This is a list of this week’s papers on quantum foundations published in various journals or uploaded to preprint servers such as arxiv.org and PhilSci Archive.

Reflections on the renormalization procedure for gauge theories. (arXiv:1604.06257v1 [hep-th])

on 2016-4-22 2:48am GMT

Authors: Gerard t Hooft

Various pieces of insight were needed to formulate the rules for working with gauge theories of the electro-magnetic, weak and strong forces. First, it was needed to understand how to formulate the Feynman rules. We had to learn that there are many different ways to derive them, and it was needed to know how different formulations of the gauge constraint lead to the same final results: the calculated values of the scattering amplitudes. The rules for dealing with the infinities that had to be subtracted were a big challenge, culminating in the discovery of the Becchi-Rouet-Stora-Tyutin symmetry. Fond recollections of the numerous discussions the author had with Raymond Stora on this topic are memorised here. We end with some reflections on the mathematical status of quantum field theories, and a letter sent by Stora to the author

Quantum Holonomy Theory and Hilbert Space Representations. (arXiv:1604.06319v1 [gr-qc])

on 2016-4-22 2:48am GMT

Authors: Johannes Aastrup, Jesper M. Grimstrup

We present a new formulation of quantum holonomy theory, which is a candidate for a non-perturbative and background independent theory of quantum gravity coupled to matter and gauge degrees of freedom. The new formulation is based on a Hilbert space representation of the QHD(M) algebra, which is generated by holonomy-diffeomorphisms on a 3-dimensional manifold and by canonical translation operators on the underlying configuration space over which the holonomy-diffeomorphisms form a non-commutative C*-algebra. A proof that the state exist is left for later publications.

Single electron relativistic clock interferometer. (arXiv:1604.06217v1 [gr-qc])

on 2016-4-22 2:48am GMT

Authors: Pavel Bushev, Jared H. Cole, Dmitry Sholokhov, Nadezhda Kukharchyk, Magdalena Zych

Although time is one of the fundamental notions in physics, it does not have a unique description. In quantum theory time is a parameter ordering the succession of the probability amplitudes of a quantum system, while according to relativity theory each system experiences in general a different proper time, depending on the system’s world line, due to time to time dilation. It is therefore of fundamental interest to test the notion of time in the regime where both quantum and relativistic effects play a role, for example, when different amplitudes of a single quantum clock experience different magnitudes of time dilation. Here we propose a realization of such an experiment with a single electron in a Penning trap. The clock can be implemented in the electronic spin precession and its time dilation then depends on the radial (cyclotron) state of the electron. We show that coherent manipulation and detection of the electron can be achieved already with present day technology. A single electron in a Penning trap is a technologically ready platform where the notion of time can be probed in a hitherto untested regime, where it requires a relativistic as well as quantum description.

on 2016-4-22 2:48am GMT

Authors: Daniel Valente, Frederico Brito, Thiago Werlang

The concepts of work and heat in the quantum domain, as well as their interconversion principles, are still an open debate. We have found theoretical evidence that a single photon packet is capable of extracting work from a single two-level system (TLS). More importantly, this effect is found for a photon as it is spontaneously emitted, therefore carrying only heat away from the emitter. This is the most elementary process in which heat is converted into work, requiring not more than two off-resonance atoms for that purpose. From a more practical point of view it is found that, surprisingly, work can be extracted from a TLS in a completely passive initial state. The process is cyclic in the sense that the TLS initial and final states are equal. The state of the TLS remains passive throughout the interaction time with the single-photon packet. The physical meaning of the work performed by the TLS is found to be a dynamical change in the color of the photon during the reemission process. All our predictions are, in principle, measurable within state-of-the-art experiments.

physics.hist-ph updates on arXiv.org

on 2016-4-22 2:48am GMT

Authors: Ramin Zahedi

In part I (pp. 1-10) of this article, I provide an analysis and overview of some notable definitions and works concerning discrete physics (a.k.a. digital philosophy, digital physics) that propose discrete, finite and deterministic characteristics for the physical world. Particular attention is given to theories which suggest cellular automata as the basis of a deterministic model for the physical reality.

In part II (the main part, pp.11-97, Ref. [37]) of this article, I’ve presented a new axiomatic approach based on the ring theory and Clifford algebras. Using this (primary) mathematical approach, by linearization (and simultaneous parameterization), followed by first quantization of the relativistic energy-momentum relation, a unique set of the general relativistic (single-particle) wave equations are derived directly. These equations are shown to correspond to certain massive forms of the laws governing the fundamental forces of nature, including the Gravitational, Electromagnetic (Maxwell) and Nuclear (Yang-Mills) field equations (formulated solely in 1+3 dimensions), and also the (half-integer spin) single-particle wave equations such as the Dirac equation (formulated solely in 1+2 dimensions). In addition, it is shown that the “massive” Lagrangian density of the obtained Yang-Mills fields could be also locally gauge invariant – where these fields are formally re-presented on a background spacetime with certain complex torsion generated by the rest mass of the field carrier particle. Moreover, based on the definite mathematical structure of general relativistic particle wave equations derived and also the assumption of chiral symmetry of source-free cases of these fields, it is proven that the universe cannot have more than four spacetime dimensions. On this basis, it is also shown that magnetic monopoles (in contrast with electric monopoles) could not exist in nature.

An impossibility theorem for parameter independent hidden variable theories

on 2016-4-22 12:51am GMT

Publication date: May 2016

**Source:**Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics, Volume 54

Author(s): Gijs Leegwater

Recently, Roger Colbeck and Renato Renner (C&R) have claimed that ‘[n]o extension of quantum theory can have improved predictive power’ (Colbeck & Renner, 2011, 2012b). If correct, this is a spectacular impossibility theorem for hidden variable theories, which is more general than the theorems of Bell (1964) and Leggett (2003). Also, C&R have used their claim in attempt to prove that a system׳s quantum-mechanical wave function is in a one-to-one correspondence with its ‘ontic’ state (Colbeck & Renner, 2012a). C&R׳s claim essentially means that in any hidden variable theory that is compatible with quantum-mechanical predictions, probabilities of measurement outcomes are independent of these hidden variables. This makes such variables otiose. On closer inspection, however, the generality and validity of the claim can be contested. First, it is based on an assumption called ‘Freedom of Choice’. As the name suggests, this assumption involves the independence of an experimenter׳s choice of measurement settings. But in the way C&R define this assumption, a no-signalling condition is surreptitiously presupposed, making the assumption less innocent than it sounds. When using this definition, any hidden variable theory violating parameter independence, such as Bohmian Mechanics, is immediately shown to be incompatible with quantum-mechanical predictions. Also, the argument of C&R is hard to follow and their mathematical derivation contains several gaps, some of which cannot be closed in the way they suggest. We shall show that these gaps can be filled. The issue with the ‘Freedom of Choice’ assumption can be circumvented by explicitly assuming parameter independence. This makes the result less general, but better founded. We then obtain an impossibility theorem for hidden variable theories satisfying parameter independence only. As stated above, such hidden variable theories are impossible in the sense that any supplemental variables have no bearing on outcome probabilities, and are therefore trivial. So, while quantum mechanics itself satisfies parameter independence, if a variable is added that changes the outcome probabilities, however slightly, parameter independence must be violated.

Quantum Mechanics as Generalised Theory of Probabilities

PhilSci-Archive: No conditions. Results ordered -Date Deposited.

on 2016-4-21 8:18pm GMT

Bitbol, Michel (2014) Quantum Mechanics as Generalised Theory of Probabilities. [Published Article]

What is orthodox quantum mechanics?

PhilSci-Archive: No conditions. Results ordered -Date Deposited.

on 2016-4-21 8:13pm GMT

Wallace, David (2016) What is orthodox quantum mechanics? [Preprint]

PhilSci-Archive: No conditions. Results ordered -Date Deposited.

on 2016-4-18 6:19pm GMT

Boge, Florian (2016) ψ-Epistemic Models, Einsteinian Intuitions, and No-Gos. A Critical Study of Recent Developments on the Quantum State. [Preprint]

What the Humean cannot say about entanglement

PhilSci-Archive: No conditions. Results ordered -Date Deposited.

on 2016-4-18 5:56pm GMT

Dewar, Neil (2016) What the Humean cannot say about entanglement. [Preprint]