[Alta-Logic] Two talks

[Ben MacAdam]

Sorry for the mix-up:

Date: 19 June, Wednesday
Time: 12:00pm - 1:30pm
Venue: MS337

The talk will be presented by Stefano Gogoiso, a post doc working with Bob Coecke at the University of Oxford.
Title: A Process-Theoretic Church of the Larger Hilbert Space
Abstract: We show how to reconstruct a process theory of local systems starting from a global theory of reversible processes on a single global system, by using the purification principle. In such a process theory, local systems are not given, but rather “emerge” as the global system is decomposed into subsystems. Local systems thus have specific identities and their composition is naturally limited by structural constraints, a behaviour which we formalise by defining symmetric partially-monoidal categories. We reconstruct quantum theory from the global theories of unitary groups acting on projective Hilbert spaces.
https://arxiv.org/abs/1905.13117


Date: 20 June, Thursday
Time: 11:00am - 1:30
Venue: MS337
This talk will be presented by Nicola Pinzani, a PhD student working with Bob Coecke at the University of Oxford.
Title: Categorical Semantics for Time Travel
Abstract: We introduce a general categorical framework to reason about quantum theory and other process theories living in spacetimes where Closed Timelike Curves (CTCs) are available, allowing resources to travel back in time and provide computational speedups. Our framework is based on a weakening of the definition of traced symmetric monoidal categories, obtained by dropping the yanking axiom and the requirement that the trace be defined on all morphisms. We show that the two leading models for quantum theory with closed timelike curves—namely the P-CTC model of Lloyd et al. and the D-CTC model of Deutsch—are captured by our framework, and in doing so we provide the first compositional description of the D-CTC model. Our description of the D-CTC model results in a process theory which respects the constraints of relativistic causality: this is in direct contrast to the P-CTC model, where CTCs are implemented by a trace and allow post-selection to be performed deterministically
https://arxiv.org/abs/1902.00032
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