# Seminars & Events

**February 12, 2020 at 10:15 **

**Seminar given by Fattah Sakuldee**

ICTQT, UG, Poland

Title: **Kolmogorov consistency as a quantumness witness for external system**

Abstract:

We study the classicality of a finite quantum system, called environment, defined by commutativity of the associate operator algebra, given sequential measurements on the environment. We demonstrate by constructing a scheme of probing from the pure-dephasing-type interaction with a qudit and preparation-evolution-measurement protocol thereon, the weak measurement sequence on the studied environment can be induced and some characteristics of the environment can be extracted from measurement statistics. From the general measurements on the environment, we consider its Kolmogorov consistency, the situation when a shorter length joint probability can be extracted from the longer one by summing the missing all possible intermediate outcomes.

We provide general criteria for equivalence between Kolmogorov consistency of the statistics for arbitrary measurements and commutativity property of operator algebra of the environment and apply the criteria to show explicitly for the induced measurements. As a result, we show that Kolmogorov consistency of the probability can be considered as a quantumness witness for its corresponding operator algebra of the environment if the conditional Hamiltonians are all non-degenerate. For the qubit, the equivalence can be obtained in general if one considers two axes of measurements namely X and Y.

Place: Faculty of Mathematics, Physics and Computer Science, Wita Stwosza 59, Gdansk, room no. 361 (IFTiA).

**February 7, 2020 at 12:15 **

**Seminar given by Stefano Cusumano**

NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR (Pisa), Italy

Title: **Open quantum systems and potential engineering**

Abstract:

As I will shortly move to ICTQT, in this talk I will try to give an overview of my work during the PhD. During this period I worked mainly on open quantum systems, applying collisional models to study both cascade systems (i.e. systems with a chiral propagation of information) and thermodynamic problems. On the other side, I also worked on potential engineering, that is, the design of potential profiles in order to obtain quantum states with specific properties or to perform specific tasks.

Place: Faculty of Mathematics, Physics and Computer Science, Wita Stwosza 59, Gdansk, room no. 361 (IFTiA).

**February 5, 2020 at 10:15 **

**Seminar given by Dominic Horsman**

Université Grenoble Alpes, France

Title: **Quantum compilation using the ZX-calculus**

Abstract:

In this talk I will give an introduction to the use of the ZX calculus of observables as a compilation language for quantum computing.

ZX calculus diagrams comprise a formal re-write language that allows purely diagrammatic equational reasoning for qubit quantum mechanics. I will give a basic introduction to the diagrams (no category theory required), and show how the calculus is especially suited to acting as an ‘intermediate representation’ for quantum compilers. This entails mediating between high-level user workloads/algorithms and qubit-level device specifications. I will go over recent work (both academic and commercial) on circuit optimisation using the calculus, and on its function as design, verification, and optimisation language for error correction. I will finish by discussing insights the use of ZX gives into possible new models of quantum computation.

Place: Faculty of Mathematics, Physics and Computer Science, Wita Stwosza 59, Gdansk, room no. 361 (IFTiA).