Physics Friday Colloquia

Department of Physics

Physics Friday Colloquia

– Spring 2020

 

7 February 2020 - The Impacts of Energetic Particle Precipitation into the Atmosphere

Place: R10

Time: 14:15

Title: The Impacts of Energetic Particle Precipitation into the Atmosphere

Speaker: Yvan Orsolini

Abstract: The sun influences the climate of the earth not only through its radiative forcing but also -at least potentially- through energetic particle precipitation (EPP).  EPP refers to the precipitation into the upper atmosphere of protons originating from the sun during relatively rare and sporadic solar proton events, or else of electrons originating from the earth radiation belts. The latter give rise to phenomenon of aurora borealis. During geomagnetic storms, the electrons can be more energetic and penetrate into the mesosphere, the atmospheric layer between 50 and 90 km.
 EPP generates nitrogen and hydrogen oxides through a complex chemistry involving neutral and ionic trace species. While the broad aspects of the EPP impact on middle atmosphere chemistry is captured by state-of-the-art models and largely supported by satellite observations, its potential feedback on the general atmospheric circulation -hence on climate- is still debated.  We present the basic modelling tools currently used to address this challenging question at the interface of dynamic meteorology and space sciences. 

 

14 February 2020 - Fluid Mechanics

Place: R10

Time: 14:15

Title: Fluid Mechanics

Speaker: Simen Ådnøy Ellingsen

Abstract: When a depth-varying current is present beneath the water surface it can affect surface waves profoundly. The interaction of water waves and sub-surface shear currents has been studied for 7 decades, yet their importance to a wide array of applications has only been widely recognised in relatively recent times. Waves and shear currents co-exist, e.g., in river deltas with strong surface jets, surface shear layers in the wind-swept ocean, and flow over shallows where the bottom boundary layer becomes important to wave motion.
The talk has two parts: the first concerns how shear affects waves, to wit ring waves and ship waves, the second takes the inverse view of inferring the sub-surface current from measurements of surface waves. 
Lord Kelvin famously showed in 1887 that waves behind a ship in deep water always forms the same angle, approximately 39 degrees. We showed theoretically, that in the presence of vertical shear this no longer holds, and different angles, and even asymmetric ship waves can result. Likewise,  ring waves from a localised disturbance can become strikingly asymmetric. In a recent experiment these effects were observed for the first time. Applying the theory to realistic ships on a real, measured current shows that ship fuel consumption can be drastically mispredicted if the depth-structure of the current is not correctly accounted for. 
A method is then presented for remote-sensing of surface currents by observing ambient water waves from above. Significant improvement over state-of-the-art methods is demonstrated for strongly sheared profiles. The method is ideal for current measurements using radar or optical video, from ships, drones or in the future even satellites, and unlike in-situ single-point measurements can cover large areas quickly. 
A brief overview of opportunities for advanced fluid mechanics courses and Masters thesis projects in the Thermo-Fluids group at the Dept of Energy & Process Engineering NTNU will be given.

 

21 February 2020 - Flight of synthetic whirling fruits

Place: R10

Time: 14:15

Title: Flight of synthetic whirling fruits

Speaker: Andreas Carlson

Abstract: Wind dispersion of seeds is a widespread evolutionary adaptation found in plants, which allows them to multiply in numbers and to colonize new geographical areas. Appendages of seeds, fruits and other diaspores (dispersal units) are essential for their wind dispersal, as they act as wings and enable them to fly. Whirling fruits generate an auto-gyrating motion from their sepals, a leaf like structure, which curve upwards and outwards, creating a lift force that counteracts gravitational force. In this talk, I will present how we have combined a simple theoretical model and experiments to understand how the shape of the wings of whirling fruits may have evolved into a form optimal for its wind dispersion potential, i.e., a maximal flight time/minimal terminal descent velocity. Similar shapes are found for a wide range of whirling fruits collected in the wild, highlighting that wing curvature (fold angle) can aid wind dispersal of whirling fruits and may improve the fitness of their producers in the context of an ecological strategy.

 

28 February 2020 - Nano comes to life

Place: R10

Time: 14:15

Title: Nano comes to life

Speaker: Sonia Contera

Abstract: Drawing on her perspective as one of today’s leading researchers in the field, Contera describes the exciting ways in which nanotechnology makes it possible to understand, interact with, and manipulate biology—such as by designing and building artificial structures and even machines at the nanoscale using DNA, proteins, and other biological molecules as materials. In turn, nanotechnology is revolutionizing medicine in ways that will have profound effects on our health and longevity, from nanoscale machines that can target individual cancer cells and deliver drugs more effectively, to nanoantibiotics that can fight resistant bacteria, to the engineering of tissues and organs for research, drug discovery, and transplantation.
The future will bring about the continued fusion of nanotechnology with biology, physics, medicine, and cutting-edge fields like robotics and artificial intelligence, ushering us into a new “transmaterial era.” As we contemplate the power, advantages, and risks of accessing and manipulating our own biology, Contera offers insight and hope that we may all share in the benefits of this revolutionary research.

 

6 March 2020 - Molecular Beam Epitaxy at the QuSpin MBE lab

Place: R10

Time: 14:15

Title: Molecular Beam Epitaxy at the QuSpin MBE lab

Speaker: Christoph Brune

Abstract: The MBE lab is a new addition to the lab activities at IFY and we are still in the build-up process. In this talk I will give an overview on molecular beam epitaxy and the current status of our new lab. I will also briefly present our research plans for the near future.

 

13 March 2020 - Disciplining effects of physics jokes - CANCELLED 

Place: R10

Time: 14:15

Title: Disciplining effects of physics jokes

Speaker: Maria Berge

Abstract: 

Q: Who was the first electric detective?
A: Sherlock Ohms

Get it? This joke’s humour relies on the hearer’s previous knowledge of two usually unrelated facts: that Sherlock Holmes is a fictional detective and that Ohm’s law describes a fundamental relationship between electric current and potential difference. Did you laugh? The primary function of a joke is to make people laugh, but another function can be to create or support intimacy through acknowledging the shared knowledge of an in-group. Physicists have a certain kind of humour and humour has many positive effects: it brings people together and is useful when we interact with each other as tension release. However, we must also carefully consider why we find jokes funny. In this presentation are I will give you several examples of physics jokes but also how humour and jokes may have disciplining effects on an audience.
 

 

20 March 2020 - Quantum heat engines - CANCELLED

Place: R10

Time: 14:15

Title: Quantum heat engines

Speaker: Rosario Fazio

Abstract: Small quantum systems connected to several different thermal reservoirs probably constitute the smallest heat engines one can imagine. Their operating mode may be quite different from their macroscopic counterpart, intimately linked to the dynamics of quantum open systems. Fluctuations and quantum effects, for example, are essential in the characterisation of the performance of the thermal machines. I will try to give an overview of the field with an emphasis on some fundamental questions that can be addressed through the study of quantum heat engines. I will further provide some examples where collective phenomena or adiabatic dynamics play a deisive role. 

 

27 March 2020 - Motivation for physics - CANCELLED

Place: R10

Time: 14:15

Title: Motivation for physics 

Speaker: Maria Vetleseter Bøe

Abstract: Why do our students choose physics? How does their motivation to learn physics interact with our teaching? The talk discusses these questions in light of international and national research, and presents preliminary results from the IMPEL project, which studies motivation among physics students at five Norwegian universities, including NTNU. 

 

3 April 2020 - Cosmological viscosity - CANCELLED

Place: R10

Time: 14:15

Title: Iver Håkon Brevik

Speaker: 

Abstract: I intend first to deal with the fundamental aspects of general relativity (GR), then move on to the Einstein equations in which the viscosity coefficients are plugged in “by hand” in the energy-momentum tensor.  Some comparison with observations is given. Perhaps surprisingly, the shear and bulk viscosity coefficients  so  well  known from ordinary fluid mechanics   can be incorporated also in GR  in a natural way.  Especially, this holds for the bulk viscosity. In the analogous more modern theories of QCD matter, the viscosity coefficients  similarly turn up. The viscosity concept is ubiquitous. 
The talk will be relatively simple, mathematically.  It should be easy to follow for physics students in their 3rd or fourth year.

 

17 April 2020 - Student project presentations - CANCELLED

Place: R10

Time: 14:15

Title: Student project presentations

Speaker: Students

Abstract:

 

24 April 2020 - Superconductivity - the universe in a droplet of Mercury - CANCELLED

Place: R10

Time: 14:15

Title: Superconductivity - the universe in a droplet of Mercury

Speaker: Asle Sudbø

Abstract: Superconductivity, first discovered upon cooling droplets of Mercury, is the astonishing phenomenon that a metal looses all of its electrical resistance at a sharply defined temperature when it is cooled down. Perhaps even more remarkably, the metal drastically changes its electromagnetic properties at the same sharply defined temperature, in that the metal completely expuls a magnetic field in the superconducting state. Both the loss of electrical resistance and the expulsion of magnetic field are results of a phase-transition taking place among the electrons of the system. I will explain what this phase- transition is, and how it leads to the loss of resistance. The most profound aspect of the phenomenon, the expulsion of magnetic field, has a close analog in phase-transitions in the early universe predicted by the Standard Model.  I will explain this analog, and will also explain how the search for the Higgs-particle at the Large Hadron Collider at CERN has a table-top analog in superconductors.

 


Physics Colloquia Spring 2020

 

The Physics Colloquia at the Department of Physics are open to all. An important goal for the colloquia is to be a meeting place between faculty and students to learn about interesting developments in physics. Students are especially encouraged to attend. Speakers are asked to keep the talks at a level targeting a master student in physics but even bachelor students should be able to appreciate the content of the talks.

The presentations start at 14.15 but everyone is encourage to arrive at 14.00 for some coffee, pastries and mingeling with faculty and students.

In the spring semester 2020 all colloquia are in Realfagbygget R10.

If you have any suggestions for colloquia speakers, contact the coordinator.

 

September

4/9 Current Challenges for Quantum Computing

David DiVincenzo, RWTH Aachen  [Webinar]

18/9 Multi-messenger searches for the sources of ultra-high energy cosmic rays and high-energy neutrinos

Foteini Oikonomou, NTNU  [Seminar]

25/9 Biomedical applications of HOT plasmonic nanoparticles

Lene B. Oddershede, Niels Bohr Institute, Denmar  [Seminar]

 

October

2/10 What is new under the Sun?

Mats Carlsson, University of Oslo, Norway  [Seminar]

12/10 Writing Science

Joshua Schimel, UC Santa Barbara, USA  [Webinar]

16/10 Disciplining effects of physics jokes

Maria Berge, Umeå University, Sweden  [Seminar]

23/10 Title: TBA

Ramin Golestanian, Max Planck Institute for Dynamics and Self-Organization, Germany  [Webinar]

 

November

6/11 Quantum Error Correction: Dream or Nightmare?

Barbara Terhal, Delft University of Technology, The Netherlands  [Seminar]

20/11 Superconductivity - the universe in a droplet of Mercury

Asle Sudbø, NTNU  [Seminar]

 

December

4/12 Nature-inspired fluidics: Electro-kinetic flow through viscoelastic, charged nanochannels

Peter Berg, University of Alberta, Canada [Seminar]

11/12 Cosmological viscosity

Iver Brevik, NTNU  [Seminar]

 


Current Challenges for Quantum Computing

4 September, 2020

Speaker: David DiVincenzo, RWTH Aachen

Time: 14:15   Place: Webinar

Abstract: We have known for over twenty years that quantum computers would have unique powers for solving certain classes of computational problems. Throughout these twenty years, workers have striven to identify a physical setting in which high-quality qubits can be created and employed in a quantum computing system. Very promising devices have been identified in several different areas of low-temperature electronics, namely in superconductor and in single-electron semiconductor structures (e.g., quantum dots).

Rudimentary efforts at scale-up are presently underway; even for modules of 10 qubits, the complexity of the classical electronic control system becomes one of the main barriers to further progress. The specifications of this control system are now well defined, and are daunting. In this talk I will touch on two aspects of this control problem. First, I indicate the problems with unintended couplings between qubits in multi-qubit structures. For superconducting qubit systems, I show our current methodology for accurately characterizing these couplings. Second, I suggest solutions to the problem of miniaturizing the microwave circulator, using the quantum Hall effect; current circulators take up so much space in existing experiments that they limit the physical scale-up of the systems.


 

Multi-messenger searches for the sources of ultra-high energy cosmic rays and high-energy neutrinos

18 September, 2020

Speaker: Foteini Oikonomou, NTNU

Time: 14:15   Place: Seminar - Realfagbygget R10

Abstract: Ultra-high energy cosmic rays (UHECRs) are the most energetic particles ever observed. They reach energies exceeding 10^20 electronvolts. Their origin is one of the major open questions in astrophysics. A second important messenger of the high-energy universe is neutrinos. The discovery of astrophysical neutrinos with energy up to 10^15 electronvolts in 2013 is one of the scientific breakthroughs of the last decade. Neutrinos are produced in the interactions of high-energy cosmic rays, and thus the two messengers are possibly connected. In this talk, I will give an overview of the latest observations and theoretical insights on the quest for the origin of these messengers, focussing on Active Galactic Nuclei, the most powerful persistent astrophysical objects, as possible sources and prospects for progress in this field with current and upcoming observatories.


 

Biomedical applications of HOT plasmonic nanoparticles

25 September, 2020

Speaker: Lene B. Oddershede, Niels Bohr Institute

Time: 14:15   Place: Seminar - Realfagbygget R10

Abstract: Plasmonic nanoparticles are particularly interesting in a biological context because they have the ability to accumulate in tumor tissue and can easily be transported into cells. Also, plasmonic nanostructures are strongly absorbing in the near infrared (NIR) regime and their associated temperature increase is sensitively dependent on the shape and composition of the structure and on the wavelength of light. Therefore, much effort is put into synthesizing novel nanostructures for optimized interaction with incident light in the NIR regime, which has a relatively long penetration depth into biological tissue. Successful synthesis and characterization of high quality and biocompatible plasmonic colloidal nanoparticles have fostered numerous and expanding applications, especially in biomedical contexts, where such particles are highly promising for general drug delivery and for tomorrow’s cancer treatment.

We demonstrate how to perform laser-controlled heating of plasmonic nanoparticles. This technique is useful for performing laser-induced targeted drug delivery and has potential for treating cancer. We are currently exploring a nanoparticle-based tumor therapy in mouse systems. It is, however, challenging to identify the right nanoparticle which optimally should be non-toxic, strongly absorbing in the NIR, and available in a high and biocompatible quality. To this end, we benchmark different nanoparticles and explore the effect of repeated treatments. The largest challenge, however, extremely relevant for upscaling to human scales, is that the delivery of the particle at the tumor site in the organism must be more efficient than is currently possible. This challenge, as well as possible solutions will be addressed in the presentation.


 

What is new under the Sun?

2 October, 2020

Speaker: Mats Carlsson, UiO

Time: 14:15   Place: Seminar - Realfagbygget R10

Abstract: Solar magnetism lies at the root of most solar and heliospheric physics. The intricate structure and dynamics of the solar field and its influence on the heliosphere represent major quests of (astro) physics, which bear directly on the human environment. The magnetic field is generated by enigmatic dynamo processes in the solar interior, is organized into the complex patterns of activity observed in the solar photosphere, dominates the energetics of the outer solar atmosphere (chromosphere, transition region, corona), regulates the solar wind, and affects the extended heliosphere into the Earth's upper atmosphere.

New ground based solar observatories, newly launched satellites and dramatically increased computational power is transfoming solar physics. In this talk I will go through this development, with a special focus on Norwegian contributions.  


 

Writing Science

12 October, 2020

Speaker: Joshua Schimel, UC Santa Barbara, USA

Time: 14:15   Place: Webinar

Abstract: The value of science grows from our data, but data don’t speak for themselves. I can’t interpret “Photo 51”—Rosalind Franklin’s x-ray diffraction image of DNA—but I do understand Watson and Crick’s diagram of the double helix! As researchers we act as “translators” converting our data into ideas and language. We succeed when our peers read our papers, learn from them, and use them to motivate their own work. That means writing papers that are clear and compelling; telling stories that communicate to our target audiences. To become an effective writer first we need to learn to think from our readers’ perspective—what do they need and value?

Then we can craft papers that work. The first over-arching element of that is story—who is the audience, what is the message, and how to structure it? Second is language—how do you write sentences that are clear and engaging. Then, we can work on polish—weaving together sentences to make the story work. Becoming a successful scientist requires mastering these skills. As professional scientists, we are, thus, professional writers. That calls for perspectives and skills most of us had ignored in our earlier schooling.


 

Disciplining effects of physics jokes

16 October, 2020

Speaker: Maria Berge, Umeå University

Time: 14:15   Place: Seminar - Realfagbygget R10

Abstract: Q: Who was the first electric detective? A: Sherlock Ohms Get it?

This joke’s humour relies on the hearer’s previous knowledge of two usually unrelated facts: that Sherlock Holmes is a fictional detective and that Ohm’s law describes a fundamental relationship between electric current and potential difference. Did you laugh? The primary function of a joke is to make people laugh, but another function can be to create or support intimacy through acknowledging the shared knowledge of an in-group. Physicists have a certain kind of humour and humour has many positive effects: it brings people together and is useful when we interact with each other as tension release. However, we must also carefully consider why we find jokes funny. In this presentation are I will give you several examples of physics jokes but also how humour and jokes may have disciplining effects on an audience.


 

Title: TBA

23 October, 2020

Speaker: Ramin Golestanian, Max Planck Institute for Dynamics and Self-Organization, Germany

Time: 14:15   Place: Webinar


 

Quantum Error Correction: Dream or Nightmare?

6 November, 2020

Speaker: Barbara Terhal, Delft University of Technology, The Netherlands

Time: 14:15   Place: Seminar - Realfagbygget R10

Abstract: We discuss the ideas behind quantum error correction and topological quantum error correction in particular. We review various challenges and efforts to make quantum error correction work in experiment. These challenges include values for noise thresholds and means for fault-tolerant logic: these make quantum error correction fundamentally different from ubiquitous classical error correction.


 

Superconductivity - the universe in a droplet of Mercury

20 November, 2020

Speaker: Asle Sudbø, NTNU

Time: 14:15   Place: Seminar - Realfagbygget R10

Abstract: Superconductivity, first discovered upon cooling droplets of Mercury, is the astonishing phenomenon that a metal loses all of its electrical resistance at a sharply defined temperature. Perhaps even more remarkably, the metal drastically changes its electromagnetic properties at the same sharply defined temperature: the metal completely expulses a magnetic field in the superconducting state. Both the loss of electrical resistance and the expulsion of magnetic field are results of a phase-transition taking place among the electrons of the system.

I will explain what this phase-transition is, and how it leads to the loss of resistance. The most profound aspect of the phenomenon, the expulsion of magnetic field, has a close analog in phase-transitions in the early universe predicted by the Standard Model. I will explain this analogy and will also explain how the search for the Higgs-particle at the Large Hadron Collider at CERN has a table-top analog in superconductors.


 

Nature-inspired fluidics: Electro-kinetic flow through viscoelastic, charged nanochannels

4 December, 2020

Speaker: Peter Berg, University of Alberta, Canada

Time: 14:15   Place: Seminar - Realfagbygget R10

Abstract: The flow of ions and water through soft, nanoscopic domains forms the basis for many processes in biological materials, including biological ion channels. Surprisingly, such systems have rarely been investigated in a theoretical manner for nanofluidic transport in artificial channels of technological applications such as energy harvesting, water desalination, fluidic diodes and fluidic transistors. This talk explores the nonlinear coupling between wall deformation and electro-kinetic transport in a nanochannel with charged walls. Within the framework of non-equilibrium thermodynamics, formulae are derived for the transport properties in terms of Onsager phenomenological coefficients and, subsequently, for energy conversion efficiencies.

We will also discuss how this work relates to polymer-based electro-actuators (‘artificial muscles’) and the functionality of polymer electrolyte membranes, as used in hydrogen fuel cells. The main objective of this presentation is to leave the listener with an appreciation of how nonlinear effects may arise or be amplified in these systems, and how they may be exploited for technology or by nature. This is joint work with M. Matse, M. Eikerling and J. Fuhrmann.

This research is supported by a NSERC Discovery Grant.


 

Cosmological viscosity

11 December, 2020

Speaker: Iver Brevik, NTNU

Time: 14:15   Place: Seminar - Realfagbygget R10

Abstract: I intend first to deal with the fundamental aspects of general relativity (GR), then move on to the Einstein equations in which the viscosity coefficients are plugged in “by hand” in the energy-momentum tensor. Some comparison with observations is given. Perhaps surprisingly, the shear and bulk viscosity coefficients so well-known from ordinary fluid mechanics can be incorporated also in GR in a natural way. Especially, this holds for the bulk viscosity. In the analogous more modern theories of QCD matter, the viscosity coefficients similarly turn up. The viscosity concept is ubiquitous.