Category: Seminars

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.

Our visiting researcher Maksym Teslyk is presenting work which is part of his Ph.D. dissertation. It relates to both classical and quantum physical information theory and to general relativity. The picture is Kip Thorne’s black hole visualization from the movie Interstellar.

Abstract:

A spherical system of mass M is represented as a set of Unruh horizons. The approach allows to estimate the total entropy of Unruh radiation from the set and calculate its ratio to the Bekenstein-Hawking entropy. The contribution of mass and spin s of the emitted particles is taken into account. For large values of M, the ratio exhibits susceptibility to the intrinsic degrees of freedom and varies from 0% (s = 0) to 19% (s = 5/2).

Time and place: Thursday Nov. 16th, room PS439 in Pilestredet 35.

Tuesday Nov. 17th we have the pleasure of hearing Noah Oldfield, from Simula Research Lab, presenting results and research question related to his ongoing project. It involves software testing on actual quantum computers. See the abstract below for more details.

Quantum program outputs enable the development of unique quality assurance techniques. Our research focuses on efficiently distinguishing a specialized ideal state vector from the sampled state vector of a program using inference techniques.

To accomplish this, we utilized a hill climbing algorithm for stochastic searches between basis transformations, circumventing the exponential scaling of brute force searches with increased qubit numbers. We conducted tests on a suite of automatically generated faulty programs.

For those programs with state vectors representable in the Hadamard basis, we observed improved testing runtimes and enhanced phase gate fault detection.

Sobolev space formulation of density-functional theory: Solving the v-representability problem.

14th September 13:00, room PS340, building P35.

Density-functional theory is one of the principal methods in physics, chemistry and materials science used for calculating properties of many-body systems based on their electronic structure. It rests on a reformulation of the explicit energy expression in terms of the full quantum state into an implicit energy functional defined for a reduced
quantity, the one-particle density. While considerably reducing the computational complexity, if corresponding approximations are available, this reformulation introduces certain mathematical problems. Most notably, it is not explicitly known which set of densities actually stems from solutions to the quantum many-body problem, i.e., the lowest-eigenvalue solution to the time-independent Schrödinger equation. In this talk a recently found resolution to this so-called “v-representability problem” is presented in the reduced setting of a 1-dim ring system with densities from a Sobolev space.

Monday May 19th we had the pleasure of having Justin Wells visiting our hub. He gave a very interesting presentation on his work within experimental condensed matter physics. It spent quite widely – ranging from implementing qubits in silicon to magnetic properties – and how they are related to ducklings. Despite this rather wide scope, those of us who attended go to hear a presentation which was both accessible and even entertaining.

If you want to learn more about Justin’s research activities, you can read more here:

Ny professor med kvantematerialer som spesiale

https://sites.google.com/site/quantumwells/home

Friday June 9th 2023 we had the pleasure of listening to Tanner Culpitt, postdoc at the Hylleraas Centre, giving a presentation entitled Electronic Structure and Molecular Dynamics in a Strong Magnetic Field. In addition to outlining how such systems can be studied non-perturbatively, he also shared ideas on how quantum computers may be useful in this context.

The seminar was part of a double MatMod seminar, in which also George Hitching from the Faculty of Education and International Studies at OsloMet presented a talk on Moduli of bundles over algebraic curves.

Full abstract for Tanners presentation:

The electronic structure and dynamics of molecules in magnetic fields have historically been treated perturbatively. A perturbative treatment is successful at weaker field strengths, such as those found on Earth. At higher field strengths such as those found in white dwarf stars or neutron stars, a perturbative treatment is inadequate, and new tools are needed to accurately model electronic structure and dynamics. This talk will focus on the theoretical development and application of these tools. Additionally, recent developments in the application of quantum algorithms for the calculation of molecular properties in a magnetic field will be discussed.