Upper bounds on the rate in device-independent quantum key distribution

Speaker: Karol Horodecki (ICTQT, University of Gdansk) Abstract Quantum key distribution (QKD) is a method that distributes a secret key to a sender and receiver by the transmission of quantum particles (e.g. photons). Device-independent quantum key distribution (DIQKD) is a version of QKD with a stronger notion of security, in that the sender and receiver base […]

Speaker: Andy Chia (NUS Singapore) Abstract Abstract: The amplification of light in quantum theory has a long history, with research devoted mostly to the linear (i.e. one-photon) regime due to its simplicity [1]. However, nonlinear amplification has also received some interest since the 1960s. One obvious generalisation of linear/one-photon amplification is to allow for two […]

Speaker: Hippolyte Lazourenko-Dourdent  (Institut Néel / Université Grenoble Alpes) Abstract While the standard formulation of quantum theory relies on a fixed background causal structure, one can consider a more general framework - based on quantum theory - where the causal structure is indefinite (the "process matrix formalism"). Interestingly, the tools introduced to identify causal indefiniteness - causal […]

Speaker: Maharshi Ray (Centre for Quantum Technologies, National University of Singapore) Abstract We discuss schemes to certify local quantum systems via self-testing and dimension witnessing. This work leverages the graph-theoretic framework for contextuality introduced by Cabello, Severini, and Winter, combined with tools from combinatorial optimisation that guarantee the unicity of optimal solutions. We first show […]

Speaker: Marek Czachor (Gdańsk University of Technology) Abstract Bell's theorem is supposed to exclude all local hidden-variable models of quantum correlations. However, an explicit counterexample shows that a new class of local realistic models, based on generalized arithmetic and calculus, can exactly reconstruct rotationally symmetric quantum probabilities typical of two-electron singlet states. Observable probabilities are […]

Speaker: Roberto D. Baldijão (State University of Campinas, IQOQI Vienna) Abstract Quantum Darwinism posits that the emergence of a classical reality relies on the spreading of classical information from a quantum system to many parts of its environment. But what are the essential physical principles of quantum theory that make this mechanism possible? We address this […]

Speaker: Marius Krumm (IQOQI Vienna and University of Vienna Abstract Nonlocality, as demonstrated by the violation of Bell inequalities, enables device-independent cryptographic tasks that do not require users to trust their apparatus. In this presentation, we consider devices whose inputs are spatiotemporal degrees of freedom, e.g. orientations or time durations. Without assuming the validity of […]

Speaker: Otavio A. D. Molitor, ICTQT Abstract With the study of ever decreasing systems, it's paramount to understand thermodynamic phenomena in ultra-small scales, where quantum phenomena live. This gave origin to the flourishing research field known as quantum thermodynamics. One of its main branches, which deals with quantum systems undergoing thermodynamic cycles, is called quantum […]

Speaker: Labeled graph framework for unique games Abstract We present a framework in which unique games are represented in the form of edge-labelings of graphs. We define an equivalence relation which preserves both classical and quantum values of games. We also show how the classical value of the game depends on the properties of the […]

Speaker: Marco Erba, Università degli Studi di Pavia, INFN   Abstract A standardly adopted notion of classicality is the following: a system is deemed classical if its set of states is a simplex. Also, it is traditionally excluded that a classical theory may admit of entangled states. This is of course the case for classical theory (CT). […]