Weekly Papers on Quantum Foundations (52)

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.

On signatures of spontaneous collapse dynamics modified single field inflation. (arXiv:1612.09131v1 [astro-ph.CO])

 gr-qc updates on arXiv.org

on 2016-12-31 7:54am GMT

Authors: Shreya BanerjeeSuratna DasK. Sravan KumarT. P. Singh

The observed classicality of primordial perturbations, despite their quantum origin during inflation, calls for a mechanism for quantum-to-classical transition of these initial fluctuations. As literature suggests a number of plausible mechanisms which try to address this issue, it is of importance to seek for concrete observational signatures of these several approaches in order to have a better understanding of the early universe dynamics. Among these several approaches, it is the spontaneous collapse dynamics of Quantum Mechanics which is most viable of leaving discrete observational signatures as collapse mechanism inherently changes the generic Quantum dynamics. We observe in this study that the observables from the scalar sector, i.e. scalar tilt $n_s$, running of scalar tilt $\alpha_s$ and running of running of scalar tilt $\beta_s$, can not potentially distinguish a collapse modified inflationary dynamics in the realm of canonical scalar field and $k-$inflationary scenarios. The only distinguishable imprint of collapse mechanism lies in the observables of tensor sector in the form of modified consistency relation and a blue-tilted tensor spectrum only when the collapse parameter $\delta$ is non-zero and positive.

Authors: J.K. KorbiczJ. Tuziemski

Recently Pikovski et al. have proposed in [I. Pikovski, et al. Nature Phys. 11, 668 (2015)] an intriguing universal decoherence mechanism, suggesting that gravitation may play an important role in the quantum-to-classical transition. Here we analyze information transfer induced by this mechanism. We show that generically, on the short time-scales, gravitational decoherence leads to a redundant information encoding, governed by the energy dispersion and the Fisher information. This leads to a objectivization of the center-of-mass position in the gravitational field. As an example we study thermal coherent states and show certain robustness of the effect with the temperature. Finally, we draw an analogy between our objectivization mechanism and the fundamental problem of point individuation in General Relativity as emphazised by the Einstein’s Hole argument.

Authors: Gilles Cohen-Tannoudji

Our interpretive conjecture is inspired by the epistemology due to Ferdinand Gonseth (1890-1975) who interpreted complementarity as the relationship between profound and apparent reality horizons. It consists, on the one hand, on enlarging the scope of quantum theory to the most profound reality horizon, namely a triply quantum theory of gravitation that would be able to take into account simultaneously as elementary quanta the Planck’s constant, the Planck’s space-time area and the Boltzmann constant, and, on the other hand, on interpreting in terms of generalized complementarity three doubly quantum schemata taking into account by pairs, these three elementary quanta and form the apparent reality horizon.

Authors: Paul K. Townsend

This is a transcription of a conference proceedings from 1985. It reviews the Jordan algebra formulation of quantum mechanics. A possible novelty is the discussion of time evolution; the associator takes over the role of $i$ times the commutator in the standard density matrix formulation, and for the Jordan algebra of complex Hermitian matrices this implies a Hamiltonian of the form $H= i[x,y] + \lambda \mathbb{I}$ for traceless Hermitian $x,y$ and real number $\lambda$. Other possibilities for time evolution in the Jordan formulation are briefly considered.

Authors: M D Reid

Macroscopic realism (MR) specifies that where a system can be found in one of two macroscopically distinguishable states (a cat being dead or alive), the system is always predetermined to be in one or other of the two states (prior to measurement). Proposals to test MR generally introduce a second premise to further qualify the meaning of MR. This paper examines two such models, the first where the second premise is that the macroscopically distinguishable states are quantum states (MQS) and the second where the macroscopcially distinguishable states are localised hidden variable states (LMHVS). We point out that in each case in order to negate the model, it is necessary to assume that the predetermined states give microscopic detail for predictions of measurements. Thus, it is argued that many cat-signatures do not negate MR but could be explained by microscopic effects such as a photon-pair nonlocality. Finally, we consider a third model, macroscopic local realism (MLR), where the second premise is that measurements at one location cannot cause an instantaneous macroscopic change to the system at another. By considering amplification of the quantum noise level via a measurement process, we discuss how negation of MLR may be possible.

Petkov, Vesselin (2016) Is Gravitation Interaction or just Curved-Spacetime Geometry? [Preprint]
Publication date: Available online 23 December 2016
Source:Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics
Author(s): Yemima Ben-Menahem
This paper examines the implications of the PBR theorem for the debate on the reality of the quantum state. The theorem seeks to undermine epistemic interpretations of the quantum state and support realist interpretations thereof, but there remains ambiguity about the precise nature of epistemic interpretations, and thus ambiguity about the implications of the theorem. The aim of this paper is to examine a radical epistemic interpretation that is not undermined by the theorem and is, arguably, strengthened by it. It is this radical interpretation, rather than the one assumed by the PBR theorem, that many epistemic theorists subscribe to. In order to distinguish the radical epistemic interpretation from alternative interpretations of quantum states–in particular, to distinguish it from instrumentalism–a historical comparison of different approaches to the meaning of quantum probabilities is provided. The comparison highlights, in particular, Schrödinger’s work on the nature of quantum probabilities as distinct from probabilities in statistical mechanics, and the implications of this distinction for an epistemic interpretation of probability in the two areas. Schrödinger’s work also helps to identify the difficulties in the PBR definition of an epistemic interpretation and is shown to anticipate the radical alternative that is not undermined by the theorem.
Krause, Décio (2016) Quantum Mechanics, Ontology, and Non-Reflexive Logics. [Published Article or Volume]
Feintzeig, Benjamin H. (2016) On the Choice of Algebra for Quantization. [Preprint]

Author(s): Zhihui Wang, Yali Tian, Chen Yang, Pengfei Zhang, Gang Li, and Tiancai Zhang

An experimental test of the quantum complementarity principle based on single neutral atoms trapped in a blue detuned bottle trap was here performed. A Ramsey interferometer was used to assess the wavelike behavior or particlelike behavior with second π/2rotation on or off. The wavelike behavior or…
[Phys. Rev. A 94, 062124] Published Thu Dec 29, 2016


A quantum universe is expressed as a finite unitary relativistic quantum computer network. Its addresses are subject to quantum superposition as well as its memory. It has no exact mathematical model. It Its Hilbert space of input processes is also a Clifford algebra with a modular architecture of many ranks. A fundamental fermion is a quantum computer element whose quantum address belongs to the rank below. The least significant figures of its address define its spin and flavor. The most significant figures of it adress define its orbital variables. Gauging arises from the same quantification as space-time. This blurs star images only slightly, but perhaps measurably. General relativity is an approximation that splits nature into an emptiness with a high symmetry that is broken by a filling of lower symmetry. Action principles result from self-organization pf the vacuum.

Authors: L. Sriramkumar

By a detector, one has in mind a point particle with internal energy levels, which when set in motion on a generic trajectory can get excited due to its interaction with a quantum field. Detectors have often been considered as a helpful tool to understand the concept of a particle in a curved spacetime. Specifically, they have been used extensively to investigate the thermal effects that arise in the presence of horizons. In this article, I review the concept of detectors and discuss their response when they are coupled linearly as well as non-linearly to a quantum scalar field in different situations. In particular, I discuss as to how the response of detectors does not necessarily reflect the particle content of the quantum field. I also describe an interesting `inversion of statistics’ that occurs in odd spacetime dimensions for `odd couplings’, i.e. the response of a uniformly accelerating detector is characterized by a Fermi-Dirac distribution even when it is interacting with a scalar field. Moreover, by coupling the detector to a quantum field that is governed by a modified dispersion relation arising supposedly due to quantum gravitational effects, I examine the possible Planck scale modifications to the response of a rotating detector in flat spacetime. Lastly, I discuss as to why detectors that are switched on for a finite period of time need to be turned on smoothly in order to have a meaningful response.

Authors: Eleonora Di ValentinoLaura Mersini-Houghton

The 2015 Planck data release tightened the region of the allowed inflationary models. Inflationary models with convex potentials have now been ruled out since they produce a large tensor to scalar ratio. Meanwhile the same data offers interesting hints on possible deviations from the standard picture of CMB perturbations. Here we revisit the predictions of the theory of the origin of the universe from the landscape multiverse for the case of exponential inflation, for two reasons: firstly to check the status of the anomalies associated with this theory, in the light of the recent Planck data; secondly, to search for a counterexample whereby new physics modifications may bring convex inflationary potentials, thought to have been ruled out, back into the region of potentials allowed by data. Using the exponential inflation as an example of convex potentials, we find that the answer to both tests is positive: modifications to the perturbation spectrum and to the Newtonian potential of the universe originating from the quantum entanglement, bring the exponential potential, back within the allowed region of current data; and, the series of anomalies previously predicted in this theory, is still in good agreement with current data. Hence our finding for this convex potential comes at the price of allowing for additional thermal relic particles, equivalently dark radiation, in the early universe.

Kastner, Ruth (2016) A Physical Basis for the Second Law of Thermodynamics: Quantum Nonunitarity. [Preprint]


David Finkelstein was a co-pioneer of the use of topology and solitons in theoretical physics. The author reflects on the great impact Finkelstein had on his research throughout his career. The author provides an application of one of Finkelsteins idea pertaining to the fusion of quantum theory with relativity by utilizing techniques from Loop Quantum Gravity.

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