The question how quantum theory arises from physical principles has been of interest to the quantum foundations community for decades. At Quriosity, we investigate whether we can formulate a physical principle or a collection thereof according to which quantum theory is optimal.
Associated PIs: Mirjam Weilenmann
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Quantum theory, with its seemingly superluminal influences, defies our classical understanding of causality. Rather than lamenting this state of affairs, the goal of quantum causal modelling is to instead pin down a natively quantum account of causality, take it as fundamental, and see whether that helps us understanding the theory better, both in its foundations and in its applications. In Quriosity, we explore the algebraic structures underpinning quantum causal influences, as well as the (troubled) relationship between the quantum-informational and the relativistic accounts of causality.
Associated PIs: Augustin Vanrietvelde
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Non-local correlations are the quantum resource that lies at the core of Bell’s theorem and are useful for instance in the context of cryptographic tasks such as randomness generation and key distribution. At Quriosity, we find ways to strengthen non-local correlations in ways that are interesting conceptually, e.g. for exploring beyond-quantum theories, or that make them more useful for cryptographic tasks. We further explore the advantages and limitations of non-local correlations generated in more complicated setups involving a network structure.
Associated PIs: Mirjam Weilenmann
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Most physical quantities pertaining to a system are only meaningful when described with respect to a certain reference frame. But the reference frame is itself a physical system, which must ultimately be described in quantum terms just as much as the rest of the world. Research on quantum reference frames aims at making sense of this idea, as well as providing an account of transformations from one quantum reference frame to another. In Quriosity, we focus on the mathematical and conceptual aspects of quantum reference frames: how they relate to symmetries, and what their operational meaning could be.
Associated PIs: Augustin Vanrietvelde
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Certain correlations in a Bell-test can be shown to be produced by a unique (up to local isometries) quantum system. Thus, observations of these correlations provides a (device-independent) proof that the hardware is producing a certain quantum system. Such settings are known as self-tests and provide one method to analyse the properties of systems via their correlations, e.g. for applications to cryptography or information processing. At Quriosity we are developing new methods to construct self-tests of states that exhibit particular properties of interest and exploring self-tests of multipartite systems.
Associated PIs: Peter Brown
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