Einstein,Podolsky, Rosen,and Shannon

The Einstein–Podolsky–Rosen paradox (1935) is reexamined in the light of Shannons information theory (1984). The EPR argument did not take into account that the observers information was localized, like any other physical object.Dedicated to the memory of James T. Cushing     

Einstein-Podolsky-Rosen entanglement in bad cavity case

This paper explores continuous variable entanglement in four-wave mixing when the atomic relaxation time is comparable to and longer than the cavity relaxation time.In this case the atomic memory is included in the field correlations and the entanglement in the output fields can be significantly enhanced.Einstein-Podolsky-Rosen (EPR) entanglement is achievable even in the bad cavity limit.This shows the EPR entanglement generation without need of good cavity.     

Quantum secure direct communication network with Einstein–Podolsky–Rosen pairs

We discuss the four requirements for a real point-to-point quantum secure direct communication (QSDC) first, and then present two efficient QSDC network schemes with an N ordered Einstein–Podolsky–Rosen pairs. Any one of the authorized users can communicate another one on the network securely and directly.     

Einstein—Podolsky—Rosen experiments: The structure of the probability space. II

In part I, we have described the Einstein-Podolsky-Rosen experiments in the framework of an axiomatic probability theory. In part II, we present the proofs of the results stated in part I.     

Erzwingt die Quantenmechanik eine drastische Änderung unseres Weltbilds? Gedanken und Experimente nach Einstein,Podolsky und Rosen

Do Quantum Mechanics Force us to Drastically Change our View of the World? Thoughts and Experiments after Einstein, Podolsky and Rosen Since the advent of quantum mechanics there have been attempts of its interpretation in terms of statistical theory concerning individual ‘classical’ systems. The very conditions necessary to consider hidden variable theories describing these individual systems as ‘classical’ had been pointed out by Einstein, Podolsky and Rosen in 1935: 1. Physical systems are in principle separable. 2. If it is possible to predict with certainty the value of a physical quantity without disturbing the system under consideration, then there exists an element of physical reality corresponding to this physical quantity. Together they are, as was shown by Bell in 1964, incompatible in principle with quantum mechanics and no more tenable in view of recent experiments. These experiments once more corroborate quantum theory. In order to understand their results we are forced either to drop the assumption of separability of physical systems (taken for self-evident in classical physics) or to change our concept of physical reality. After investigating the notion of separability and connecting the ‘EPR-correlations’ to the measurement problem we, conclude that a change of the concept of physical reality is indispensable. The revised concept should be compatible with both classical and quantum physics in order to allow a uniform view of the physical world.     

Einstein Supergravity and New Twistor String Theories

A family of new twistor string theories is constructed and shown to be free from world-sheet anomalies. The spectra in space-time are calculated and shown to give Einstein supergravities with second order field equations instead of the higher derivative conformal supergravities that arose from earlier twistor strings. The theories include one with the spectrum of N = 8 supergravity, another with the spectrum of N = 4 supergravity coupled to N = 4 super-Yang-Mills, and a family with N ≥ 0 supersymmetries with the spectra of self-dual supergravity coupled to self-dual super-Yang-Mills. The non-supersymmetric string with N = 0 gives self-dual gravity coupled to self-dual Yang-Mills and a scalar. A three-graviton amplitude is calculated for the N = 8 and N = 4 theories and shown to give a result consistent with the cubic interaction of Einstein supergravity.     

Local foliations and optimal regularity of Einstein spacetimes

We investigate the local regularity of pointed spacetimes, that is, time-oriented Lorentzian manifolds in which a point and a future-oriented, unit timelike vector (an observer) are selected. Our main result covers the class of Einstein vacuum spacetimes. Under curvature and injectivity bounds only, we establish the existence of a local coordinate chart defined in a ball with definite size in which the metric coefficients have optimal regularity. The proof is based on quantitative estimates for, on one hand, a constant mean curvature (CMC) foliation by spacelike hypersurfaces defined locally near the observer and, on the other hand, the metric in local coordinates that are spatially harmonic in each CMC slice. The results and techniques in this paper should be useful in the context of general relativity for investigating the long-time behavior of solutions to the Einstein equations.     

Accretion onto Charged Black Holes in Einstein and Massive Theories of Gravity *

The accretion process is being investigated onto some important black holes such as Born-Infeld-AdS black hole, non-linear charged black hole solution in AdS space-time and Einstein-Yang-Mills massive gravity in the presence of Born-Infeld nonlinear electrodynamics. We find out the relations of radial velocity, energy density and change of mass for mention black holes and analyze their behavior graphically for different values of equation of state parameters $\omega$. We also examine the relations for critical speed for these black holes. It is observed that for different state parameters different fluids exhibit different evolutions in black holes backgrounds. The energy density of some fluids is negative or positive near the black hole while other fluids become cause to increase or decrease in black hole mass.     

Local Hidden Variables Underpinning of Entanglement and Teleportation

Entangled states whose Wigner functions are non-negative may be viewed as being accounted for by local hidden variables (LHV). Recently, there were studies of Bell’s inequality violation (BIQV) for such states in conjunction with the well known theorem of Bell that precludes BIQV for theories that have LHV underpinning. We extend these studies to teleportation which is also based on entanglement. We investigate if, to what extent, and under what conditions may teleportation be accounted for via LHV theory. Our study allows us to expose the role of various quantum requirements. These are, e.g., the uncertainty relation among non-commuting operators, and the no-cloning theorem which forces the complete elimination of the teleported state at its initial port.     

Local existence of symmetric spinor potentials for symmetric (3,1)-spinors in Einstein space–times

We investigate the possibility of existence of a symmetric potential H_ABA′B′=H_{(AB)(A′B′)} for a symmetric (3,1)-spinor L_ABCA′, e.g., a Lanczos potential of the Weyl spinor, as defined by the equation L_ABCA′=_(A^B′H_BC)A′B′. We prove that in all Einstein space–times such a symmetric potential H_ABA′B′ exists. Potentials of this type have been found earlier in investigations of some very special spinors in restricted classes of space–times. A tensor version of this result is also given. We apply similar ideas and results by Illge to Maxwell’s equations in a curved space–time.     

Local and Global Light Bending in Einstein's and Other Gravitational Theories

To remedy a certain confusion in the literature, we stress the distinction between local and global light bending. Local bending is a purely kinematic effect between mutually accelerating reference frames tracking the same signal, and applies via Einstein's equivalence principle exactly and equally in Newton's, Einstein's, Nordström's and other gravitational theories, independently of all field equations. Global bending, on the other hand, arises as an integral of local bending and depends critically on the conformal spacetime structure and thus on the specific field equations of a given theory.     

The contact — impedance meter — 2

In part 1 the general principles of the contact-impedance method of hardness testing were discussed. In this second part the equation governing the resonance of the testing system is set up and analyzed, and an experimental verification of the predicted results is described.     

Local Operator Products and Field Equations in P(φ)2 Theories

In P(φ)₂ theories with small coupling constants, local fields exist which are obtained from normal ordering of Euclidean fields. Normal ordering with respect to the free measure and the physical measure leads to the same family of fields. The coefficients of the two resulting field equations are related by a fixed point problem. Conditions are exhibited under which there is a unique solution.     

The spin evolution of spin-3 52Cr Bose–Einstein condensate

This paper studies theoretically the spin evolution of a Bose--Einstein condensate starting from a mixture of two or three groups of ⁵²Cr (spin-3) atoms in an optical trap. The initial state is so chosen that the condensate has total magnetization zero so that the system does not distinguish up and down. It is assumed that the system is very dilute (particle number is very small), the temperature is very low, and the frequency of the harmonic trap is large enough. In these situations, the deviation caused by the neglect of the dipole--dipole interaction and by using the single-mode approximation is reduced. A theoretical calculation beyond the mean field theory is performed and the numerical results are helpful for the evaluation of the unknown strength g0.     

An Analytical Treatment of the Clock Paradox in the Framework of the Special and General Theories of Relativity

No Heading In this paper we treat the so called clock paradox in an analytical way by assuming that a constant and uniform force F of finite magnitude acts continuously on the moving clock along the direction of its motion assumed to be rectilinear (in space). No inertial motion steps are considered. The rest clock is denoted as (1), the to and fro moving clock is (2), the inertial frame in which (1) is at rest in its origin and (2) is seen moving is I and, finally, the accelerated frame in which (2) is at rest in its origin and (1) moves forward and backward is A. We deal with the following questions: (1) What is the effect of the finite force acting on (2) on the proper time interval ⁽²⁾ measured by the two clocks when they reunite? Does a differential aging between the two clocks occur, as it happens when inertial motion and infinite values of the accelerating force is considered? The special theory of relativity is used in order to describe the hyperbolic (in spacetime) motion of (2) in the frame I. (II) Is this effect an absolute one, i.e., does the accelerated observer A comoving with (2) obtain the same results as that obtained by the observer in I, both qualitatively and quantitatively, as it is expected? We use the general theory of relativity in order to answer this question. It turns out that _I = _A for both the clocks, ⁽²⁾ does depend on g = F/m, and = ⁽²⁾/⁽¹⁾ = (1 – ²atanhj)/ < 1. In it ; = V/c and V is the velocity acquired by (2) when the force is inverted.