Device-independent quantum cryptography in the multipartite scenario

Speaker: Gláucia Murta, Heinrich-Heine-Universitat Dusseldorf Abstract Going beyond the simple two-party scenario of quantum key distribution, we consider N parties who wish to certify security against a potential eavesdropper in a cryptographic task. Moreover, we consider the very adversarial scenario in which the parties make no assumption about the underlying quantum system or the internal […]

Speaker: Máté Farkas, UG/ICTQT Abstract As quantum technologies advance, the certification of high-dimensional quantum devices becomes more and more relevant. This is essential both for verifying the outcome of quantum computations, and for guaranteeing the security of cryptographic devices. In this talk, I will focus on the certification of quantum measurement devices performing measurements in […]

Speaker: David Schmid, University of Waterloo / Perimeter Institute Abstract A standard approach to quantifying resources is to determine which operations on the resources are freely available and to deduce the ordering relation among the resources that these operations induce. If the resource of interest is the nonclassicality of the correlations embodied in a quantum state, […]

Speaker: Akshata Shenoy ICTQT Abstract Modern communication strives towards provably secure systems which can be widely deployed. Quantum key distribution provides a methodology to verify the integrity and security of a key exchange based on physical laws. However, physical systems often fall short of theoretical models, meaning they can be compromised through uncharacterized side-channels. The […]

Speaker: Jan Tuziemski, Stockholm University Abstract Recent theoretical and experimental studies have shown significance of quantum information scrambling for problems encountered in high-energy physics, quantum information, and condensed matter. Due to complexity of quantum many-body systems it is plausible that new developments in this field will be achieved by experimental explorations. Therefore, a better theoretical understanding […]

Speaker: Patryk Lipka-Bartosik, University of Bristol Abstract The standard benchmark for teleportation is the average fidelity of teleportation and according to this benchmark not all states are useful for teleportation. It was recently shown, however, that all entangled states lead to nonclassical teleportation, with there being no classical scheme able to reproduce the states teleported to […]

Speaker: Markus Frembs Abstract Contextuality is a key feature of quantum mechanics, as was first brought to light by Bohr and later realised more technically by Kochen and Specker. Isham and Butterfield put contextuality at the heart of their topos-based formalism and gave a reformulation of the Kochen-Specker theorem in the language of presheaves. Here, […]

Speaker: Felix Leditzky, IQC, University of Waterloo / Perimeter Institute Abstract Communication networks have multiple users, each sending and receiving messages. A multiple access channel (MAC) models multiple senders transmitting to a single receiver, such as the uplink from many mobile phones to a single base station. The optimal performance of a MAC is quantified by […]

Speaker: Felix Huber, ICFO (Castelldefels) Abstract The study of polynomials that are positive on certain sets has a rich history, going back to Hilbert's seventeenth problem. Here we will look at multivariate polynomials (and more generally, contractions) that have matrices as their variables. These are constructed such that they yield positive semi-definite expressions whenever they […]

Speaker: Katarzyna Roszak, Wroclaw University of Science and Technology Abstract The problem of detecting entanglement between a qubit and its environment is known to be complicated [1]. To simplify the issue, we study the class of Hamiltonians that describe the interacting system in such a way that the resulting evolution of the qubit alone is […]