Bell’s Theorem without Inequalities and without Unspeakable Information

A proof of Bell’s theorem without inequalities is presented in which distant local setups do not need to be aligned, since the required perfect correlations are achieved for any local rotation of the local setups.     

Model of Raman–Nath acousto-optic diffraction

In this Letter, we discuss Raman–Nath acousto-optic diffraction, and a new model of Raman–Nath acousto-optic diffraction is presented. The model is based on the individual and simultaneous occurrences of phase-grating diffraction and the Doppler effect and optical phase modulation and photon–phonon scattering. We find that the optical phase modulation can cause temporal and spatial fluctuations of the diffracted light power escaping from the acoustic field.     

Minimal renormalization without ε-expansion

The minimal subtraction scheme and the Borel resummation method are used to calculate the amplitudes of renormalized correlation functions belowT _c for the three-dimensional ⁴ model with a oneccomponent order parameter. Accurate representations are given for the effective amplitudes of the renormalized expressions of the order parameter, of the susceptibility and of the specific heat. The resummed higher-order contributions to the order parameter,and to the specific heat turn out to yield only small corrections to the low-order approximations. Our results provide the basis for accurate analyses of the critical behavior of Ising-type systems in three dimensions belowT _c including the amplitude functions.     

Coherent X-ray diffraction investigation of twinned microcrystals

Coherent X-ray diffraction has been used to study pseudo-merohedrally twinned manganite microcrystals. The analyzed compositions were Pr(5/8)Ca(3/8)MnO(3) and La(0.275)Pr(0.35)Ca(3/8)MnO(3). The prepared loose powder was thermally attached to glass (and quartz) capillary walls by gentle heating to ensure positional stability during data collection. Many diffraction data sets were recorded and some of them were split as expected from the main observed twin law: 180° rotation around [101]. The peak splitting was measured with very high precision owing to the high-resolution nature of the diffraction data, with a resolution (Δd/d) better than 2.0 × 10(-4). Furthermore, when these microcrystals are illuminated coherently, the different crystallographic phases of the structure factors induce interference in the form of a speckle pattern. The three-dimensional speckled Bragg peak intensity distribution has been measured providing information about the twin domains within the microcrystals. Research is ongoing to invert the measured patterns. Successful phase retrieval will allow mapping out the twin domains and twin boundaries which play a key role in the physical properties.     

Time without clocks—An attempt

We try to define time intervals separating two states of systems of elementary particles and observers. The definition is founded on the notion of instant state of the system and uses no information connected with the use of a clock. Applying then the definition to a classical clock and to a sample of unstable particles, we obtain results in agreement with experiment. However, if the system contains few elementary particles, the properties of the time interval present some different features.     

Mössbauer effect diffraction from polycrystalline57Fe

We built a Debye-Scherrer type powder diffractometer with a⁵⁷Co radiation source and a large-angle position-sensitive detector. We tuned the incident -ray beam on and off the Mössbauer effect resonance, and measured diffraction patterns from our textured samples of polycrystalline⁵⁷Fe. Mössbauer effect diffraction dominated over X-ray diffraction for the higher order Bragg peaks.     

Drell–Yan diffraction: breakdown of QCD factorization

We consider the diffractive Drell–Yan process in proton–(anti)proton collisions at high energies in the color dipole approach. The calculations are performed at forward rapidities of the leptonic pair. The effect of eikonalization of the universal “bare” dipole–target elastic amplitude in the saturation regime takes into account the principal part of the gap survival probability. We present predictions for the total and differential cross sections of the single-diffractive lepton-pair production at RHIC and LHC energies. We analyze implications of the QCD factorization breakdown in the diffractive Drell–Yan process, which is caused by a specific interplay of the soft and hard interactions, resulting in rather unusual properties of the corresponding observables.     

PT-symmetric electronic dimer without gain material

In this paper, a way of building an electronic Parity Time(PT)-symmetric dimer without gain material is presented. This is achieved by capacitively coupling a pair of LZC circuits, each combining an inductance L, an imaginary resistance Z and a positive/negative capacitance C. We derive the effective Hamiltonian of the system, which commutes with the joint PT operator. The eigenspectrum displays spontaneous breaking points, where the system undergoes a transition from real to complex values. The...     

Picosecond photorefractive diffraction in CdTe at 1 μm

Using a ps-transient grating technique the contribution of the ps-photorefractive effect to the first-order probe-beam diffraction signal has been studied in CdTe at 1 m investigating diffraction kinetics at different sample orientations in the thin grating regime. A fast photorefractive grating formation time during the pump pulses and a characteristic decay time of 600 ps, shorter than the free-carrier lifetime, have been observed.     

Babinet’s principle in scalar theory of diffraction

In this work, we present an original proof of Babinet’s principle within the framework of the scalar theory of diffraction. The proof is derived in the case of the Fraunhofer diffraction, directly from the Fresnel-Kirchhoff formula, using properties of Fourier analysis and integral calculus, without considering Babinet’s principle itself for scalar waves. From the same proof, we also mathematically verify that, in the case of Fresnel diffraction, Babinet’s principle is fulfilled but in its more general scalar version.     

Laser beam characteristic for laser resonators with diffraction optical elements

The matrix eigenvalue method is used to analyze a laser resonator composed of diffraction optical elements. The results show that this type of resonator can separate fundamental mode and high order modes effectively. The output beams can be designed for different requests.     

Remote Three-Atom Information Concentration without Bell-State Measurement

We propose a scheme for information concentration of three remote two-level atoms in cavity QED. Our scheme does not involve the Bell-state measurement. During the interaction between atom and cavity, the cavity frequency is largely detuned from the atomic transition frequency, thus the scheme is insensitive to both the cavity decay and the thermal field. The idea can also be used to realize the remote information concentration of trapped ions.     

Threshold quantum secure direct communication without entanglement

For the first time, a threshold quantum secure direct communication (TQSDC) scheme is presented. Similar to the classical Shamir's secret sharing scheme, the sender makes n shares, S1, …, Sn of secret key K and each receiver keeps a share secretly. If the sender wants to send a secret message M to the receivers, he en-codes the information of K and M on a single photon sequence and sends it to one of the receivers. According to the secret shares, the t receivers sequentially per-form the corresponding unitary operations on the single photon sequence and ob-tain the secret message M. The shared shares may be reusable if it can be judged that there is no eavesdropper in line. We discuss that our protocol is feasible with current technology.     

Accurate measurement of ultrasonic velocity by eliminating the diffraction effect

The accurate measurement method of ultrasonic velocity by the pulse interference method with eliminating the diffraction effect has been investigated in VHF range experimen-tally. Two silicate glasses were taken as the specimens, their frequency dependences of longitu-dinal velocities were measured in the frequency range 50-350 MHz, and the phase advances of ultrasonic signals caused by diffraction effect were calculated using A. O. Williams‘ theoreticalexpression. For the frequency dependences of longitudinal velocities, the measurement resultswere in good agreement with the simulation ones in which the phase advances were included.It has been shown that the velocity error due to diffraction effect can be corrected very well bythis method.     

On Gleason’s Theorem without Gleason

The original proof of Gleason’s Theorem is very complicated and therefore, any result that can be derived also without the use of Gleason’s Theorem is welcome both in mathematics and mathematical physics. In this paper we reprove some known results that had originally been proved by the use of Gleason’s Theorem, e.g. that on the quantum logic ℒ(H) of all closed subspaces of a Hilbert space H, dim H≥3, there is no finitely additive state whose range is countably infinite. In particular, if dim H=n, then on ℒ(H) there is a unique discrete state, namely m(A)=dim A/dim H, A∈ℒ(H). Dedicated to Pekka J. Lahti on the occasion of his 60th birthday. The paper has been supported by the Center of Excellence SAS–Physics of Information–I/2/2005, the grant VEGA No. 2/6088/26 SAV, by Science and Technology Assistance Agency under the contract APVV-0071-06, Bratislava, Slovakia.     

评介“High energy electron diffraction and microscopy”一书

这是一部由现在在国内工作的中国科学家作为第一作者,由国际一流出版社以高级系列丛书形式出版的学术专著.合作者之一Whelan教授是薄膜透射电子显微学的创始人之一.著名电子显微学家、美国的JohnSpence教授对该书给予了高度评价 [1]:赞扬这是一本极好的书 (“asuperbbook”), “是所有从事电子显微学工作的实验室都必须有的书”.该书第一作者彭练矛教授 (北京大学首批长江特聘教授之一 )在 20世纪八、九十年代在美、英先后师从国际上著名的电子显微学权威J. M. Cowle和M. Whelan教授,有深厚的理论基础和娴熟的实验技巧.他在 1994年…     

Design of a MeV ultra-fast electron diffraction experiment at Tsinghua university

Time-resolved MeV ultra-fast electron diffraction (UED) is a powerful tool for structure dynamics studies. In this paper, we present a design of a MeV UED facility based on a photocathode RF gun at Tsinghua University. Electron beam qualities are optimized with numerical simulations, indicating that resolutions of 250 fs and 0.01 AA, and bunch charge exceeding 10⁵ electrons are expected with technically achievable machine parameters. Status of experiment preparation is also presented.     

X-ray diffraction from solids under nonhydrostatic compression—some recent studies

Diamond anvil cells have been extensively used to generate pressures up to a few hundred gigapascals. A fine X-ray beam from a synchrotron source permits recording of diffraction patterns from the pressurized samples. Such high pressures (stresses) however are not hydrostatic. Modeling of the stress state and resulting lattice strains in the sample give information on the compression behavior of solids. It is possible to derive the hydrostatic equation of state, shear strength and single-crystal elastic moduli by suitably interpreting the line shift data from powder diffraction patterns taken under nonhydrostatic compression. Nonhydrostatic compression leads to the broadening of diffraction lines. The analysis of temperature dependence of line-widths gives information on rheology of solids. The developments in the field are reviewed. The origins of line-shift and line-width are discussed using a generalized approach.     

Right handed or left handed? Forbidden x-ray diffraction reveals chirality

Enantiomers, or stereoisomers, have crystal structures that are mirror images of each other and are thus handed, like our right and left hands. The physical properties of enantiomers are identical except for optical activity, which rotates linearly polarized light by equal amounts but in opposite directions. While conventional x-ray Bragg diffraction can determine crystal structures, it does not distinguish between right- and left-handed crystals. We show resonant Bragg diffraction using circularly polarized x rays reveals the handedness of crystals by coupling x-ray helicity to a crystal screw axis. The intensity of resonantly allowed reflection of alpha-quartz is well described by an admixture of a parity-even and a parity-odd process. Our results are of general importance and demonstrate a new method to directly study chiral motifs in structures that include biomaterials, liquid crystals, magnets, multiferroics, etc.