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Reconstructing quantum theory from diagrammatic postulates
A reconstruction of finite-dimensional quantum theory where all of the postulates are stated entirely in diagrammatic terms, making them intuitive, and necessary additional axioms for a process theory to correspond to the Hilbert space model are characterised.
Deriving Grover's lower bound from simple physical principles
Surprisingly, it is shown that the quadratic lower bound holds regardless of the order of interference, which means that post-quantum interference does not imply a computational speed-up over quantum theory.
Unscrambling the omelette of causation and inference: The framework of causal-inferential theories
It is argued that if one can identify axioms for a realist causal-inferential theory such that the notions of causation and inference can differ from their conventional (classical) interpretations, then one has the means of defining an intrinsically quantum notion of realism, and thereby a realists representation of operational quantum theory that salvages the spirit of locality and of noncontextuality.
Generalised phase kick-back: the structure of computational algorithms from physical principles
The advent of quantum computing has challenged classical conceptions of which problems are efficiently solvable in our physical world. This motivates the general study of how physical principles…
A no-go theorem for theories that decohere to quantum mechanics
- Ciarán M. Lee, John H. Selby
- Philosophy, PhysicsProceedings of the Royal Society A: Mathematical…
- 25 January 2017
This work asks whether there exists an operationally defined theory superseding quantum theory, but which reduces to it via a decoherence-like mechanism and proves that no such post-quantum theory exists if it is demanded that it satisfy two natural physical principles: causality and purification.
A no-go theorem on the nature of the gravitational field beyond quantum theory
Recently, table-top experiments involving massive quantum systems have been proposed to test the interface of quantum theory and gravity. In particular, the crucial point of the debate is whether it…
Entanglement is Necessary for Emergent Classicality in All Physical Theories.
It is shown that any theory with a classical limit must contain entangled states, thus establishing entanglement as an inevitable feature of any theory superseding classical theory.
Leaks: Quantum, Classical, Intermediate and More
It is shown that defining a notion of purity for processes in general process theories has to make reference to the leaks of that theory, a feature missing in standard definitions; hence, a refined definition is proposed and the resulting notion ofurity for quantum, classical and intermediate theories is studied.
Oracles and Query Lower Bounds in Generalised Probabilistic Theories
It is shown that if a classical computer requires at least n queries to solve a learning problem, then the corresponding “no-information” lower bound in theories lying at the kth level of Sorkin’s hierarchy is n, which leaves open the possibility that quantum oracles are less powerful than general probabilistic oracles.
Characterization of Noncontextuality in the Framework of Generalized Probabilistic Theories
It is argued that simplex-embeddability constitutes an intuitive and freestanding notion of classicality for GPTs, which has applications to witnessing nonclassicality in prepare-measure experiments.