Semantic incompleteness of quantum physics

We discuss the completeness of quantum physics (QP) from a nonrealistic viewpoint. To this end we make use of the formalized languageL for QP that we introduced in a recent paper and show that QP is incomplete both in an intuitive sense and in a more formal logical sense. We also show that a pure state is not physically equivalent to the physical property which characterizes it in QP, and that the set of all properties whose truth value can be predicted for a physical object in the stateS coincides with the set of all properties which are certainly true or certainly false inS. These results lead us to introduce a notion of compatibility between states which can be applied to the EPR experiment, in order to prove that no quantum paradox follows from it if our interpretation of states and physical properties is accepted.     

Erratum: Semantic incompleteness of quantum physics

This paper appeared inInternational Journal of Theoretical Physics,31(5), 809–824     

Semantic realism versus EPR-Like paradoxes: The Furry,Bohm-Aharonov,and Bell paradoxes

We prove that the general scheme for physical theories that we have called semantic realism(SR) in some previous papers copes successfully with a number of EPR-like paradoxes when applied to quantum physics (QP). In particular, we consider the old arguments by Furry and Bohm- Aharonov and show that they are not valid within a SR framework. Moreover, we consider the Bell-Kochen-Specker und the Bell theorems that should prove that QP is inherently contextual and nonlocal, respectively, and show that they can be invalidated in the SR approach. This removes the seeming contradiction between the basic assumptions of SR and QP, and proves that some problematic features that are usually attributed to QP, us contextuality and nonlocality, occur because of the adoption of a verificationist position, from one side, and from an insufficient adherence to the operational principles that have inspired QP itself, from the other side.     

The classic paradoxes of quantum theory

This paper contains four new dialogues among Simplicio, Salviati, and Sagredo, on the fate of Schrödinger's cat, the existence of physical quantities, the paradigm of Einstein, Podolsky, and Rosen, and why a watched kettle may boil, after all.Dedicated to Nathan Rosen, teacher and friend, on the occasion of his 75th birthday.     

Joint probabilities of noncommuting operators and incompleteness of quantum mechanics

We use joint probabilities to analyze the EPR argument in the Bohm's example of spins.⁽¹⁾ The properties of distribution functions for two, three, or more noncommuting spin components are explicitly studied and their limitations are pointed out. Within the statistical ensemble interpretation of quantum theory (where only statements about repeated events can be made), the incompleteness of quantum theory does not follow, as the consistent use of joint probabilities shows. This does not exclude a completion of quantum mechanics, going beyond it, by a more general theory of single events, using hidden variables, for example.     

量子力学佯谬及第二次量子革命

文章介绍了三个著名的量子力学佯谬,分别是有关量子力学与定域实在性、语境实在性,以及宏观实在性三者之间的关系。这三个佯谬对应三个思想实验,后来又发展出由隐变量理论和实在性推导出的不等式,这些不等式可以定量地判断量子力学和这些实在性之间的关系,使得纠缠等量子力学特性成为可以被真实探测和利用的资源,被广泛应用于量子保密通信、量子隐形传态、量子计算等任务中。量子信息理论的出现,进一步带动了量子通信、量子计算和量子传感等高新技术领域的产生和发展,开启了“第二次量子革命”     

Pre- and post-selection paradoxes and contextuality in quantum mechanics

Many seemingly paradoxical effects are known in the predictions for outcomes of intermediate measurements made on pre- and post-selected quantum systems. Despite appearances, these effects do not demonstrate the impossibility of a noncontextual hidden variable theory, since an explanation in terms of measurement disturbance is possible. Nonetheless, we show that for every paradoxical effect wherein all the pre- and post-selected probabilities are 0 or 1 and the pre- and post-selected states are nonorthogonal, there is an associated proof of the impossibility of a noncontextual hidden variable theory. This proof is obtained by considering all the measurements involved in the paradoxical effect--the preselection, the post-selection, and the alternative possible intermediate measurements--as alternative possible measurements at a single time.     

Classical physics and quantum loops

The standard picture of the loop expansion associates a factor of variant Planck's over 2pi with each loop, suggesting that the tree diagrams are to be associated with classical physics, while loop effects are quantum mechanical in nature. We discuss counterexamples wherein classical effects arise from loop diagrams and display the relationship between the classical terms and the long range effects of massless particles.     

Einstein's relativity and quantum physics

There are reasons to reject the idea that a field in empty space is a real physical entity. The nonexistence of the electromagnetic field and the gravitational field as physical entities leads to far-reaching consequences. The basic equations sufficient to constructclassical electrodynamics (the Maxwell equations and the Lorentz force equation) are obtained by combining quantum considerations with two premises: (a) there exists a subatomic particle, theemon, each concrete emon having a specific electric property described by aspacelike four-vector; (b) every concrete charged particle possesses a specific electric property described by atimelike four-vector. Some other points of interest are also discussed, in particular, ones related to Einstein's gravitational field as well as the action-at-a-distance versus local-action issue. Einstein's second postulate of special relativity is also shown to need some revision of principle.     

Local quantum physics and models

The problem of characterizing a specific model within the frame of local quantum physics is addressed.Dedicated to Huzihiro Araki     

Finite groups and quantum physics

Concepts of quantum theory are considered from the constructive “finite” point of view. The introduction of a continuum or other actual infinities in physics destroys constructiveness without any need for them in describing empirical observations. It is shown that quantum behavior is a natural consequence of symmetries of dynamical systems. The underlying reason is that it is impossible in principle to trace the identity of indistinguishable objects in their evolution—only information about invariant statements and values concerning such objects is available. General mathematical arguments indicate that any quantum dynamics is reducible to a sequence of permutations. Quantum phenomena, such as interference, arise in invariant subspaces of permutation representations of the symmetry group of a dynamical system. Observable quantities can be expressed in terms of permutation invariants. It is shown that nonconstructive number systems, such as complex numbers, are not needed for describing quantum phenomena. It is sufficient to employ cyclotomic numbers—a minimal extension of natural numbers that is appropriate for quantum mechanics. The use of finite groups in physics, which underlies the present approach, has an additional motivation. Numerous experiments and observations in the particle physics suggest the importance of finite groups of relatively small orders in some fundamental processes. The origin of these groups is unclear within the currently accepted theories—in particular, within the Standard Model.     

Inference in quantum physics

In quantum physics all experimental information is discrete and stochastic. But the values of physical quantities are considered to depict definite properties of the physical world. Thus physical quantities should be identified with mathematical variables which are derived from the experimental data, but which exhibit as little randomness as possible. We look for such variables in two examples by investigating how it is possible to arrive at a value of a physical quantity from intrinsically stochastic data. With the aid of standard probability calculus and elementary information theory, we are necessarily led to the quantum theoretical phases and state vectors as the first candidates for physical quantities.     

Novel quantum phases and mesoscopic physics in quantum gases

Among many notable jubilees brought by the year 2012, the one of a special importance for the community of statistical physicists was the 140th birth anniversary of Marian Smoluchowski (Maryan Ritter von Smolan Smoluchowski, 28.05.1872 - 5.09.1917), who was one of the pioneers of statistical physics and, on a larger scale, one of those who shaped modern physical science as a whole. The present issue of EPJ ST entitled From Brownian motion to self-avoiding walks and Lévy flights aims to reflect the evolution of Smoluchowski’s ideas in the field of statistics of interacting random and self-avoiding walks, stochastic equations for many-particle systems, physics of glass-forming and noise driven systems. Majority of papers in this issue were presented at the international conference in statistical physics that took place in Lviv (Ukraine) on July 3-6, 2012.     

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.     

量子物理学百年回顾

简述了量子物理学诞生的背景。它的诞生,打开了人们认识微观物质世界运动规律的大门。物质属性及其微观结构问题,只有在量子物理的基础上才在原则上得以解决．量子力学提供了所有现代科学的基础支柱。在过去一百年中,量子物理不仅对于说明众多自然现象取得了无与伦比的成功,它还引发了大量的技术应用。由于量子物理学的基本概念与人们日常生活经验如此不同,诞生伊始至今,对于量子力学原理的诠释存在持续不断的争论。量子理论以前所未有的深度改变了人们的世界观。     

The physics of quantum gravity

Quantum gravity is still very mysterious and far from being well understood. In this text we review the motivations for the quantification of gravity, and some expected physical consequences. We discuss the remarkable relations between scattering processes in quantum gravity and in Yang–Mills theory, and the role of string theory as a unifying theory.     

Preparation and measurement in quantum physics

To honor Henry Margenau on the occasion of his 90th birthday, we attempt in this essay to integrate certain aspects of the physics, philosophy, and pedagogy of quantum mechanics in a manner very much inspired by Margenau's idealist scientific epistemology. Over half a century ago, Margenau was perhaps the first philosopher of science to recognize and elaborate upon the essential distinction between thepreparation of a quantum state and themeasurement of an observable associated with a system in that state; yet in contemporary quantum texts that distinction rarely receives adequate emphasis even though, as we demonstrate, it may be explicated through a series of simple illustrations.     

新型超导量子比特及量子物理问题的研究

近年来,超导量子计算的研究有了很大的进展.本文首先介绍了nSQUID新型超导量子比特的制备和研究进展,包括器件的平面多层膜制备工艺和量子相干性的研究.这类器件在量子态的传输速度和二维势系统的基础物理问题研究方面有着很大的优越性.其次,国际上新近发展的平面形式的transmon和Xmon超导量子比特具有更长的量子相干时间,在器件的设计和耦合方面也有相当的灵活性.本文介绍了我们和浙江大学与中国科学技术大学等单位合作逐步完善的这种形式的Xmon器件的制备工艺、制备出的多种耦合量子比特芯片,以及参与合作,在国际上首次完成的多达10个超导量子比特的量子态纠缠、线性方程组量子算法的实现和多体局域态等固体物理问题的量子模拟.最后介绍了基于这些超导量子比特器件开展的大量的量子物理、非线性物理和量子光学方面的研究,包括在Autler-Townes劈裂、电磁诱导透明、受激拉曼绝热通道、循环跃迁和关联激光等方面形成的一整套系统和独特的研究成果.