Journal of Physics: Conference Series
ISSN / EISSN : 17426588 / 17426596
Current Publisher: SPIE-Intl Soc Optical Eng (10.1117)
Total articles ≅ 86,557
Latest articles in this journal
Journal of Physics: Conference Series, Volume 1275; doi:10.1088/1742-6596/1275/1/012024
Abstract:After a short introduction to the generalized uncertainty principle (GUP), we discuss heuristic derivations of the Casimir effect, first from the usual Heisenberg uncertainty principle (HUP), and then from GUP. Results are compared with those obtained from more standard calculations in Quantum Field Theory (QFT).
Journal of Physics: Conference Series, Volume 1275; doi:10.1088/1742-6596/1275/1/012035
Abstract:Quantum mechanics is a non local theory. To recover the locality principle some physicists suggested that the correlations between entangled particles could be established by communications propagating with a velocity vt > c in a preferred frame. In the previous DICE conference we reported the preliminary results of a high sensitivity experiment to test the superluminal models. Here we report the final results. No breaking of the quantum predictions has been found. Then, we infer that the velocity of the quantum communications has to be higher than a lower bound of the order of some millions of times the light velocity.
Journal of Physics: Conference Series, Volume 1275; doi:10.1088/1742-6596/1275/1/012021
Abstract:In the spirit of previous ideas in the neuroscience community, but with a more physics-oriented perspective, we propose that consciousness can be described as the collective excitation of a brainwide web of neurones. This picture is inspired by the fact that, in all major areas of physics, a collective excitation has just as much physical reality as a particle or other localized object. The brainwide web extends into those regions (neuronal networks) where processed information is received from the senses, memories, etc. (emerging out of unconscious processes in prior networks). It unifies those regions (plus motor control regions) via the vast complexity of the neuronal interactions that it spans. A crude analogy is the worldwide web, which extends into servers which have been prepared by external agents. Other crude analogies are the many collective excitations in physics. True understanding of consciousness must rely mostly on experiment, but since probes of living brains have limited precision, there is an important role for large-scale simulations in revealing details and complementing experiment. Petascale computational facilities should make it possible to perform simulations with realistic complexity.
Journal of Physics: Conference Series, Volume 1275; doi:10.1088/1742-6596/1275/1/012004
Abstract:After a short introduction to the generalized uncertainty principle (GUP), we review some of the physical predictions of the GUP, and we focus in particular on the bounds that present experimental tests can put on the value of the deformation parameter β. We also describe a theoretical value computed for β, and comment on the vast parameter region still unexplored, and to be probed by future experiments.
Journal of Physics: Conference Series, Volume 1275; doi:10.1088/1742-6596/1275/1/012049
Abstract:A concise review of the derivation of the Born rule and Schroedinger equation from first principles is provided. The starting point is a formalization of fundamental notions of measurement and composition, leading to a general framework for physical theories known as the positive formalism. Consecutively adding notions of spacetime, locality, absolute time and causality recovers the well established convex operational framework for classical and quantum theory. Requiring the partially ordered vector space of states to be an anti-lattice one obtains quantum theory in its standard formulation. This includes Born rule and Schroedinger equation.
Journal of Physics: Conference Series, Volume 1275; doi:10.1088/1742-6596/1275/1/012030
Abstract:External conditions have a dramatic impact on the way dynamical symmetry breaking occurs. In a curved background, the natural expectation is that curvature works toward the restoration of the internal symmetry. We show instead that, for topological defects, the competing action of the locally induced curvature and boundary conditions generated by the non-trivial topology allows configurations where symmetries can be spontaneously broken close to the core. Inspired by the effect of geometrical deformations on 2D lattices, we then propose a novel mechanism to induce a superconducting phase by triggering condensation along cosmic strings.
Journal of Physics: Conference Series, Volume 1275; doi:10.1088/1742-6596/1275/1/012022
Abstract:String theory has many compelling features, including higher dimensions, supersymmetry, and topological defects of central importance. Here we describe a theory which also contains these features, but which is much more ambitious than string theory and also much closer to experiment. Since the mathematical details are given in a much longer paper, we summarize only the most important results, which include SO(N) gauge unification, vanishing of the usual cosmological constant, and a credible dark matter candidate.
Journal of Physics: Conference Series, Volume 1275; doi:10.1088/1742-6596/1275/1/012044
Abstract:The theory of emerging quantum mechanics (EQM) is a quantum field theory in flat 11 dimensional spacetime, quantizing gravity in the weak interaction limit. In EQM the quantum fields materialize (i.e., they become real) if they entangle with the gravonons, i.e. localized gravitons, thereby forming beables. If not entangled with gravonons, the quantum field is in a limbo state as e.g. exemplified by the state inbetween source and screen in the double slit experiment. Quantum diffusion proceeds via repeated limbo - beable transitions. This leads to the impression that particles having been measured at a certain separation in space suddenly disappear and reappear at a different separation. For any cosmological experiment this is consistent with the interpretation that space has expanded. The rate of cosmic expansion is then equal to the rate of beable - limbo transitions. This rate is calculated from first principles and equals the experimentally determined Hubble parameter. Explicit calculations on the generation of the cosmic microwave radiation (CMB) require to consider the beabling process of the electromagnetic quantum field. The beabling condition is fulfilled for light-atom-lattices (LAL). Temperature emerges in EQM by escape of the particle out of the warp resonance (beable). Without fitting any free model parameter the CMB radiation temperature is 2.2 K, which is to be compared to the experimental value of 2.7 K.
Journal of Physics: Conference Series, Volume 1275; doi:10.1088/1742-6596/1275/1/012008
Abstract:The Leggett-Garg (LG) inequalities were introduced, as a temporal parallel of the Bell inequalities, to test macroscopic realism – the view that a macroscopic system evolving in time possesses definite properties which can be determined without disturbing the future or past state. The original LG inequalities are only a necessary condition for macrorealism, and are therefore not a decisive test. We argue, for the case of measurements of a single dichotomic variable Q, that when the original four three-time LG inequalities are augmented with a set of twelve two-time inequalities also of the LG form, Fine's theorem applies and these augmented conditions are then both necessary and sufficient. A comparison is carried out with the alternative necessary and sufficient conditions for macrorealism based on no-signaling in time conditions which ensure that all probabilities for Q at one and two times are independent of whether earlier or intermediate measurements are made. We argue that the two tests differ in their implementation of the key requirement of non-invasive measurability so are testing different notions of macrorealism, and these notions are elucidated.
Journal of Physics: Conference Series, Volume 1275; doi:10.1088/1742-6596/1275/1/012019
Abstract:Several tasks involving the determination of the time evolution of a system of solid state qubits require stochastic methods in order to identify the best sequence of gates and the time of interaction among the qubits. The major success of deep learning in several scientific disciplines has suggested its application to quantum information as well. Thanks to its capability to identify best strategy in those problems involving a competition between the short term and the long term rewards, reinforcement learning (RL) method has been successfully applied, for instance, to discover sequences of quantum gate operations minimizing the information loss. In order to extend the application of RL to the transfer of quantum information, we focus on Coherent Transport by Adiabatic Passage (CTAP) on a chain of three semiconductor quantum dots (QD). This task is usually performed by the so called counter-intuitive sequence of gate pulses. Such sequence is capable of coherently transfer an electronic population from the first to the last site of an odd chain of QDs, by leaving the central QD unpopulated. We apply a technique to find nearly optimal gate pulse sequence without explicitly give any prior knowledge of the underlying physical system to the RL agent. Using the advantage actor-critic algorithm, with a small neural net as function approximator, we trained a RL agent to choose the best action at every time step of the physical evolution to achieve the same results previously found only by ansatz solutions.