Foundations Of Quantum Physics Research Articles

Notes on Contributors

Notes on Contributors

Duality for the Logic of Quantum Actions

In this paper we show a duality between two approaches to represent quantum structures abstractly and to model the logic and dynamics therein. One approach puts forward a "quantum dynamic frame" (Baltag et al. in Int J Theor Phys, 44(12):2267---2282, 2005), a labelled transition system whose transition relations are intended to represent projections and unitaries on a (generalized) Hilbert space. The other approach considers a "Piron lattice" (Piron in Foundations of Quantum Physics, 1976), which characterizes the algebra of closed linear subspaces of a (generalized) Hilbert space. We define categories of these two sorts of structures and show a duality between them. This result establishes, on one direction of the duality, that quantum dynamic frames represent quantum structures correctly; on the other direction, it gives rise to a representation of dynamics on a Piron lattice.

Preface Special Issue Foundations of Physics

The foundations of quantum mechanics are attracting new and significant interest in the scientific community due to the recent striking experimental and technical progress in the fields of quantum computation, quantum teleportation and quantum information processing. However, at a more fundamental level the understanding andmanipulation of these novel phenomena require not only new laboratory techniques but also new understanding, development and interpretationof the formalismof quantummechanics itself, a mathematical structure whose connection to what happens in physical reality continues to present puzzles and engender debate. The present issue ofFoundations of Physics considers, from physical, philosophical and logical perspectives, a rangeof problems: these range from themeaningof quantum identity and individuality, through probability and complementarity, to decoherence and gauge theories. The idea of preparing this special issue was conceived in connection with the Workshop Logical Quantum Structures1, organized by Decio Krause and Christian de Ronde, which took place in Rio de Janeiro on 6 and 7 April 2013. The editors trust that the resulting compilation will give new impetus to a number of ongoing debates concerning the foundations of quantum physics.

Maxwell’s Equations as the Basis for Model of Atoms

A century ago the classical physics couldn’t explain many atomic physical phenomena. Now the situation has changed. It’s because within the framework of classical physics with the help of Maxwell’s equations we can derive Schrödinger’s equation, which is the foundation of quantum physics. The equations for energy, momentum, frequency and wavelength of the electromagnetic wave in the atom are derived using the model of atom by analogy with the transmission line. The action constant A0 = (μ0/ε0)1/2s02e2 is a key term in the above mentioned equations. Besides the other well-known constants, the only unknown constant in the last expression is a structural constant of the atom s0. We have found that the value of this constant is 8.277 56 and that it shows up as a link between macroscopic and atomic world. After calculating this constant we get the theory of atoms based on Maxwell’s and Lorentz equations only. This theory does not require knowledge of Planck’s constant h, which is replaced with theoretically derived action constant A0, while the replacement for the fine structure constant α-1 is theoretically derived expression 2s02 = 137.036. So, the structural constant s0 replaces both constants h and α. This paper also defines the stationary states of atoms and shows that the maximal atomic number is equal to Zmax = 137. The presented model of the atoms covers three of the four fundamental interactions, namely the electromagnetic, weak and strong interactions.

Solving large-scale optimization problems related to Bell’s Theorem

Impossibility of finding local realistic models for quantum correlations due to entanglement is an important fact in foundations of quantum physics, gaining now new applications in quantum information theory. We present an in-depth description of a method of testing the existence of such models, which involves two levels of optimization: a higher-level non-linear task and a lower-level linear programming (LP) task. The article compares the performances of the existing implementation of the method, where the LPs are solved with the simplex method, and our new implementation, where the LPs are solved with an innovative matrix-free interior point method. We describe in detail how the latter can be applied to our problem, discuss the basic scenario and possible improvements and how they impact on overall performance. Significant performance advantage of the matrix-free interior point method over the simplex method is confirmed by extensive computational results. The new method is able to solve substantially larger problems. Consequently, the noise resistance of the non-classicality of correlations of several types of quantum states, which has never been computed before, can now be efficiently determined. An extensive set of data in the form of tables and graphics is presented and discussed. The article is intended for all audiences, no quantum-mechanical background is necessary.

The Oxford Questions on the foundations of quantum physics

The twentieth century saw two fundamental revolutions in physics—relativity and quantum. Daily use of these theories can numb the sense of wonder at their immense empirical success. Does their instrumental effectiveness stand on the rock of secure concepts or the sand of unresolved fundamentals? Does measuring a quantum system probe, or even create, reality or merely change belief? Must relativity and quantum theory just coexist or might we find a new theory which unifies the two? To bring such questions into sharper focus, we convened a conference on Quantum Physics and the Nature of Reality. Some issues remain as controversial as ever, but some are being nudged by theory's secret weapon of experiment.

Foundations of Quantum Physics at the Beginning of XXIth Century

Foundations of Quantum Physics at the Beginning of XXIth Century

Physics at the FQMT'11 conference

This paper deals with the recent state of the art of the following topics presented at the FQMT'11 conference: foundations of quantum physics, quantum measurement; nonequilibrium quantum statistical physics; quantum thermodynamics; quantum measurement, entanglement and coherence; dissipation, dephasing, noise, and decoherence; quantum optics; macroscopic quantum behavior; e.g. cold atoms; Bose–Einstein condensates; physics of quantum computing and quantum information; mesoscopic, nano-electro-mechanical systems and nano-optical systems; spin systems and their dynamics; biological systems and molecular motors; and cosmology, gravitation and astrophysics. The lectures and discussions at the FQMT'11 conference, as well as the contributions to the related topical issue, reveal important themes for future development. The recent literature is included.

On the foundations of quantum physics

Some aspects of the interpretation of microscopic physics in terms of quantum theory are discussed. It is first emphasized that quantum theory is formulated in a Cartesian coordinate system; in other coordinates the result obtained with the help of the Hamiltonian formalism and commutation relations between ''canonically conjugated'' coordinate and momentum operators leads to a wrong version of quantum mechanics. In this connection the Feynman integral formalism is also discussed. In this formalism the measure is not well defined, and there is no idea how to distinguish between the true version of quantum mechanics and an incorrect one. In this respect, the Feynman approach consists of a mnemonic rule to generate perturbation series from an undefined zero-order term. The origin of time in the quantum framework is then analyzed in detail and illustrated by the example of atomic collisions. It is shown that the time-dependent Schr ¨ odinger equation for the closed three-body (two nuclei + electron) system has no physical meaning because in the high-impact energy limit it transforms into an equation with two independent time-like variables; time naturally appears in the stationary Schr ¨ odinger equation as a result of extraction of a classical subsystem (two nuclei) from a closed three-body system. Finally, following the well-known Einstein-Rosen-Podolsky experiment and Bell's inequality, we reiterate that the wave function must be interpreted as an actual field of information, in a form as elementary as the usual material particles and electromagnetic fields. In fact, experimental measurements transfer this quantum information field into the classical world, which is directly discernable. In my conclusion, the relation between physical reality and its mathematical formulation is discussed. 2012 Physics Essays Publication. (DOI: 10.4006/0836-1398-25.1.27) R ´

Productive conservatism: Planck's second theory of radiation

Since the first months of 1910, Max Planck began to think that his theory of radiation developed in 1900, albeit confirmed by all experimental measurements, was “plagued [. . . ] by a remarkable flaw”.1 After two years of intense work, changes of tack, doubts, and rethinking, Planck completed his second theory of radiation, which was published in a mature form on the pages of Annalen der Physik exactly one hundred years ago.2 In the introduction to the paper, Planck summarized the requirements that a satisfactory theory of radiation should fulfill: it must be (1) free of internal contradictions and (2) as close to the core of classical electrodynamics as allowed by the necessity of the quantum hypothesis. As Planck’s 1900 theory is mostly valid still today and it is at the very foundations of quantum physics, the modern reader cannot help being baffled by Planck’s effort. To understand why his celebrated first theory did not comply the requirements given above, we have to move a step backwards.

Fundamental Frontiers of Quantum Science and Technology

We discuss recent studies on the foundations of quantum physics with photonic, atomic, molecular and micromechanical systems as well as theoretical treatments of the interface between quantum physics and classical observations. Investigations of the type presented here elucidate important boundary conditions for quantum mechanics and help assessing their relevance for future quantum technologies.

Spectral Automorphisms in Quantum Logics

In quantum mechanics, the Hilbert space formalism might be physically justified in terms of some axioms based on the orthomodular lattice (OML) mathematical structure (Piron in Foundations of Quantum Physics, Benjamin, Reading, 1976). We intend to investigate the extent to which some fundamental physical facts can be described in the more general framework of OMLs, without the support of Hilbert space-specific tools. We consider the study of lattice automorphisms properties as a “substitute” for Hilbert space techniques in investigating the spectral properties of observables. This is why we introduce the notion of spectral automorphism of an OML. Properties of spectral automorphisms and of their spectra are studied. We prove that the presence of nontrivial spectral automorphisms allow us to distinguish between classical and nonclassical theories. We also prove, for finite dimensional OMLs, that for every spectral automorphism there is a basis of invariant atoms. This is an analogue of the spectral theorem for unitary operators having purely point spectrum.

Physics at the FMQT’08 conference

This paper summarizes the recent state of the art of the following topics presented at the FQMT’08 conference: Foundations of quantum physics, Quantum measurement; Quantum noise, decoherence and dephasing; Cold atoms and Bose–Einstein condensation; Physics of quantum computing and information; Nonequilibrium quantum statistical mechanics; Quantum, mesoscopic and partly classical thermodynamics; Mesoscopic, nano-electro-mechanical systems and optomechanical systems; Spins systems and their dynamics, Brownian motion and molecular motors; Physics of biological systems, and Relevant experiments from the nanoscale to the macroscale. To all these subjects an introduction is given and the recent literature is overviewed. The paper contains some 680 references in total.

On foundation of quantum physics

Some aspects of the interpretation of quantum theory are discussed. It is emphasized that quantum theory is formulated in the Cartesian coordinate system; in other coordinates the result obtained with the help of the Hamiltonian formalism and commutator relations between “canonically conjugated” coordinate and momentum operators leads to a wrong version of quantum mechanics. The origin of time is analyzed by the example of atomic collision theory in detail; it is shown that the time-dependent Schrödinger equation is meaningless since in the high-impact-energy limit it transforms into an equation with two time-like variables. Following the Einstein-Rozen-Podolsky experiment and Bell’s inequality, the wave function is interpreted as an actual field of information in the elementary form. The concept “measurement” is also discussed.

High-fidelity entanglement swapping with fully independent sources

Entanglement swapping allows one to establish entanglement between independent particles that never interacted or share any common past. This feature makes it an integral constituent of quantum repeaters. Here, we demonstrate entanglement swapping with time-synchronized independent sources with a fidelity that is high enough to violate a Clauser-Horne-Shimony-Holt inequality by more than four standard deviations. The fact that both entangled pairs are created by fully independent only electronically connected sources ensures that this technique is suitable for future long-distance quantum communication experiments as well as for novel tests on the foundations of quantum physics.

Foundations of quantum physics

Foundations of quantum physics

Quantum Information: Philosophical, Mathematical and Experimental Perspectives

The present issue of “Quantum Information Processing” (QIP) as well as the two subsequent issues will be a forum for a subset of distinguished speakers and authors who met at the University of Vienna in May 2005 to contribute to the international conference “Quantum Physics of Nature (QUPON2005)” and the 6th European workshop on “Quantum information processing and communication (QIPC)”. There is always a good reason for a top-level scientific meeting. But this time several additional motivations called for an event with outstanding scientists: The year 2005 was not only officially declared to be the UNESCO World Year of Physics, it was also the 100th anniversary of Albert Einstein’s paper on the quantum nature of light—, which marks the birthday of quantum optics. It also happened that the first day of the conference coincided with Anton Zeilinger’s 60th birthday, which is seen by many of us as an important date for Quantum Optics and QIP. While work on the foundations of quantum physics has long been regarded as a subject for philosophers rather than physicists, it has now transformed into an information science and correspondingly into an important field of research everywhere in the world: QIP is substantially and very successfully supported by the European Commission. The American physical society has started a new topical group to create a forum for QI. And the theme of “quantum information” (QI) has been the seed for a growing number of new research institutes in the US, Canada or Europe. Strong scientific and even already industrial consortia are also working in Asia and Australia towards quantum computing and quantum communication. And African groups are by now connected to the QI community, too. About 300 participants from 35 different countries and five continents attended QUPON2005 and QIPC2005 at the University of Vienna. 227

The Historical Roots of ‘‘Foundations of Quantum Physics’’ as a Field of Research (1950–1970)

The rising interest, in the late 20th century, in the foundations of quantum physics, a subject in which Franco Selleri has excelled, has suggested the fair question: how did it become so? The current answer says that experiments have allowed to bring into the laboratories some previous gedanken experiments, beginning with those about EPR and related to Bell’s inequalities. I want to explore an alternative view, by which there would have been, before Bell’s inequalities experimental tests, a change in the views shared by physicists concerning the intellectual status of that issue. I will take three cases which will serve as the threads of our story: the connections between Bohm’s causal interpretation and Bell’s inequalities; Wigner’s ideas on the measurement problem; and finally Everett’s relative states formulation. In the end, I will discuss how those threads were gathered together by creating foundations of quantum physics as a field of research.

Announcing a Symposium on “The Foundations of Quantum Physics before 1935” Berlin, 14–16 December 2000

Announcing a Symposium on “The Foundations of Quantum Physics before 1935” Berlin, 14–16 December 2000

Experiment and the foundations of quantum physics

Quantum physics, a child of the early 20th century, is probably the most successful description of nature ever invented by man. The range of phenomena it has been applied to is enormous. It covers phenomena from the elementary-particle level all me way to the physics of the early universe. Many modern technologies would be impossible without quantum physics—witness, for example, that all information technologies are based on a quantum understanding of solids, particularly of semiconductors, or that the operation of lasers is based on a quantum understanding of atomic and molecular phenomena.