Category: Seminars

It is a pleasure to invite you all a seminar with prof. Eva Lindroth from Stockholm University.

Her background is with atomic, molecular and optical physics. Her contributions to the field is diverse and impressive. She is also a member of the Royal Swedish Academy of Sciences, Vice Chair for the class of Physics.

In this seminar she will tell us about the Nobel prize – naturally with emphasis on the physics prize. We will hear about how the laureates are elected. And she will tell us about particularly famous laureates such as Curie, Einstein and Meitner. Meitner is, perhaps, the most grave omission ever made when it comes to the physics prize.

Much of Eva’s research is very closely related to this year’s and last year’s Nobel prizes, the latter being awarded within the field of attosecond physics with her fellow Swede Anne L’Houllier as one of the recipients. This year’s prize is, of course, particularly interesting to our colleges at the AI group – highlighting the close connection between physics and AI.

Time: Wednesday 30th from 12.00

Place: PS439 in P35 (We will try to find a larger room if need be)

On behalf of the MatMod group and the Quantum Hub,

Sølve

We invite all colleagues interested in open quantum systems and quantum information to the upcoming seminar by Frederik vom Ende from Freie Universität Berlin (please see the title and abstract below). The seminar will take place next Thursday, October 10th, at 13:00 in P35-PS439. Lunch will be provided on-site.

Quantum-Dynamical Semigroups and the Church of the Larger Hilbert Space

The idea underlying open systems theory is to describe the evolution of non-isolated systems—at least approximately—via a differential equation ρ'(t)=Lρ(t) with L of a special form, called Lindblad- or GKSL-form. This is, however, not the only way to tackle this problem; another successful approach is to consider the system coupled to its environment, and then extract the system’s dynamics by tracing out the environment from the combined unitary evolution. While the physics literature features well-known approximations which guarantee when these two descriptions are compatible, in this talk we will investigate under what conditions they can match precisely: Our main result is that GKSL-dynamics can be written exactly as the reduced evolution of system plus some environment if and only if the environment is infinite-dimensional with an overall unbounded Hamiltonian. In doing so we obtain a second-order Taylor-approximation for bounded system-environment Hamiltonians, with some familiar coefficients.

It is a true pleasure to invite you to a seminar with our guest researchers Yves Rezus. Yves is spending this academic year on sabbatical and has chosen to come to us!

Do come and listen!

Abstract:

Encounters with single-quantum emitters

Yves Rezus

Amsterdam University of Applied Sciences (AUAS)

Single-quantum emitters are the smallest possible light sources. They consist of trapped atoms, molecules or engineered nanostructures, which emit one photon at a time. Research in single-quantum emitters has taken an enormous surge in the past few decades, leading to applications ranging from biological imaging to quantum computing.

In this talk I will give an experimental perspective on single-quantum emitters, focusing on what it takes to observe them in the laboratory and to exploit their properties in real-world applications. Along the way we will see what single-quantum emitters can teach us about fundamental quantum mechanics.

This Friday, 28th of June, we have the pleasure of hosting Anders Kvellestad, from the University of Oslo, who gave us an introduction to QBism!

That is a relatively new interpretation of quantum mechanics that emphasizes the role of the observer in defining quantum states. QBism, or Quantum Bayesianism, interprets quantum probabilities as personal beliefs about the outcomes of measurements, rather than objective properties of physical systems.

His lecture was thought-provoking and sparked a lively discussion with numerous questions from the audience (see photo). We are looking forward to his second seminar after the summer break, where he will delve deeper into the intricacies of QBism.

It is a pleasure to invite to this years first Quantum seminar.

Perdo Ribero from the University of Lisbon is presently our guest at the Hub. Upcoming Monday, the 22^nd, he will tell us a bit about one of his research interests, namely Random matrices on dissipative quantum dynamics

Time and place: Room PS523 in P35, OsloMet. 12.00-13.00.

Abstract:

Understanding the dissipative dynamics of complex quantum systems is essential to describe quantum matter at large time scales. However, even within a simplified Markovian description, studying the spectral and steady-state properties of Lindblad operators remains a challengiing task. In this talk, we present some novel insights into universal features of generic open quantum systems under Markovian dissipation by using ensemble averaging based on (non-Hermitian) random matrices. We examine three representative cases: quadratic Liouvilians, dissipative SYK models, and fully random Liouvilian operators. For this last example, we present a recent systematic classification of many-body Lindblad superoperators based on the properties of the Lindbladian under antiunitary symmetries and unitary involutions.