric multipoles, and that hidden magnetic octupoles and even triakontadipoles also cause fascinating physics, including the currently rather fashionable "altermagnetism". 

Finally, I will show that ferroic ordering of these higher-order magnetic multipoles results in a magnetization at the surface of a sample, even in materials with no net magnetization in their bulk and with apparently compensated surface dipoles.  

 

 

Niels Bohr Lecture by Anne L’Huillier

  1. dec. 2023, kl. 16.15

L'Huillier was awarded the Nobel Prize in Physics in 2023, along with Pierre Agostini and Ferenc Krausz, for their work on "experimental methods that generate attosecond pulses of light for the study of electron dynamics in matter." 

Anne L'Huillier, professor of atomic physics at Lund University in Sweden, receives 1/3 of this year’s Nobel prize for her groundbreaking work on attosecond physics, which has had a profound impact on our understanding of the microscopic world.

Prof. L'Huilliers 1987 discovery of high-harmonic generation in infrared laser light transmitted through a noble gas has laid the ground for a new era of atomic spectroscopy, providing a wealth of new insights into the rapid dynamics of electrons inside atoms and molecules.

Her research has also led to numerous practical applications, such as new types of lasers and medical diagnostic tools.

In this Niels Bohr Lecture, Prof. L’Huillier will give her own personal account of the discovery and the exciting physics being uncovered within the realm of attosecond spectroscopy.

Niels Bohr Lecture by Michael Freedman

  1. juni 2023, kl. 16.30

Title: Squares and Square roots in social economics and physics

Abstract: There is a school of social thought originating in Lionel Penrose’s 1946 proposal of “quadratic voting” that seems to be evolving both toward ideas of Kant and Leibniz in philosophy and making contact with the Born rule from quantum mechanics.

I’ll discuss what I know and don’t know about these developments. 

Niels Bohr Lecture by L. Mahadevan, Harvard University

  1. juni 2023, kl. 16.15
  2. Mahadevan has made a career out of exploring the science behind everyday phenomena, like the shape of an apple or how the brain folds.

Title: The wisdom of the swarm

Abstract: Super-organisms such as social insects solve complex physiological problems collectively, sans plan or planner, on scales much larger than the individual.

Motivated by observations in the field and in the lab, I will describe our attempts to understand how insects actively engineer their micro-environment in such contexts as termite mound morphogenesis, active ventilation and mechanical stabilization in bee clusters, and collective construction in ants. 

By linking physics and behavior on multiple scales using local sensing and action mediated by global physics, these examples point to a kind of embodied physical intelligence.  

To synthesize these complex collective behaviors, I will close by describing our experiments using simple robots that sharpen some questions raised a long time ago by Tinbergen, among others. 

Niels Bohr Lecture by Jörg Schmalian, Karlsruhe Institute of Technology

  1. maj 2023, kl. 16.15

Title: Superconductivity without Quasiparticles

Abstract: Superconductivity is abundant near quantum-critical points, where fluctuations suppress the formation of Fermi liquid quasiparticles and the Bardeen-Cooper-Schrieffer theory no longer applies.

Holographic superconductivity, rooted in the duality of quantum field theory and gravity theory, has been proposed to describe such systems.

We derive holographic superconductivity in form of a gravity theory with emergent space-time from a quantum many-body Hamiltonian.

Niels Bohr Lecture by professor Mike Cates, University of Cambridge

  1. marts 2023, kl. 16.15

Surprises in the statistical physics of active matter

Talk by: Professor Mike Cates, University of Cambridge

Abstract: Statistical physics was invented to describe the macroscopic properties of large numbers of particles. It has a hidden weakness: almost all of its results depend on the microscopic forces being reversible. That is, the forces are assumed to derive from a Hamiltonian, or energy function, which governs both the microscopic mechanics and the equilibrium probability distribution (the Boltzmann distribution).

This is why mechanical quantities like pressure are not only time averages of forces (on a wall) but also thermodynamic state functions (which exist independently of any wall).

Active matter systems are different. Their particles take energy out of the environment, and use it for self-propulsion; the resulting dissipation breaks microscopic time-reversal symmetry. Examples include swimming micro-organisms, and synthetic colloids propelled by optical or chemical energy. In such cases there is no Hamiltonian: the usual connection between interaction forces and macroscopic behaviour is broken.

I will describe recent advances in statistical physics for active matter systems, focussing on some of their surprising properties, such as the following. (i) Random motion in a bath of active particles can be globally rectified into a steady current by introducing inert, asymmetric obstacles. (ii) Fluid-fluid phase separation can arise among active particles in the complete absence of the attractive interactions that cause this in equilibrium. (iii) The pressure of an active fluid on a wall is not a state function -- it depends on the type of wall. (iv) Various interfacial phenomena, governed in equilibrium by a single surface tension, now depend on several distinct tensions, which need not all be positive.

Niels Bohr Lecture by Michelangelo Mangano, CERN

  1. febr. 2023, kl. 15.15

Title: Physics at the LHC: the legacy so far, and beyond

Abstract: Particle physics is engaged in a worldwide effort to deepen our understanding of key issues, from the origin of dark matter and neutrino masses, to the dynamics of electroweak symmetry breaking and of non-perturbative strong interactions.

A diverse collection of facilities and experiments, in the laboratory, in the sky and underground, in addition to theoretical work, are mobilized in these efforts. In this framework, collider experiments play a special role.

The results of the Large Hadron Collider so far allow us to further optimize the exploration of the landscape unveiled by the discovery of the Higgs, and by the continued resilience of the Standard Model.

Precision is emerging as a new theme, bringing new theoretical and experimental challenges, and providing unanticipated discovery opportunities.

The searches for phenomena beyond the Standard Model are also acquiring a new intrinsic value, as they contribute to consolidate the robustness of the theory and the accuracy of its modeling.

The talk will present the vision for the future of the Large Hadron Collider and of a next generation of colliders.

Niels Bohr Lecture by Netta Engelhardt, MIT

  1. jan. 2023, kl. 16.15

The Black Hole Information Paradox in the Age of Holographic Entanglement Entropy and Complexity

Abstract: The black hole information paradox — whether information escapes an evaporating black hole or not —  remains one of the greatest unsolved mysteries of theoretical physics.

The apparent conflict between validity of semiclassical gravity at low energies and unitarity of quantum mechanics has long been expected to find its resolution in the deep quantum gravity regime.

Recent developments in the holographic dictionary and in particular its application to entanglement and complexity, however, have shown that a semiclassical analysis of gravitational physics has a hallmark feature of unitary evolution.

I will describe this recent progress and discuss some promising indications of a resolution of the information paradox.

 

 

Niels Bohr Lecture by Sharon Weiner and Zia Mian from Princeton University

  1. nov. 2022, kl. 15.00

Nuclear Weapons in the 21st Century: Challenges and prospects

Talk by: Sharon Weiner and Zia Mian, Princeton University

Abstract:  The threat of use of nuclear weapons has shadowed Russia's war against Ukraine and according to US President Joe Biden raised the prospect of escalation to nuclear war to the highest level in 60 years.

This crisis comes at a time of intensifying great power competition, and nuclear weapon modernization plans which include more roles for nuclear weapons, more types of weapons, and if allowed to prevail will insure nuclear weapons remain a threat to the end of the 21st century.

In contrast, informed by the transboundary and long lasting humanitarian consequences of nuclear weapon use, most of the world has embraced a security future without nuclear weapons, and many  countries and global civil society support the 2017 UN treaty to prohibit these weapons.

This two-part colloquium will address current US nuclear policy processes and debates, which are central to the dynamics of the international nuclear order, and the new framework provided by the Treaty on The Prohibition of Nuclear Weapons.

Niels Bohr Lecture by Chris Hays, Oxford University

  1. juni 2022, kl. 14.15

High-precision measurement of the W boson mass with the CDF II detector

Talk by: Professor Chris Hays, Oxford University

Abstract: The mass of the W boson, a mediator of the weak force between elementary particles, is tightly constrained by the symmetries of the standard model of particle physics. The Higgs boson was the last missing component of the model. After the observation of the Higgs boson, a measurement of the W boson mass provides a stringent test of the model. We measure the W boson mass using data corresponding to 8.8 inverse femtobarns of integrated luminosity collected in proton-antiproton collisions at a 1.96 TeV center-of-mass energy with the CDF II detector at the Fermilab Tevatron collider.

Niels Bohr Lecture by professor Vladan Vuletić

  1. maj 2022, kl. 15.30

Search for Dark Matter with Atomic Precision Spectroscopy

Niels Bohr Lecture by professor Vladan Vuletić, Massachusetts Institute of Technology, USA

Abstract: The Standard Model of particle physics describes virtually all measurements of elementary particles exquisitely well, and yet various astrophysical evidence points to new physics beyond the Standard Model.

Recently it has been proposed to search for particles outside the Standard Model in an intermediate mass range (100 eV to 100 MeV) by means of precision isotope shift spectroscopy on narrow optical transitions. The exquisite precision of optical spectroscopy allows one to access high-energy physics with experiments at the eV scale.

We report two nonlinearities in so-called King plots of measured isotope shifts for trapped Yb+ ions. Such nonlinearities can indicate physics beyond the Standard Model, or be due to higher-order nuclear effects within the Standard Model.

We also discuss how future more precise measurements on more transitions, in combination with improved atomic-structure calculations, can be used to distinguish between effects within and outside the Standard Model.

Niels Bohr Lecture by Professor Christof Wetterich

  1. maj 2022, kl. 15.15

Quantum gravity from the beginning to the present Universe

Talk by: Professor Christof Wetterich,  theoretical physics at Heidelberg University

Abstract: A realistic evolution of our Universe needs to extend Einstein‘s general relativity by some form of dark energy. Dark energy governs the beginning epoch ( inflationary cosmology) and the present late cosmology.

A scalar field with appropriate properties of its potential can describe both inflation and dynamical dark energy. The metric fluctuations in quantum gravity determine important characteristics of this potential. From pure conceptual thinking quantum gravity turns to observable predictions. The Universe is found to be eternal, beginning in the infinite past with great emptiness.

 

 

Niels Bohr Lecture by professor Amina Helmi

  1. marts 2020, kl. 15.30

New views on the Galaxy from the Gaia space mission

Talk by: Professor Amina Helmi, Kapteyn Astronomical Institute in Groningen

Abstract: The recent 2nd data release of the Gaia mission is revolutionizing our understanding of the Milky Way and its constituents. In this talk, I will highlight a few of the results stemming from the analysis of this truly spectacular dataset. In particular, I will focus on what we have learned about the dynamics and assembly of the Milky Way thus far. 

Niels Bohr Lecture by professor Bruce D. Gaulin

  1. jan. 2020, kl. 15.15

Geometric Frustration and Quantum States of Matter in Pyrochlore Magnets

Talk by: Professor Bruce D. Gaulin, McMaster University, Ontario, Canada.

Abstract: Most matter exhibits disordered states at high temperature and ordered states at low temperatures.  However competition among the interactions between the constituent atoms or magnetic moments in solids can forestall or preclude ordered states of matter, even at low temperatures, if it is sufficiently strong.  Nature provides many examples of geomerically-frustrated magnets; magnets whose crystalline architecture is based on networks of triangles and tetrahedra, where such competition can be a natural consequence of the local geometry.  

We, and others, have been interested in exploring magnetic ground state selection in a family of cubic magnetic insulators, known as pyrochlores, whose magnetic moments decorate a three-dimensional network of corner-sharing tetrahedra.  Different magnetic ground states can be selected at ~ zero temperature depending on the properties of the magnetic moments themselves and the Hamiltonian which describes how these moments interact.  As I will describe modern neutron scattering techniques allow a quantitative understanding of both of these, and therefore an understanding of the exotic ground state selection in these materials.  I will illustrate these with examples related to quantum spin ice, a disordered quantum spin liquid with an emergent quantum electrodynamics, and a non-collinear ordered state which is selected by an exotic "order-by-disorder" mechanism.

 

 

Niels Bohr Lecture by professor Steven H. Simon

  1. nov. 2019, kl. 15.15

Topologically Ordered Matter and Why You Should be Interested

Talk by: professor Steven H. Simon, Oxford University.

Abstract: In two dimensional topological phases of matter, processes depend on gross topology rather than detailed geometry. Thinking in 2+1 dimensions, particle world lines can be interpreted as knots or links, and the amplitude for certain processes becomes a topological invariant of that link. While sounding rather exotic, we believe that such phases of matter not only exist, but have actually been observed in quantum Hall experiments, and could provide a uniquely practical route to building a quantum computer.   Possibilities have also been proposed for creating similar physics in systems ranging from superfluid helium to strontium ruthenate to semiconductor-superconductor junctions to quantum wires to spin systems to graphene to cold atoms.

Niels Bohr Lecture by professor Charles H. Bennett

  1. nov. 2019, kl. 15.15

Raymond and Beverly Sackler Distinguished Lecture:

What Math and Physics can do help combat fake videos

Talk by: professor Charles H. Bennett, IBM Fellow at IBM Research

Abstract: The Progress in artificial intelligence has made it easy to produce “Deep Fake” videos that are so realistic that even experts have trouble identifying them, which then go on to spread virally, due to people’s susceptibility to content that entertains them and appeals to their prejudices or fears, especially when forwarded by friends with whom they correspond regularly.

It would seem that the hard sciences can do little to mitigate this problem, which has so much to do with psychology and human nature. But math and physics can be a significant part of the solution, by enabling anyone to validate where and when the video was made, and that it has not been subsequently altered. Unfortunately, these validation techniques are not widely known, and therefore not widely used.

I will show how anyone with a smartphone can generate extremely hard-to-fake videos whose authenticity can be verified without needing to trust either the maker of the video or any centralized authority.

Niels Bohr Lecture by professor Jens K. Nørskov

  1. okt. 2019, kl. 15.15

Catalysis for sustainable production of fuels and chemicals

Talk by: Jens K. Nørskov, Technical University of Denmark

Abstract: The development of a sustainable energy system puts renewed focus on catalytic processes for energy conversion. Electricity production from solar and wind is becoming economically competitive but we need to be able to store energy from these intermittent sources. Storage in the form of chemical bonds as fuels is very attractive, but converting electrical into chemical energy efficiently will require completely new catalytic materials. Insight into the way the catalysts work at the molecular level may prove essential to speed up the discovery process.

The lecture will outline a theory of heterogeneous catalysis that singles out the most important parameters determining catalytic activity and selectivity. I will use nitrogen reduction to ammonia as the main example and discuss the possibility to find sustainable alternatives to the well-known Haber-Bosch process.

Niels Bohr Lecture by JC Séamus Davis

  1. maj 2019, kl. 15.15

Visualizing Quantum Matter

Talk by: JC Séamus Davis Professor of Physics, University of Oxford, Oxford.

Abstract: Information technology including computing, communication, encryption and the internet are anticipated to become wholly quantum mechanical as part of the emerging second quantum revolution. Global IT corporations such as Google, Microsoft, IBM and Intel are investing intensively in a race to achieve dominance in the new field of quantum technology (QT). Three interrelated elements are critical to QT: quantum information, quantum devices, and the quantum materials from which they will be fabricated.

QT requires these new quantum materials to exhibit some combination of macroscopic quantum physics (e.g. superconductivity), quantum entanglement (nonlocal interdependence of multiple quantum devices), and quantum topology (topological preservation of macroscopic quantum functionality). New experimental techniques are required for design, discovery and analysis of such materials.

In this regard, direct visualization of electronic quantum matter at the atomic scale is a uniquely powerful technique. In this talk I will describe the development of new instruments and techniques for visualizing quantum matter. As examples, we will visually explore the previously unseen and very beautiful states including Kondo and Hund Metals, Electronic Liquid Crystals, Quantum Anomalous Hall States, and Electron-pair Crystals. Time permitting, I will discuss the implications of the general capability to visualize quantum matter, for fundamental physics research and also for advanced materials and new Technologies.

Niels Bohr Lecture by Marica Branchesi

  1. maj 2019, kl. 15.15

The new exploration of the Universe through gravitational-wave observations

Talk by: Marica Branchesi, assistant professor at the Gran Sasso Science Institute.

Abstract: Gravitational-wave experiments, in development for decades, have recently become mature observatories able to detect transient gravitational-wave signals from the cosmos. In rapid succession, they have produced a series of groundbreaking discoveries, starting on 14 September 2015 with the first detection of gravitational waves from the coalescence of a binary system of stellar-mass black holes by the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO).

Another epochal discovery happened on 17 August 2017, with the first observations of gravitational waves from the inspiral and merger of a binary neutron-star system by the Advanced LIGO and Virgo network, followed 1.7 seconds later by a weak short gamma-ray burst detected by the Fermi and INTEGRAL satellites. The most extensive observing campaign in human history led to the detection of multi-wavelength, electromagnetic signals associated with this event. This started a new era of “multi-messenger” exploration of the most energetic transients in the sky. 

The talk will give an overview of the recent gravitational-wave and multi-messenger observations, and their astrophysical implications with remarkable achievements in different astrophysical fields, from relativistic astrophysics to nucleosynthesis, nuclear physics and cosmology, and the prospects for the upcoming years.

Niels Bohr Lecture by prof. Paul Chaikin

  1. marts 2019, kl. 15.15

Quantifying hidden order out of equilibrium

Talk by: Paul Chaikin, Silver professor of physics at New York University

Abstract: While the equilibrium properties, states, and phase transitions of interacting systems are well described by statistical mechanics, the lack of suitable state parameters has hindered the understanding of non-equilibrium phenomena in divers settings, from glasses to driven systems to biology.

Here we introduce a simple idea enabling the quantification of organization in non-equilibrium and equilibrium systems, even when the form of order is unknown. The length of a losslessly compressed data file is a direct measure of its information content.

We use lossless data compression to study several out-of-equilibrium systems, and show that it both identifies ordering and reveals critical behavior and even some critical exponents in dynamical phase transitions. Our technique should provide a quantitative measure of organization in systems ranging from condensed matter systems in and out of equilibrium, to cosmology, biology and possibly economic and social systems.

Niels Bohr Lecture by prof. Francis Halzen

  1. jan. 2019, kl. 15.15

IceCube: Opening a New Window on the Universe from the South Pole

Talk by: Professor Francis Halzen, Wisconsin IceCube Particle Astrophysics Center and Department of Physics, University of Wisconsin–Madison

Abstract: The IceCube project has transformed a cubic kilometer of natural Antarctic ice into a neutrino detector. The instrument detects more than 100,000 neutrinos per year in the GeV to PeV energy range. Among those, we have isolated a flux of high-energy neutrinos of cosmic origin with an energy density similar to that of high energy photons and cosmic rays in the extreme universe. We recently identified their first source: on September 22, 2017, several astronomical telescopes pinpointed a flaring galaxy powered by an active supermassive black hole, as the source of a cosmic neutrino with an energy of 290 TeV. Archival IceCube data subsequently revealed in 2014 a flare of more than a dozen neutrinos from the same direction. At a distance of 4 billion lightyears, ten times further than the nearest such sources, the first cosmic ray accelerator seems to belong to a special class of active galaxies that may be responsible for the origin of the highest energy particles in the Universe.

 

 

Nobel lecture at by Gérard Mourou and Donna Strickland

  1. dec. 2018, kl. 15.00

One half of this year’s Nobel prize in physics was awarded to Profs. Donna Strickland and Gérard Mourou for their method of generating high-intensity, ultra-short optical pulses. In this last Niels Bohr Lecture of 2018 they will give back-to-back lectures about the work leading to their discovery.

Donna Theo Strickland is professor in physics at the University of Waterloo. She worked in the laser division of Lawrence Livermore National Laboratory from 1991 to 1992 and joined the technical staff of Princeton University's Advanced Technology Center for Photonics and Opto-electronic Materials in 1992. She joined the University of Waterloo in 1997. She served as fellow, vice president, and president of The Optical Society, and is currently chair of their Presidential Advisory Committee.

Niels Bohr Lecture by Prof. Henrik Rønnow

  1. nov. 2018, kl. 15.15

Quantum Magnetism – Neutrons in the Quasi-particle zoo

Henrik Rønnow is director of the Laboratory for Quantum Magnetism, part of the newly formed Institute of Physics (IPHYS) at the EPFL in Switzerland.

Abstract: The field of quantum magnetism forms an arena, where theoretical models and experiments on real materials meet to further our understanding of quantum many body physics. I will illustrate the unique role of neutron scattering through results on selected Cu2+ based materials serving as physical realizations of fundamental low-dimensional spin ½ models. Balancing the borderline between classical antiferromagnetic order and quantum fluctuating ground states, in some ways, theoretical description of fully quantum ground states as found in spin chains and ladders is currently more advanced than for ordered spin clusters, or even the simple 2D square lattice. The antiferromagnetically ordered unfrustrated 2D square lattice hosts behaviour not explainable by spin-wave theory. This observation from inelastic neutron scattering may provide the 'smoking gun' of so-called resonating valence bonds (RVB) that Anderson and co-workers propose to describe the enigmatic high-Tc cuprate superconductors.

Niels Bohr Lecture by professor Carsten Eden

  1. okt. 2018, kl. 15.15

A sea of waves, turbulence and mean flow

Professor Carsten Eden, Professor for Theoretical Oceanography at Universität Hamburg. 

Abstract: Below its wavy surface,  the ocean hosts a sea of wave motions usually invisible to the observer at the surface:  high-frequency sound waves caused by the compressibility of seawater,  low-frequency planetary waves caused by gradients in the background rotation of the flow, and internal gravity waves with intermediate frequencies caused by buoyant restoring forces and influenced by Earth's rotation.

In particular the latter two principal kinds of ocean waves are characterized by energy continuously populating a wide range of frequencies and wavenumbers. Such ocean wave energy spectra also tend to satisfy certain spectral laws which points  towards the importance of spectral energy transfers by non-linear interactions between the waves, acting akin to the energy transfers seen in small-scale turbulence. The dynamics and importance of such wave turbulence for the large-scale mean circulation and the energy cycle of the ocean and the climate system, and possible ways for parameterisations of the wave effects to be used in  coarse-resolution climate models will be discussed.

Niels Bohr Lecture by professor Klaus Mølmer

  1. sept. 2018, kl. 15.15

Schrödinger’s Ichtyosauria

Professor Klaus Mølmer, University of Aarhus, Denmark.

Abstract: From the early days of quantum mechanics, leading physicists were concerned about the role played by probabilities and the unphysical nature of the quantum jumps and the collapse of the state of quantum systems subject to measurement. Erwin Schrödinger tried to dismiss these problems by declaring that quantum theory applies exclusively to large ensembles of particles, governed by mean values and absent of randomness.  As late as 1952, Schrödinger thus claimed the very idea of experiments with single quantum particles to be “as absurd as the one of raising Ichtyosauria in the Zoo”.

A variety of single quantum systems are now routinely subject to experimental investigation in the laboratory. In the talk, I shall review methods used to control and describe the behavior of  these Ichtyosauria in the quantum laboratory. I shall also demonstrate the robustness of the Copenhagen interpretation of quantum mechanics while discussing recent extensions to our understanding of what is a quantum state. Finally, I shall show examples of how the random jump behavior of quantum systems may truly benefit their applications in crucial technologies such as quantum information processing and quantum metrology.

Niels Bohr Lecture by professor Ramamurti Shankar

  1. maj 2018, kl. 15.15

The royal road to Landau's Fermi liquid

Ramamurti Shankar is the John Randolph Huffman Professor of Physics and Applied Physics at Yale University.

Abstract: Decades ago Landau, using his unsurpassed intuition, invented a scheme for describing interacting non-relativisitc fermions, which goes by the name Landau's Fermi liquid. More recently this picture was rediscovered by applying the renormalization group of Kadanoff and Wilson to this problem, making it more accessible to mortals and readily amenable to generalizations, which is important now that Landau is no longer here to help us. 

In this talk I will provide the audience a gentle introduction to the fermion problem, the renormalization group as applied here,  and the natural emergence of the Fermi liquid as the solution. 

Niels Bohr Lecture by professor Jan Zaanen

  1. marts 2018, kl. 15.15

The string theory – condensed matter flirtation: an eyewitness account

Jan Zaanen is professor of theoretical physics at Leiden University, and well known for his seminal contributions to the theory of strongly interacting electron systems.

Abstract: A quake is rumbling through the core of physics: the empiricisms of condensed matter physics and the mathematics of string theory appear to have some deep relations. For the initiated this has an unusually strong allure, but since this cocktail involves some of the most impenetrable areas of physics it is not easy to communicate the excitement to the community at large. 

I will attempt to get some of it across by telling the story from the perspective of a  condensed matter theorist who learned string theory only quite recently. How string theory evolved from a reductionist’s enterprise into some modern incarnation of statistical physics, equipped with general relativity turbo’s and quantum information boosters in the form of the “AdS/CFT” holographic duality.

How the universality of general relativity turned into a classification method for phases of matter, including new forms of “quantum” matter characterized by dense quantum entanglements on the macroscopic scale. How the latter reveal highly unusual traits having eerie resemblances with the mysterious experimental observations, with as highlight the famous linear resistivity measured in the strange metal phase of the high Tc supercondcutors.

Niels Bohr Lecture by Ronald Hanson

  1. febr. 2018, kl. 15.15

Title: The dawn of quantum networks

Ronald Hanson, QuTech and Kavli Institute of Nanoscience, Delft University of Technology, The Netherlands.

Abstract: Entanglement – the property that particles can share a single quantum state - is arguably the most counterintuitive yet potentially most powerful element in quantum theory. The non-local features of quantum theory are highlighted by the conflict between entanglement and local causality discovered by John Bell. Decades of Bell inequality tests, culminating in a series of loophole-free tests in 2015, have confirmed the non-local of nature.

Future quantum networks may harness these unique features of entanglement in a range of exciting applications, such as quantum computation and simulation, secure communication, enhanced metrology for astronomy and time-keeping as well as fundamental investigations. To fulfill these promises, a strong worldwide effort is ongoing to gain precise control over the full quantum dynamics of multi-particle nodes and to wire them up using quantum-photonic channels.

Diamond spins associated with NV centers are promising building blocks for such a network as they combine a coherent electron-optical interface [1] (similar to that of trapped atomic qubits) with a local register of robust and well-controlled nuclear spin qubits [2].

Here I will introduce the field of quantum networks and discuss future plans and ongoing work with the specific target of realizing the first multi-node network wired by quantum entanglement, including first primitive network experiments [3,4].

 

 

Niels Bohr Lecture by professor Kip S. Thorne

  1. dec. 2017, kl. 16.15

A Nobel Prize talk December 14 at 16:15 in Aud. 1 at HCØ

Title: LIGO, and Gravitational Waves:  Adventures of a Theorist in a World of Experimenters

Kip S. Thorne received 1/4 Nobel Prize in Physics 2017 for decisive contributions to the LIGO detector and the observation of gravitational waves.

Abstract: Thorne will describe his personal experiences, and those of his theory students, in their 45 year effort to help experimental physicists create gravitational-wave astronomy.  He will also describe the quest to use gravitational waves to explore the warped side of the universe.

Niels Bohr Lecture by professor Nigel Goldenfeld

  1. okt. 2017, kl. 15.15

Title: The life and death of turbulence

Nigel Goldenfeld is Professor in Physics at the University of Illinoi, and the Director of the NASA Astrobiology Institute for Universal Biology at UIUC, and leads the Biocomplexity Group at the University's Institute for Genomic Biology.

Abstract: How do fluids become turbulent as their flow velocity is increased? During the last ten years, exquisite experiments, numerical simulations and pure theory have uncovered a remarkable series of connections between transitional turbulence, phase transitions and renormalization group theory, high energy hadron scattering, the statistics of extreme events, and even population biology. 

In this talk, I will outline how these developments and strange connections imply that a fluid at the boundary between turbulence and laminar flow behaves precisely like an ecosystem at the verge of extinction, a prediction that is supported by recent experiments.

Niels Bohr Lecture by professor Arthur B. McDonald

  1. sept. 2017, kl. 15.15

Title: The Science of the Sudbury Neutrino Observatory (SNO) and SNOLAB

Arthur B. McDonald, Queen’s University, Kingston, Canada

Abstract: A description of the science associated with the Sudbury Neutrino Observatory and its relation to other neutrino measurements will be given, along with a discussion of the new set of experiments that are at various stages of development or operation at SNOLAB.

These experiments will address perform measurements of neutrino properties and seek direct detection of Weakly-Interacting Massive Particles (WIMPS) as Dark Matter candidates. The experiments include SNO+, in which the central element of the SNO detector will be liquid scintillator with Te dissolved for neutrino-less double beta decay; DEAP, using about 3300 kg of liquid argon for single phase direct Dark Matter detection; SuperCDMS, a solid state bolometer system to start construction at SNOLAB in the near future; PICO, a direct Dark Matter experiment using bubble formation for detection and NEWS, a direct Dark Matter detector using high pressure gasses for low-mass WIMP detection.

Niels Bohr Lecture by professor Pablo Jarillo-Herrero

  1. april 2017, kl. 15.15

Title: Exploring Quantum Electronic Transport in Flatland

Abstract: Over the past decade, the physics of low dimensional electronic systems has been revolutionized by the discovery of materials with very unusual electronic properties where the behavior of the electrons is governed by the Dirac equation. Among these, graphene has taken center stage due to its ultrarelativistic-like electron dynamics and its potential applications in nanotechnology. Moreover, recent advances in the design and nanofabrication of heterostructures based on van der Waals materials have enabled a new generation of quantum electronic transport experiments in graphene.

In this talk I will describe our recent experiments exploring electron-electron interaction driven quantum phenomena in ultra-high quality graphene-based van der Waals heterostructures. In particular I will show two novel realizations of a symmetry-protected topological insulator state, specifically a quantum spin Hall state, characterized by an insulating bulk and conducting counterpropagating spin-polarized states at the system edges. Our experiments establish graphene-based heterostructures as highly tunable systems to study topological properties of condensed matter systems in the regime of strong e-e interactions and I will end my talk with an outlook of some of the exciting directions in the field.

Niels Bohr Lecture by Professor David Reitze

  1. marts 2017, kl. 15.15

Title: Last Tango in Space-Time: Detecting Gravitational Waves From Binary Black Hole Mergers for the First Time Ever Using LIGO

David Reitze has authored 250 publications, and is a Fellow of the American Physical Society and the Optical Society.

Abstract: The first direct detections of gravitational waves in late 2015 were made possible by a forty year experimental campaign to design, build, and operate LIGO, the Laser Interferometer Gravitational-wave Observatory.  

In this talk, I’ll cover gravitational waves and what makes them so difficult to detect and at the same time such powerful and unique probes of the universe. Most of the presentation will focus on the interferometers, the LIGO detections and their astrophysical implications.  

Time permitting, I’ll give a preview of where LIGO intends to go in the next decade and beyond.

Niels Bohr Lecture by Professor Michael E. Brown

  1. febr. 2017, kl. 15.15

The search for the Ninth Planet

Abstract: Recent evidence has show that the orbits of the most distant known objects in the solar system are unexpectedly perturbed.

Analytic calculations and computer models have shown that the only viable explanation for these perturbations is the presence of a massive planet on an eccentric orbit in the distant solar system.

I will discuss the observational and theoretical work that lead to this conclusion and discuss the ongoing worldwide efforts to find Planet Nine on the edge of the solar system.

Niels Bohr Lecture by professor Henk A. Dijkstra

  1. jan. 2017, kl. 15.15

Physics of El Niño

Abstract: The El Niño variability in the equatorial Tropical Pacific is characterized by sea surface temperature anomalies and associated changes in the atmospheric circulation. Through an enormous observational effort over the last decades, the relevant time scales and spatial patterns of El Niño are now well-documented. In the meantime, a hierarchy of models has been developed to understand the physics of this phenomenon and to make predictions of future events. In this presentation an overview will be given of (i) the robust and relevant details of the observations, (ii) the current state of the theory of the El Niño phenomenon and (iii) the forecast skill of models as evaluated after recent El Niño events.

 

 

Niels Bohr Lecture by Nobel Laureate 2016, Duncan Haldane

  1. dec. 2016, kl. 15.15

Physics Nobel Lecture 2016

Prize motivation: "for theoretical discoveries of topological phase transitions and topological phases of matter”.

Prof. Haldane got his PhD from Cambridge in 1978. He has since worked in Institut Laue-Langevin in Grenoble, University of Southern California in Los Angeles, AT&T Bell Labs in New Jersey, University of California San Diego and since 1990 he has been the Eugene Higgins Professor of Physics at Princeton university.

Citing from his homepage, “I am interested in strongly-interacting quantum many-body condensed-matter systems, explored by non-perturbative methods”. Currently this involves problems like the geometry of the fractional quantum Hall effect (FQHE), the entanglement spectrum of quantum states, model wavefunctions for the FQHE, and not least topological Insulators, and Chern Insulators.

Niels Bohr Lecture by Albert-László Barabási

  1. okt. 2016, kl. 15.15

Taming Complexity: Controlling Networks

Albert-László Barabási, Center of Complex Networks Research, Northeastern University and Division of Network Medicine, Harvard University.

Abstract: The ultimate proof of our understanding of biological or technological systems is reflected in our ability to control them. While control theory offers mathematical tools to steer engineered and natural systems towards a desired state, we lack a framework to control complex self-organized systems. Here we develop analytical tools to study the controllability of an arbitrary complex directed network, identifying the set of driver nodes whose time-dependent control can guide the system’s entire dynamics. We apply these tools to several real networks, finding that the number of driver nodes is determined mainly by the network’s degree distribution. We show that sparse inhomogeneous networks, which emerge in many real complex systems, are the most difficult to control, but dense and homogeneous networks can be controlled via a few driver nodes. Counter-intuitively, we find that in both model and real systems the driver nodes tend to avoid the hubs. 

Niels Bohr Lecture by Hans Jürgen Herrmann

  1. okt. 2016, kl. 15.15

Rotating Matter: The Bearing State

Niels Bohr Lecture by Hans Jürgen Herrmann. Rotating Matter: The Bearing State

Abstract: Granular materials are characterized by an additional degree of freedom, rotations, which become particularly relevant for spherical particles. They allow for soft modes under shear which do find realizations for instance in tectonic faults. A packing of spheres is called bi-chromatic if every loop formed by contacts is even.

In three dimensions, bi-chromatic bearings have many different sliding-free configurations, so called bearing states. If all loops have length four the system exhibits four continuous degrees of freedom and a systematic way of constructing  such bearing states can be devised.

The bearing state can be analytically predicted from the initial state without any information about the nature of the contact forces.  Any bearing state can be induced by controlling the angular velocities of only two spheres.  This allows for instance to amplify the angular velocity along a two parallel touching chains of equally sized spheres as a new way of gear design, that might find use in mechanics and robotics. When a single sphere is blocked a well-defined new bearing state is attained. It is also possible to determine the total mass and the center of mass  of the packing by analyzing its response to changes of the angular velocities of at most two spheres.

By considering spheres of different size, packings with bearing states can even be made space-filling. The construction and mechanical properties of such space-filling bearings will be discussed. Their bearing states can be viewed as a realization of solid turbulence exhibiting Kolmogorov scaling and anomalous heat conduction. In three dimensions a continuum of such configurations can be obtained as cuts through four-dimensional space-filling bearing states.

Niels Bohr Lecture by Alan Watson

  1. sept. 2016, kl. 15.15

The Highest Energy Particles in Nature

Niels Bohr Lecture by Alan Watson: The Highest Energy Particles in Nature

Abstract: About every 10 seconds, the earth’s atmosphere is hit by a cosmic ray of ~1020eV, the energy of a well-struck tennis ball. Where and how these extraordinarily-rare particles attain such energies is one of the mysteries of high-energy astrophysics. 

In an effort to solve these problems a detector covering 3000 km2, the Pierre Auger Observatory, has been built in Argentina to measure the properties of these particles with unprecedented precision, with a smaller one now operating in the United States. 

In my talk I will explain how we detect such rare cosmic rays and review some of the results.  Lack of knowledge of features of particle physics at energies beyond those attained at the LHC is a serious handicap to interpretation of the data but, despite this, some important astrophysical inferences can be drawn.  Plans for future detectors will be briefly mentioned.

Niels Bohr Lecture by Robert H. Austin

juni 2016, kl. 15.15

Collective Many-body Effects in Biology

Abstract: I have tried to get away from “one-body” fitness concepts in biology, and to take the next steps towards intrinsically many-body phenomena in biology. Although part of my work has involved testing quantum mechanics in sub-picosecond aspects of many-body effects in biology, I do think there are other coherent phenomena which are in some sense analogous to quantum mechanics in biology.

At the highest level, ecological system display collective many-body dynamics over vast ranges of space and time, which have wave-like properties. Some of the most fundamental questions in biology arise when we ask how such collective behavior is generated and regulated.

I’ll try to highlight recent advances in this broad area and to share ideas about how biology and physics can address these problems at a deep level.

Niels Bohr Lecture by Lisa Randall

  1. juni 2016, kl. 15.15

Dark Matter and the Dinosaurs

Abstract: I will explain dark matter and its influences. I will also discuss the Solar System and a possible connection between dark matter and periodic comet strikes.

Lisa Randall is a professor in theoretical particle physics and cosmology at Harvard University

Niels Bohr Lecture by Yoichi Ando

  1. april 2016, kl. 15.15

Topological Insulators and Superconductors

Abstract : Topological insulators and superconductors are new quantum states of matter that are characterized by nontrivial topological structures of the Hilbert space [1].

Recently, they attract a lot of attention because of the appearance of exotic quasiparticles such as spin-helical Dirac fermions or Majorana fermions on their surfaces, which hold promise for various novel applications [2].

In this talk, I will introduce the basics of those materials and present some of the key contributions we have made in this new frontier.

[1] Y. Ando, Topological Insulator Materials, J. Phys. Soc. Jpn. 81, 102001 (2013).

[2] Y. Ando and L. Fu, Topological Crystalline Insulators and Topological Superconductors: From Concepts to Materials, Annu. Rev. Condens. Mater Phys. 6, 361 (2015).

 

 

Niels Bohr Lecture by Prof. Michael Roukes

  1. nov. 2014, kl. 15.15

Integrated Neurophotonics:  A Vision for Massively-Parallel Interrogation of Brain Activity

Michael Roukes, a Robert M. Abbey Professor of Physics, Applied Physics, & Bioengineering California Institute of Technology

In 2011, six U.S. scientists from different disciplines banded together, outlined a vision [1], and managed to convince the Obama administration of the unprecedented opportunity that now exists to launch a coordinated, large-scale effort to map brain activity.  This culminated in the U.S. BRAIN Initiative (Brain Research through Advancing Innovative Neurotechnologies), which was launched in 2013.  Our vision was predicated on the current level of maturity of diverse fields of nanotechnology that, for the first time, can now be coalesced to realize powerful new tools for neuroscience.  I will outline the assertions we made, and focus upon our own collaborative efforts toward these goals – at Caltech and beyond – to realize this exciting potential.

Niels Bohr Lecture by Prof. Mark Raizen

  1. okt. 2014, kl. 15.15

Breaking Barriers with Maxwell's Demon

Prof. Mark G. Raizen, Center for Nonlinear Dynamics and Dept. of Physics,

Abstract: We are developing new approaches to the control of atomic motion. The starting point is the supersonic beam, an ultra-bright source of atoms. We use pulsed magnetic fields to stop the beam, and this approach is now proven to be optimum using an adiabatic slower. We further cool the atoms using a one-way wall, a direct realization of the historic thought experiment of Maxwell's Demon, proposed by James Clerk Maxwell in 1871.

This toolbox of new methods is an alternative to Laser Cooling, with much better predicted performance in terms of generality, flux of ultra-cold atoms, and phase-space density. We will use this ultra-bright source of atoms to pattern the nanoscale, bridging between atomic physics and condensed matter/material science.

I will conclude with some surprising ramifications of Maxwell's Demon which may even save your life.

Niels Bohr Lecture by Bert Schellekens

  1. sept. 2014, kl. 15.15

Particle Physics in the Multiverse

Bert Schellekens is a member of the theory group of the National Institute for Subatomic Physics (Nikhef) in Amsterdam

Abstract: Is our universe a single entity or part of a multiverse? Can the Standard Model of Particle Physics be derived uniquely from a fundamental theory, or is it just one of many possibilities? Insights from inflation and string theory in the past three decades suggests that it is not unique, and that the number of alternatives may be enormous.

This would have important implications for our attempts at understanding the Standard Model and the expectations for “new physics”.

It also implies that we cannot ignore an important bias in observations: the existence of observers. This leads inevitably to a controversial issue: the "anthropic principle”.

Inaugural lecture by Klaus Mosegaard

  1. juni 2014, kl. 15.15

Statistics in geophysical modeling: A good servant or a bad master?

Abstract: Ernest Rutherford, the British chemist who laid the groundwork for the development of nuclear physics, once said: "If your experiment needs statistics, you ought to have done a better experiment"! While there is some general thruth in this statement, there is no doubt that in geophysics our data are often so sparse, so insufficient, so inaccurate, and so inconsistent that some additional constraints (perhaps from statistics?) are needed to obtain a reasonable model of the Earth.

Our journey through the use (and abuse) of statistics begins around 1800 with the invention of "Least Squares", which has now become an accepted technique in, for example, linear regression, signal processing, and curve fitting. This method, which is build on assumptions of Gaussian statistics, also dominates geophysical modeling today. It is widely used to provide missing information in the many cases where data are insufficient to compute a unique solution. We shall investigate how the use of Least Squares influences current Earth models, often with poor results.

After these introductory observations we shall look at some recent work where Gaussian assumptions are replaced by more complex statistics, based on empirical data. This is done through an application of Bayes Rule where data is combined with "prior information" derived from observations of real Earth structure.

Niels Bohr Lecture by Jim White

  1. april 2014, kl. 15.15

Abrupt Climate Change: The View from the Past, Present and Future

Abstract: Climate is changing as humans put more and more greenhouse gases into the atmosphere. With CO2 levels around 400ppm today, we are committed to even more climate change, both in the near term, and well beyond our children’s future. A key question is how that change will occur. Abrupt climate changes are those that exceed our expectations, preparedness, and ability to adapt. Such changes challenge us economically, physically, and socially.

This talk will discuss abrupt change, as seen in the past in ice cores, as seen today, and what may be coming in the future.

 

 

Niels Bohr Lecture and NBIA Colloquium by Julia Collins

  1. dec. 2013, kl. 11.15

Abstract: I will tell the story of three best friends in 19th century Scotland and their attempt to develop an atomic theory based on knots and links. Tait, Kelvin and Maxwell were inspired by a fantastic experiment involving smoke rings, and their theories, whilst being completely wrong, inspired a new field of mathematical study which is once again becoming important in physics, chemistry and biology.

Niels Bohr Lecture by Dr. Peter Jenni

nov. 2013, kl. 16.00

The long journey to the Higgs boson and beyond at the LHC

Dr. Peter Jenni: After his retirement as a CERN Senior Research Staff end of April 2013, Peter Jenni has become a Guest Scientist with the Albert-Ludwigs-University Freiburg, Germany, keeping his full engagement with the ATLAS experiment.

Abstract: Since three years the experiments at the Large Hadron Collider (LHC) investigate particle physics at the highest collision energies ever achieved in a laboratory. Following a rich harvest of results for Standard Model (SM) physics came in 2012 the first spectacular discovery, by the ATLAS and CMS experiments observing a new, heavy particle which is most likely the long-awaited Higgs boson. The latest results with the full data sets accumulated over the first three-year running period of the LHC will be presented. Other, far-reaching results can be reported for exploratory new physics searches like Supersymmetry (SUSY) and its implication for Dark Matter in the Universe, Extra Dimensions, and the production of new heavy particles.

However, with this recent discovery of a heavy scalar boson the exciting journey into unexplored physics territory, within and beyond the SM, has only just begun at the LHC, in particular also in view of the increased collision energy expected for the next running period starting in 2015. Besides the first results and the future prospects, the talk will also touch on the history and the challenges of the whole LHC project, as well as on the fruitful collaboration of ATLAS with the NBI group since the very beginning of this large scientific adventure.

Niels Bohr Lecture by Prof. Achim Rosch

  1. okt. 2013, kl. 15.15

Dr. Achim Rosch, Institut fuer Theoretische Physik, Universitaet zu Koeln

Magnetic whirls in chiral magnets: skyrmions and monopoles

Abstract: In chiral magnets and small magnetic fields lattices of magnetic whirls, so-called skyrmions, can be stabilized. These skyrmions can be manipulated by electric currents which are 5-6 orders of magnitude smaller than conventionally needed for the manipulation of magnetic structures. The very efficient coupling of the magnetic structure to currents is governed by Berry phases, which can be described by effective "emergent" electromagnetic fields. The topological quantization of the the skyrmions thereby leads to a quantization of the emergent magnetic flux. A change of topology has to occur by singular magnetic configurations [3] which act as sources and sinks of the emergent magnetic flux. Thereby they can be viewed as emergent magnetic monopols.

Niels Bohr Lecture by Professor Priyamvada Natarajan

sept. 2013, kl. 15.15

Priya Natarajan is a Professor in the Departments of Astronomy and Physics at Yale University. She is a theoretical astrophysicist interested in cosmology, gravitational lensing and black hole physics.

Title: From seeds to behemoths: tracking the formation of supermassive black holes in the universe

Abstract: Populations of quasars powered by accretion onto SMBHs with masses in excess of 10^9 solar masses are now detected when the Universe was barely a Gyr old. And in the local universe the centers of several nearby brightest cluster galaxies harbor behemoths that weigh ~ a few times 10^10 solar masses.

I will discuss how these monster black holes likely form and what observational signatures can test the various formation & growth scenarios. Aside from outlining the current status of our understanding, I will close with the open exciting questions and challenges ahead for theory given the wealth of observational data in hand and in the pipeline.

Inaugural lecture by Anders Sørensen

  1. jan. 2013, kl. 15.15

Title: Quantum information processing with atoms and light

Abstract: The field of quantum information processing aims at exploiting the laws of quantum mechanics to process information in a way which is classically impossible. Because the fundamental logical structure of quantum mechanics is completely different from classical logic, there are certain computational tasks which can be solved more efficiently on a computer based on quantum mechanical principles than on the computers we are used to today. Famous examples include the factoring of large numbers, which if implemented on a quantum computer could break the security of most encryption protocols used on the internet today. From a physics perspective a more interesting possibility is that such a quantum computer would be an ideal tool for solving complicated quantum many body problems.

In the talk I will give an introduction to what quantum information processing is and the theories we have developed for how to implement it in practice. In particular I will talk about a new approach we are exploring, where we are trying to exploit decay and dissipation as a resource for quantum information processing.

Inaugural lecture by Arno Hiess

  1. marts 2013, kl. 15.15

Is It Love? The Interplay of Magnetism and Superconductivity as seen by Neutrons

Neutron scattering is of particular importance to appreciate the interrelation of magnetism and superconductivity. They help answering the following essential questions: Are magnetism and superconductivity two different phenomena or manifestation of a new ground state? How can neutron spectroscopy reveal the symmetry of the corresponding order parameters? What are the energy scales relevant for the superconducting coupling mechanism?

During my lecture I will first present results from neutron diffraction experiments used to investigate static microscopic properties. They reveal details of the moment arrangement but also the spin and orbital contributions of the (paramagnetic) magnetic moment.

The spin dynamics in momentum and energy space can be studied by neutron spectroscopy. Upon entering the superconducting state the energy dependence of the dynamic response changes at selected momentum space positions, reflecting the opening of the superconducting gap.  I will present various examples from different classes of unconventional superconductors with an emphasis on cerium- and actinide-based intermetallic superconductors.

Those experiments profited from the latest neutron instrumentation at both ILL, Grenoble, France and FRM2, Munich, Germany and pave the way to future investigations. In the last part of my presentation I will present some challenges and discuss how those will be addressed with the instrumentation at the next generation neutron source ESS in Lund, Sweden.

Inaugural lecture by Pascale Deen

Uncovering magnetic correlations using neutrons and x-rays as probes

  1. marts 2013, kl. 15.15

Abstract: Huge technological advances have been possible by better understanding and thus manipulating electronic properties of materials.  Many advances have been made yet the behaviour of correlated spin structures, as found in emergent complex phenomena, cannot be predicted even though the interaction of individual electrons and lattices are fairly well understood. Collective behaviour drives these emergent phenomena and as such it is imperative to probe and perturb materials that display strong electron correlations. 

X-rays and neutrons are ideal probes to investigate the microscopic electronic correlations of solids.  The strength of scattering techniques lies in the ability to measure simultaneously spatial and time correlations, thus providing information on the different length and energy scales responsible for electronic phenomena. Such direct microscopic information makes neutron and x-ray scattering ideal to benchmark experimental results against theoretical models. 

I shall give an overview of some of the unusual magnetic phenomena that I have had the pleasure to work. These scientific endeavours will be linked to the perspectives for neutron instrumentation at the ESS and collaborative x-ray scattering instrumentation needs.

Niels Bohr Lecture by Prof. Victor Yakovenko

  1. maj 2013, kl. 15.15

Prof. Victor Yakovenko, University of Maryland

Statistical Mechanics of Money, Income, Debt, and Energy Consumption

Abstract: By analogy with the probability distribution of energy in statistical physics, I argue that the probability distribution of money in a closed economic system should follow the exponential Boltzmann-Gibbs law.  Analysis of the empirical data shows that income distribution in the USA has a well-defined two-class structure.  The majority of the population (about 97%) belongs to the lower class characterized by the exponential ("thermal") distribution.  The upper class (about 3% of the population) is characterized by the Pareto power-law ("superthermal") distribution, and its share of the total income expands and contracts dramatically during bubbles and busts in financial markets.  The probability distribution of energy consumption per capita around the world also follows the exponential Boltzmann-Gibbs law, which is consistent with entropy maximization.  For more information, see http://physics.umd.edu/~yakovenk/econophysics/, Reviews of Modern Physics 81, 1703 (2009), New Journal of Physics 12, 075032 (2010).  This work is currently supported by the Institute for New Economic Thinking.

Niels Bohr Lecture by Prof. Jeff Kimble

  1. juni 2013, kl. 15.15

Title: Quantum Networks

Wednesday, June 12, 2013 at 15:15 in Aud. 3 at HCØ.

Abstract:
Quantum networks offer opportunities for the exploration of physical
systems that have not heretofore existed in the natural world with
applications to quantum computation, communication, metrology, and quantum
many-body physics. To create a quantum network, quantum states are
generated and stored locally in quantum nodes. These nodes interact over
quantum channels to enable entanglement to be spread across the network.

In my lecture, I will provide an overview of quantum networks from formal
to physical. I will discuss research for the laboratory realization of
small networks composed of atoms that interact strongly by way of single
photons. The goal is to achieve lithographic quantum optical circuits, for
which atoms are trapped near nano-scopic dielectric structures and wired
together by photons propagating through optical waveguides. Single atoms
can endow quantum functionality for otherwise linear optical circuits and
thereby provide the capability to build quantum networks component by
component.

Niels Bohr Lecture by Prof. Subir Sarkar

  1. sept. 2013, kl. 15.15

Prof. Subir Sarkar, University of Oxford and NBI

Title: Connecting inner space & outer space

Wednesday, September 4, 2013 at 15:15 in Aud. 3 at HCØ.

Abstract: We have just celebrated the centenary of the finding that the Earth is being constantly bombarded by high energy `cosmic rays' from space. This initiated a glorious era of discovery of many new particles (positron, muon, pion, ...) and developed into accelerator-based research into high energy physics. A century later this has given us the triumphant `Standard Model' of particle physics which provides a precise quantum description of all fundamental processes in terrestrial laboratories, including (with the recent discovery of "a Higgs boson") an understanding of how particles acquire mass.

Unfortunately the Standard Model does not explain any of the salient features of the universe as a whole - Why there is matter but no antimatter? Why there is so much more `dark matter' of unknown origin? Why is the expansion rate apparently accelerating, as if driven by a Cosmological Constant-like, dominant component of `dark energy'?

In this lecture I will describe how new kinds of experiments and theoretical developments at the rapidly growing interface of astro-particle physics are attempting to answer these cosmic questions, by linking them to possible new physics that lies beyond the Standard Model.

 

 

Niels Bohr Lecture by Jörg Wrachtrup

  1. nov. 2012, kl. 15.15

From atomic memory to nanoscale precision measurements

Joerg Wrachtrup, University of Stuttgart, Germany

Precision measurements have been a key driving source for the development of quantum technologies. The improvements for atom clocks as an example have inspired novel cooling methods and finally lead to ion-based quantum information processing. Solids so far had little share in these developments mostly because the generation of quantum devices in solid state materials is hampered by thorough interaction of qubits with their environment.

Over the past couple of years, however, solid state quantum devices have matured and nowadays a whole set of system with “atom-like” properties are known. Among them, diamond defects are outstanding due to their inherent protection from environmental fluctuations which make them well controllable quantum systems even at room temperature. Spin impurities in diamond promise to be efficient quantum memories for microwave but also optical photons.

Nanotechnology has advances to such a degree that strongly coupled spin arrays can be fabricated which are of use in quantum information processing and quantum simulations and might prove to be key elements in quantum repeater schemes. In addition, diamond defects can be positioned into nanostructured diamond material. As such they are used as nanoprobes for e.g. electric and magnetic fields. Quantum enhancement of sensitivity of such probes comes from precision measurement techniques formerly used in quantum and atom optics.  

Niels Bohr Lecture: Nobel Colloquium 2012

  1. dec. 2012, kl. 17.30

The Nobel Prize in Physics 2012 was awarded jointly to Serge Haroche and David J. Wineland "for ground-breaking experimental methods that enable measuring and manipulation of individual quantum systems".

Niels Bohr Lecture by David B. Sanders

The Infrared Universe: The Cosmic Evolution of Superstarbursts and Merging Massive Black Holes

  1. sept. 2012, kl. 15.15

David B. Sanders, Institute for Astronomy, University of Hawaii.

Our current view of galaxy evolution has been dramatically enhanced by new deep field surveys at far-infrared and sub-millimeter wavelengths.  Evidence now suggests that the extragalactic luminosity density in the far-IR/submm region of the electromagnetic spectrum exceeds that in the optical/ultraviolet by factors of 2-5 at redshifts z > 1, implying that as much as 80% of the "activity" in galaxies in the distant Universe is hidden by dust.  Much of this obscured activity occurs in Luminous Infrared Galaxies (LIRGs), which appear to be triggered by major mergers of gas-rich spirals.  

LIRGs are powered by both dust-enshrouded super-starbursts and accretion onto massive black holes (MBH). The LIRG phase ends shortly after the merger of the two MBH, which triggers an ejection of most of the surrounding gas and dust, leaving behind a gas-poor, massive elliptical galaxy. 

This major event in galaxy evolution has been largely missed by deep UV/optical surveys.  Our own galaxy, the Milky Way will likely suffer a similar fate 5 billion years hence, when it merges with our large neighbor - the Andromeda galaxy.  The merger of two MBH (~10^6 Msun), will be one of the prime targets for testing General Relativity using the Laser Interferometer Space Antenna.  Our results for the number density of LIRGs suggest that such events may be as common as one per month.

Inaugural lecture by Ken Andersen

Half a career in neutron scattering

  1. maj 2012, kl. 13.15

Ken Andersen, head of the Instruments Division at the ESS in Lund, Sweden.

Neutron scattering can give both qualitative and quantitative information about the structure and dynamics of materials which is inaccessible using any other technique. The amount of information which can be extracted is, however, often severely restricted by the inherently low brightness of even the most intense neutron sources in the world. Over the last 30 years or so, almost all of the improvements in neutron data quality have been driven, not by increases in source brightness, but by improvements in neutron scattering instrumentation.

I will give an overview of the neutron instrumentation work which I have been involved with, ranging from backscattering spectroscopy to polarisation analysis and general time-of-flight instrument design. Some perspectives are given for instruments at the ESS.

Niels Bohr Lecture by Peter Hirschfeld

Led by the nodes: forging an understanding of Fe-based superconductors

  1. maj 2012, kl. 13.15

The origin of superconductivity in most new materials discovered in the past two decades remains a mystery, and represents one of the main unsolved questions of condensed matter physics.

Peter Hirschfeld, University of Florida

The new Fe-based superconductors have occasioned considerable excitement because transition temperatures are high, and it is hoped that the existence of a second class of such superconductors, in addition to cuprates, will lead to new insights into the essential ingredients for high temperature superconductivity.

I will review what is known about the superconducting state and explain the basis for the near-consensus that almost all pnictide materials display spin singlet, s-wave symmetry. Different experimental probes on different materials show a large diversity of superconducting gap structures, with evidence for both gap nodes and fully gapped behavior. Within the context of a spin fluctuation pairing theory of such systems, this variety of gap structures, unexpectedly based on intuition from the high-Tc cuprates, is easy to understand.

High-Tc superconductivity in these unusual multiband materials poses anew, and offers new insight into, the question of how higher temperature superconductivity might be achieved.

Niels Bohr Lecture by Christoph Rembser

The physics programme at the PS and SPS: CERN's unique scientific breadth

  1. april 2012, kl. 13.15

While the main focus over the past years has shifted towards flagship experiments at colliders, a rich and exciting physics programme is carried out at the CERN Proton-Synchrotron (PS) and Super-Proton-Synchrotron (SPS), attracting large scientific communities from the various fields of physics.

In my talk I will introduce the CERN PS and SPS accelerators which are successfully and efficiently operating since many years and which are providing a wide range of different particle beams. This beams with energies up to 450GeV are used in various experimental facilities like the Antiproton Decelerator, the Neutron Time-of-Flight facility, the PS and SPS experimental areas and at the CNGS beamline which provides a beam of high-energy neutrinos to the Gran Sasso laboratory about 730km away from CERN.

I will present an overview on the physics programme of CERNs "lower energy" accelerators and will report on its experiments. As the PS and SPS also serve as injectors for the Large Hadron Collider LHC, I will review their operation modes and possible injector upgrades which will ensure to keep CERN's unique scientific breadth and that the experiments at the PS and SPS will remain an important and indispensable part of the laboratories activities.

Inspirationsforedrag med Rikke Sønder Larsen

Der ligger et stort potentiale for danske uddannelsesinstitutioner, i forhold til danske og internationale virksomheder ved at tænke i alternative samarbejdsformer. Det er en kilde til finansiering af ny forskning og en mulighed for at komme tættere på "behovene" hos virksomhederne.

  1. april 2012, kl. 13.15

Uddannelsesområdet spiller en central rolle i forhold til de private virksomheder ved at levere arbejdskraft, nye fokusområder, forskning, og som kulturbærende- og opdragende institutioner. Samtidig arbejder danske virksomheder i stigende grad med "forretningsdrevet CSR - Corporate Social Responsibility". Det betyder, at virksomhederne har fået øjnene op for, at der kan være store fordele i at tænke deres sociale ansvar sammen med bundlinje. Og her er uddannelse et centralt konkurrenceparameter for videnbaserede virksomheder.

Inaugural lecture by professor Alexander Baklanov

PHYSICAL AND CHEMICAL WEATHER: A NEW CONCEPT AND METHODOLOGY OF

  1. marts 2012, kl. 13.15

INTEGRATED MODELLING

Professor Alexander Baklanov, CEEH deputy director

During the last decade a new field of atmospheric modelling - the chemical weather forecasting (CWF) - is quickly developing and growing. However, in most of the current studies and publications this field is realised in a simplified concept of the off-line running chemical transport models with operational numerical weather prediction (NWP) data as a driver. A new concept and methodology considering the chemical weather as two-way interacting nonlinear meteorological and chemical/aerosol dynamics processes of the atmosphere is suggested and discussed. The on-line integration of mesometeorological models and atmospheric aerosol and chemical transport models gives a possibility to utilize all meteorological 3D fields in the chemical transport model at each time step and to consider nonlinear feedbacks of air pollution (e.g. atmospheric aerosols) on meteorological processes / climate forcing and then on the chemical composition. This very promising way for future atmospheric simulation systems (as a part of and a step to Earth System Modelling) will lead to a new generation of models for meteorological, environmental and chemical weather forecasting. The methodology how to realise the suggested integrated CWF concept is demonstrated on example of the European Enviro-HIRLAM integrated modelling system. Importance of atmospheric boundary layer and different feedback mechanisms for meteorological and atmospheric chemistry processes and their strong nonlinearities are also discussed in the lecture.

 

 

Niels Bohr Lecture by Saul Perlmutter

Nobel Prize winner, Professor Saul Perlmutter, will visit DARK on Thursday, December 15, to meet with researchers and give the Niels Bohr Lecture, at 13.15 that day in Auditorium 3 at the H.C. Ørsted Institute, Universitetsparken 5, 2100 Copenhagen.

  1. dec. 2011, kl. 13.15

This year Perlmutter, along with Brian P. Schmidt and Adam G. Riess, was awarded the Nobel Prize for Physics for the discovery of the accelerating expansion of the Universe through observations of distant supernovae.

Professor Permultter leads the Supernova Project, and many other projects, at the University of California at Berkeley.

Inaugural lecture by Peter Lodahl

  1. nov. 2011, kl. 13.15

Quantum optics studies the fundamental interaction between photons and matter and is usually considered a research discipline where extremely pure optical systems are investigated. For example, a paradigm in quantum optics is a single two-level atom considered to be alone in the universe and allowed to interact only with a single photon.

Niels Bohr Lecture by Raymond Pierrehumbert

  1. sept. 2011, kl. 13.15

Title: New Worlds, New Climates

Abstract: The past decade has witnessed the birth of what amounts to a new field of science: comparative planetology based on characteristics of newly discovered extrasolar planets. The pace of discovery has accelerated, with the release of over a thousand new planet candidates from the first year of the Kepler mission alone. 

These new worlds provide an opportunity to revisit some classic problems in planetary climate, but also pose questions about the nature of planetary climate that climate physicists have never before had cause to think about. 

After providing an overview of the characteristics of the exoplanets discovered so far, I will discuss several examples of these new climate problems. These include: Climates of tide-locked worlds; Climates of planets orbiting faint red stars; Exotic spin states; Generalization of the silicate weathering thermostat; Habitability of "mini-Jupiters" beyond the conventional habitable zone.

Niels Bohr Lecture by Soucheng Zhang

sept. 2011, kl. 13.15

Title: Topological insulators and topological superconductors

Soucheng Zhang, Professor of Physics

Abstract: Recently, a new class of topological states has been theoretically
predicted and experimentally observed. The topological insulators have an insulating gap in the bulk, but have topologically protected edge or surface states due to the time reversal symmetry. Similarly, topological superconductors or superfluids have novel edge or surface states consisting of Majorana fermions. In this talk, I shall review the recent theoretical and experimental progress in the field, and focus on a number of outstanding issues, including the quantized anomalous Hall effect, quantized magneto-electric effect, the topological Mott insulators and the search for topological superconductors.

Niels Bohr Lecture by Jamie Nagle

15. juni 2011, kl. 13.15

Jamie Nagle is a Professor of Physics at the University of Colorado at Boulder, where he is researching in the field of experimental high-energy heavy ion physics.  

Title: Mysteries of Deconfined Quark-Gluon Matter

Abstract: Despite the realization over 40 years ago that protons and neutrons are not fundamental particles and instead composed of quarks and gluons, a concrete understanding of the properties of quark-gluon matter have remained elusive. Quarks and gluons freed from confinement in protons and neutrons (or other hadrons) is predicted to be present under extreme conditions in the core of neutron stars and formerly in the earliest stages of our universe. Over the last ten years, studies of such high temperature matter have been carried out at the Relativistic Heavy Ion Collider and just this last year at even higher temperatures at the Large Hadron Collider.

The talk will explore new experimental data combined with theoretical modelling that is revealing the truly unique properties of this quark-gluon matter.

Niels Bohr Lecture by Jeffrey Hangst

13. april 2011, kl. 13.15

Jeffrey Hangst, Institut for Fysik og Astronomi, Aarhus Universitet og CERN.

Antihydrogen - Stable, Neutral Antimatter

What would you do if you could get your hands on some neutral, stable antimatter? No matter what you may have seen in the cinema, blowing up the Vatican is not an option - trust me on this.

In 2010, the ALPHA experiment at CERN demonstrated [1] that it is indeed possible to capture and hold atoms of antihydrogen - element number -1 on the periodic table. We have been producing antihydrogen in quantity at CERN since 2002, when the ATHENA experiment showed how to synthesize it from cold clouds of antiprotons and positrons [2].

In this lecture I will discuss how to make antihydrogen, and then I will describe the many additional steps necessary to be able to trap and hold it. With antihydrogen held for questioning, we can now address what has long been one of the most intriguing remaining questions about nature: Do atoms of matter and antimatter obey the same laws of physics? I will describe how we in ALPHA plan to tackle this question.

  1. Andresen, G.B. et al., Trapped Antihydrogen, Nature 468, 673 (2010).
    2. Amoretti, M. et al., Production and detection of cold antihydrogen atoms. Nature 419, 456 (2002).

Jeffrey S. Hangst, Aarhus University, Spokesperson. The ALPHA Collaboration

Niels Bohr Lecture by Martin Plenio

  1. marts 2011, kl. 13.15

Professor Martin Plenio, Institute of Theoretical Physics, Ulm University

Title: Quantum mechanics and noise in biology

Speaker: Martin Plenio, Universität Ulm

Abstract: Recently, thanks to the convergence of quantum optical technology and biophysics, we have gained the ability to explore theoretical questions concerning the interplay of quantum coherence and noise in complex quantum systems in actual experiments.

This development opens up new avenues of scientific enquiry and is bringing together researchers from physical chemistry, biology and quantum information in a quest for a deeper understanding of the role of quantum physics for the foundation of biology.

Fratrædelsesforelæsning af Professor Jørn Dines Hansen

  1. marts 2011, kl. 13.15

Fratrædelsesforelæsning af Professor Jørn Dines Hansen, Niels Bohr Institutet

50 år med HEP
Jeg vil i mit foredrag beskrive udviklingen i partikelfysik eller højenergifysik, HEP, i de sidste ca. 50 år og nogle af mine bidrag til eksperimenterne og analysen af dem fra boblekamre til det store elektronik eksperiment ATLAS på CERN.

Niels Bohr Lecture by Roger Penrose

  1. febr. 2011, kl. 13.15

TITLE: Can we see through the Big Bang, into another World?

Abstract:
The proposal of Conformal Cyclic Cosmology (abbreviated CCC) asserts that what we presently regard as the entire history of our universe, from its Big-Bang origin to its indefinitely expanding future, is but one aeon in an unending succession of similar such aeons, where the infinite future of each matches to the big bang of the next via an infinite change of scale. CCC predicts that supermassive black-hole encounters in the aeon prior to ours would be observable to us as families of concentric rings of unusual temperature structure in the cosmic microwave background. Recent analysis of data from the WMAP satellite has been argued to provide possible confirmation of this signal, allowing us to "see through" our Big Bang to such events occurring in the aeon prior to ours. The status of this controversial proposal will be discussed.

Niels Bohr Lecture by Ignacio Cirac

  1. jan. 2011, kl. 13.15

Professor Ignacio Cirac, Max-Planck Institut für Quantenoptik