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The quantum flip

By Giulio Chiribella and Zixuan Liu.  Pre-publication link. At the microscopic level, the fundamental laws of physics are time symmetric: every fundamental process admits a time-reversal, which describes the same physics seen from the point of view of an observer with an inverted arrow of time. In stark contrast, our everyday experience and our laboratory practice …

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Quantum Reference Frames

When we think operationally about space and time, we usually assume that the objects we use as reference frames are classical systems – like a macroscopic heavy ruler or a clock with sharply defined hands.  Quantum reference frames have recently been introduced as a formalism to describe physics when rulers and clocks are assumed to …

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Witnessing non-classicality beyond quantum theory

Witnessing non-classicality beyond quantum theory. Published in Physical Review D. By Chiara Marletto (QISS Oxford Physics) and Vlatko Vedral (QISS Oxford Physics). Popular Summary: This paper provides the strongest theoretical basis for recently proposed experiments to test quantum effects in gravity, achieving the remarkable result that such experiments, if performed successfully, would rule out all …

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Quantum information and the arrow of time

Quantum information and the arrow of time. Andrea Di Biagio (QISS Rome), Pietro Donà, Carlo Rovelli (QISS Marseille)  pre-published at  Popular Summary: Standard formulations of quantum mechanics feature two distinct laws describing how the state of a quantum system changes in time. The first law, the Schrödinger equation, is smooth and time-reversal symmetric. By looking …

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Wigner’s friend through experiment: relativity of facts

[1] Facts are relative, Caslav Brukner, Nature Physics volume 16, pages 1172–1174 (2020),  [2] A no-go theorem for the persistent reality of Wigner’s friend’s perception (under review) Popular summary:  The quantum measurement problem is one of the most fundamental in quantum theory and its putative solutions are at the centre of controversy over their alternative interpretations. …

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New Scientist — Why Quantum is Relative

Quantum weirdness isn’t weird – if we accept objects don’t exist We can grasp the truth about the quantum world, as long as we abandon our most cherished assumption about what’s real and what’s not Further details here