The Friday 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. Undergraduate 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 CET but everyone is encourage to arrive at 14:00 CET for some coffee, pastries and mingeling with faculty and students.

In the autumn semester 2020, colloquium lectures are presented in seminar and webinar formats. Seminars are in Realfagbygget R10 (5th floor) and webinars are live streamed via Zoom platform. Please note that all seminars are also streamed via Zoom for those who cannot attend physically.

Autumn 2020 schedule:

* To view abstracts, click on the titles.

* To join online webinars, click on the Zoom meeting.

September

4/9 Current Challenges for Quantum Computing

David DiVincenzo, RWTH Aachen, Germany  [webinar at Zoom meeting, meeting ID: 874 565 5776]

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

Foteini Oikonomou, NTNU, Norway  [CANCELLED]

25/9 Biomedical applications of HOT plasmonic nanoparticles

Lene B. Oddershede, Niels Bohr Institute, Denmark  [webinar at Zoom meeting, Meeting ID: 874 565 5776 ]

October

2/10 What is new under the Sun?

Mats Carlsson, University of Oslo, Norway  [seminar and webinar]

12/10 Writing Science 

(Please note the unusual time: Monday at 16:00 CET)
Joshua Schimel, UC Santa Barbara, USA  [webinar]

16/10 Disciplining effects of physics jokes

Maria Berge, Umeå University, Sweden  [seminar and webinar]

23/10 Making Living Matter from the bottom up

Ramin Golestanian, Max Planck Institute for Dynamics and Self-Organization, Germany and University of Oxford, United Kingdom [webinar]

November

6/11 Quantum Error Correction: Dream or Nightmare?

Barbara Terhal, Delft University of Technology, The Netherlands  [seminar and webinar]

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

Asle Sudbø, NTNU, Norway  [seminar and webinar]

December

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

Peter Berg, University of Alberta, Canada [seminar and webinar]

11/12 Cosmological viscosity

Iver Brevik, NTNU, Norway  [seminar and webinar]

Current Challenges for Quantum Computing

4 September, 2020

Speaker: David DiVincenzo, RWTH Aachen, Germany

Time: 14:15 CET   Place: Webinar at Zoom meeting (Meeting ID: 874 565 5776)

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, Norway

Time: 14:15 CET  Place: CANCELLED

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, Denmark

Time: 14:15 CET  Place: webinar at Zoom meeting (Meeting ID: 874 565 5776)

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, University of Oslo, Norway

Time: 14:15 CET  Place: Seminar at Realfagbygget R10 and webinar

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 (unusual time: Monday at 16:00 CET)

Speaker: Joshua Schimel, UC Santa Barbara, USA

Time: 16:00 CET  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, Sweden

Time: 14:15 CET  Place: Seminar at Realfagbygget R10 and webinar

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.

Making Living Matter from the bottom up

23 October, 2020

Speaker: Ramin Golestanian, Max Planck Institute for Dynamics and Self-Organization, Germany and University of Oxford, United Kingdom

Time: 14:15 CET  Place: Webinar

Quantum Error Correction: Dream or Nightmare?

6 November, 2020

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

Time: 14:15 CET  Place: Seminar - Realfagbygget R10 and webinar

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, Norway

Time: 14:15 CET  Place: Seminar at Realfagbygget R10 and webinar

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 CET  Place: Seminar at Realfagbygget R10 and webinar

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 CET  Place: Seminar at Realfagbygget R10 and webinar

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.