Dec 14, 2017 at 9:00 to Dec 15, 2017 at 18:00

University College of London, London, UK

University College of London, London, UK

**Organizers:** BRCP members Carlos Zapata (c.zapata.carratala@gmail.com), Flavio Del Santo and Uther Shackerley-Bennett

**Description:** An informal meeting where topics revolving around fundamental aspects of physics, science in general and mathematics can be discussed and debated openly. We expect a diverse range of topics, anything from philosophy of physics or foundations of mathematics to new experimental frontiers or the socioeconomic structure of academia. In addition to deep discussions, this event aims to provide an opportunity to network with other like-minded people based in the UK or nearby countries.

**Dates:** 14th-15th of December (follow-up informal BRCP meeting 16th-17th of December)

**Venue:** University College of London main campus

**Registration:** If you would like to participate as a speaker, please send the details listed below

Name:

(optional) Position and Institution:

Title of your talk:

Abstract of your talk:

to (c.zapata.carratala@gmail.com) by the 17th of November. The list of talks will be confirmed by the 20th of November. Attendance to the event is free and open to everyone, but for organisational purposes we ask you to confirm your attendance via email (c.zapata.carratala@gmail.com) by the 8th of December.

**Schedule:**

Thursday @ Physics and Astronomy, Room E1.

09:00-09:30 Opening session

09:30-10:15 Talk 1

10:15-11:00 Talk 2

11:00-11:15 Coffee break

11:15-12:00 Talk 3

12:00-15:00 Lunch break and discussions

15:00-15:45 Talk 4

15:45-16:30 Talk 5

16:30-16:45 Coffee break

16:45-17:30 Talk 6

17:30-19:30 Discussions

19:30-onwards Dinner and “meta” discussions

Friday @ 20 Bedford Way, Institute of Education, Room 603

09:30-10:15 Talk 7

10:15-11:00 Talk 8

11:00-11:15 Coffee break

11:15-12:00 Talk 9

12:00-15:00 Lunch break and discussions

15:00-15:45 Talk 10

15:45-16:30 Talk 11

16:30-16:45 Coffee break

16:45-17:30 Talk 12

17:30-19:30 Discussions

19:30-onwards Dinner and “meta” discussions

**List of Registered Participants:**

Carlos Zapata (University of Edinburgh)

Flavio Del Santo (University of Vienna)

Uther Shackerley-Bennett (University College London)

**List of Talks:**

Talk 1 - Flavio Del Santo - On the Nature of Quantum Superposition and Entanglement

It is today well known that the counterintuitive features of quantum mechanics, specifically superposition principle or quantum entanglement, paved the way to new possibilities. The advent of quantum information theory, together with development of modern techniques, allowed to exploit genuine quantum effects to achieve novel outstanding results, such as quantum computing, quantum cryptography or quantum communication. But, are coherent superpositions and entanglement genuinely different phenomena? In fact, although a few would question that quantum entanglement represents a special case of superposition (between different Hilbert spaces), it still is unclear whether, under certain circumstances, a “mere” superposition can be represented as an entangled state, and if this is meaningful at all. There are indeed cases in which superselection rules, imposed to satisfy physical constraints, can “create” an entangled state with vacuum. This is what is commonly referred to as single-particle entanglement [1]. In my talk I will explore this possibility, showing that single particle entanglement can be operationally conceived and, as such, it can undergo experimental tests. I will moreover present a recently proposed communication task, which, making use of single-particle entanglement (i.e. spatial superposition of a single particle), can violate a fundamental classical bound (i.e. a Bell-like inequality) [2]. This should convince that, given a suitable operational definition of entanglement, quantum superposition principle and quantum entanglement fundamentally have a common nature. References: [1] Van Enk, S. J. “Single-particle entanglement. Physical Review A 72.6(2005): 064306.[2] Del Santo, F. and B. Daki ́c. “Two-way communication with a single quantum particle”. Arxiv preprint: https://arxiv.org/abs/1706.08144.

Talk 2 - Vaclav Zatloukal - Differential geometry with shape tensor

I will study differential geometry of embedded manifolds by means of the shape tensor. It seems natural to regard this three-index object as the fundamental quantity for description of the geometric properties of manifolds, as it captures both extrinsic and intrinsic curvature (namely, the Riemann tensor is obtained as a simple algebraic function of the shape tensor). I will point out that although in gravitational physics only intrinsic features of the manifold are relevant, extra structure of fibre bundles is added as soon as electromagnetism, and/or weak and strong forces are to be discussed. This leads to the question whether the latter 'Yang-Mills theories' could in fact be obtained from the extrinsic part of the total curvature, and how the gauge potentials and Yang-Mills field strengths relate to the shape tensor and its combinations. The shape tensor is most efficiently handled with the mathematical formalism of geometric algebra, which I briefly present, and compare to traditional tensor-calculus methods.

Talk 3 - Carlos Zapata - Quantum Dynamics and Quantum Relativity

In this talk I will introduce the abstract notions of observer, dynamics and relativity in physical theories in a mathematically rigorous way. After a brief recap of the case of classical theories and traditional Einsteinian relativity I will try to draw a parallel with quantum systems and try to outline the basic principles of a theory of quantum relativity. It should be noted that this will not be a quantization of classical relativity/gravity but rather a more conceptual approach to the fundamental question of how observers measuring a quantum system agree that they are both describing the same reality.

Talk 4 - Pierre Martin-Dussaud - Relational Quantum Mechanics

This talk will be an introduction to the relational interpretation of quantum mechanics. This interpretation was first presented by Carlo Rovelli more than twenty years ago. To put it in a nutshell, this approach states that "quantum mechanics is a theory about the physical description of physical systems relative to other systems, and this is a complete description of the world". We will explain the practical meaning of this headline, and try to question the posterity of it.

Talk 5 - Thao (TK) P. Le - The Emergence of Classicality from Quantum Mechanics

If quantum mechanics describes things that are small, and classical mechanics describes things are big, what happens to the physics of the things in-between? Given the assumption that all quantum states are equally likely to occur, and that many quantum states involve some kind of quantum superposition, why is that we don’t see macroscopic objects in quantum superposition? There have been many suggestions and theories to describe the quantum-to-classical transition, and the correct answer (if there is any) is still unclear, although it is widely accepted that decoherence theory plays a role. In this talk, I will introduce a number of different approaches to explaining emergent classicality, including quantum Darwinism and the relative state (many worlds) interpretation.

Talk 6 - Claudia Clarke - Dissipation production in a closed two-level quantum system as a test of the obversibility of the dynamics

Irreversible behaviour is traditionally associated with open stochastic dynamical systems, but an asymmetry in the probabilistic state of a closed deterministic system can similarly lead to a disparity in the likelihood of particular forward and the corresponding backward behaviour when initiated from a specified time. Such a comparison is a test of a property denoted obversibility, which may be quantified in terms of dissipation production as a measure of irreversibility. We here discuss the procedure needed to evaluate dissipation production in a simple, deterministic two-state quantum system and then provide numerical results for example situations. We consider cases that both do and do not fulfil an Evans-Searles Fluctuation Theorem for the dissipation production. As the procedure is applicable to open quantum systems too, we also speculate on the associated dissipation production in these situations and its implications for our understanding of irreversibility and the emergence of the Second Law, with attention to the role of measurement.

Talk 7 - Johannes Kleiner - TBD

Talk 8

Talk 9

Talk 10

Talk 11

Talk 12